Ti-doped MOO x coating on a particulate substrate

Abstract

The present invention relates to a method for producing a conductive, Ti-doped MoOx coating, with 2 ≤ x ≤ 3, a Ti:Mo ratio from 1 to 99 mol%, on a particulate substrate by gas phase deposition, comprising the steps: a. Providing the particulate substrate; b. contacting it with vaporised Ti and Mo precursors, thereby forming precursor material layer; c. contacting the precursor layer with a vaporized oxidant and react with the precursor layer at a temperature T1 allowing for removal of ligands from the precursor(s), yielding a Ti-doped MoOx layer on the substrate surface; d. carrying out steps b. - c. for multiple cycles to stack layers of the coating until a coating thickness d1 between 0.1 and 50 nm is obtained; and e. annealing the coating at elevated temperatures T2.

Description

[0001] Ti-doped MoOxCoating on a Particulate Substrate

[0002] Technical Field

[0003] The present invention relates to a method for producing a conductive, Ti-doped MoOxcoating, wherein 2 < x < 3, on a particulate substrate by gas-phase deposition, on a particulate substrates comprising a conductive layer of a Ti-doped MoOxcoating, wherein 2 < x < 3, of a thickness di comprised between 0.1 and 50 nm obtainable by the process according to the present invention, as well on uses of particulate substrates according to the present invention.

[0004] Background and Prior Art

[0005] Modern electrochemical cells comprise conductive material in electrodes or attached to membranes (such as in fuel cells).

[0006] The conditions prevailing in the various electrochemical cells can have a negative impact on the longevity of the active materials material used therein.

[0007] This holds particularly true for electrochemical cells as used in electrolysis, which is a very important application.

[0008] Electrolysis is essential for clean hydrogen production, and there is an ongoing need of new materials useful for electrolysis applications, in particular for use in electrolysis of water, yielding, among other, hydrogen.

[0009] The demand for hydrogen is huge and expected to increase considerably, and so is the demand for clean hydrogen, available by electrolysis powered by renewable energy. Bearing in mind that in 2020, the global hydrogen production was about 90 Mt, and that by 2050, the demand is expected to reach 250 Mt, whereas only 3.6% of the hydrogen currently produced stem from electrolysis that could utilize renewable energy sources, it becomes clear that significant upscaling of the electrolyzing industry is required to meet the need for clean hydrogen, i.e. hydrogen obtained via electrolysis powered by renewable energy.

[0010] Electrolysis of water using a proton exchange membrane (PEM) - also referred to as “proton exchange membrane water electrolysis” (PEMWE) is an attractive technology owing to the high efficiency, low operating temperature and lack of minimum voltage requirements of proton exchange membranes, which properties make PEM particularly suitable and attractive for small-scale applications and variable electrical inputs.

[0011] PEMs have a high investment cost and moderate lifetimes. The rate determining step in PEM cells is the oxygen evolution on the anode. A typical catalyst used is Iridium black, consisting of pure Ir nanoparticles. Using this type of catalyst would require about 500 kg of Ir per 1 GW of capacity. The Ir produced on an annual basis amounts to 7000-9000 kg. This illustrates that the use of Ir blackfor PEM electrolysis is neither sustainable nor economic, in particular when considering large scale operations and wide-spread commercialization as would be required to meet the demand for uses such as clean hydrogen production using PEM.

[0012] A strategy for reducing the cost of PEMs is to reduce the amount of Ir catalyst used on the anode. In the past, a reduction of from 1 -2 mg / cm2to 0.07 mg / cm2has been achieved by coating a support material with an Ir catalyst. Since only the surface of the Ir is catalytically active, the same or better performance can be achieved with coated core-shell particles as compared with Ir black. This is e.g. described in Dutch Patent Application No. NL2036587, incorporated herein by reference.

[0013] A technique that has been investigated in this context is atomic layer deposition (ALD). ALD allows for precise control of the deposition rate while forming strong covalent bonds between the surface and the deposited material, increasing durability. Yet ALD can only deposit low layer thicknesses (<50 nm) of Ir in the form of clusters. Ir containing clusters are in addition less stable than Ir containing films. Depositing 1 -2 nm layers of Ir or lrOxon the surface stabilizes the catalyst while boosting the catalytic surface available for oxygen evolution, hence increasing the lifetime and performance of a corresponding electrolyser cell. An ALD technique capable of producing <2nm thick I rOxcoatings on support particles has been developed lately. This is e.g. described in Dutch Patent Application No. NL2036587, incorporated herein by reference.

[0014] Yet this technique still requires that the support material be shielded effectively from the surrounding for it to remain stable in the harsh conditions that prevail in electrochemical cells, in particular in electrolyzers. I.e. such a coating requires coating material in an amount which is sufficient to achieve a complete coating, surrounding substrate particles essentially entirely. Thus, even though modern developments, when compared to using Iridium black, help to save precious resources such as Ir, it still requires precious resources in an amount exceeding the amount need if it were only to achieve a useful catalytic activity.

[0015] This does not only hold true for IrOx-catalysts, but also for many other catalysts materials used in electrochemical cells, including active materials used in batteries and fuel cells.

[0016] A major issue with I rOxor other catalysts remains their stability in the electrochemical cells such as used in an electrolyzer. One of the degradation mechanisms is driven by catalyst support surface degradation. Only a handful of materials are known to survive the harsh acidic conditions of PEMWE under applied voltage. These materials are typically metal oxides, such as I rO2, TiO2, ZrO2, WO3, etc., with the notable exception of Pt. Platinum Group Metals (PGMs) need to be replaced due to their scarcity, as well as for economic reasons. Instead, less precious metal oxides should be used. However, all stable metal oxides which hitherto known for PEMWE applications are electrical insulators. As such, the Ohmic resistance becomes too high in operation which in turn results in loss of efficiency. TiOx may be an interesting exception with high durability and conductivity in very specific oxygen-deficient stoichiometry(ies). Yet, there is strong evidence that TiO2 / TiOxdegrades the proton conductive ionomer in close contact, making the use of this material questionable in industrial settings. Doped metal oxides, metal nitrides, and metal borides were investigated in great detail in combination with the I rOxcatalyst. These materials, while more conductive, fell short of the stringent durability requirements. Providing a continuous coating of a catalytic material which is conductive is a viable solution, which, however, requires more of the catalytic material than would otherwise be required. Conductive materials comprising Molybdenum oxide, or, more generally, transition metal oxides and their potential use in electrochemical cells of all kinds have been investigated for quite some time now.

[0017] US20020028382A1 describes a Mn-doped MoOa material sputter-deposited on an Al containing substrate as an electrode material in the form of a 2 pm thickthin film.

[0018] CN105161700B describes flame spray combustion method to prepare a molybdenum trioxide coated molybdenum doped titanium dioxide nano composite particle material. The reaction is described as a “rapid high-temperature gas phase reaction”, which combines a doping of Mo ions into TiO2with growth of surface MoO3, wherein the Mo ion doping is described to improve the electrical conductivity of TiO2, and the surface growth of MOO3is described to provide additional lithium intercalation space, increase specific capacity, ensure high electrochemical activity and high rate performance of the material. That material is applied to an anode material of a lithium ion battery. The Mo-dopant is said to ameliorate conductivity of the TiO2, yet the material comprises different crystalline phases, i.e. rutile and anatase, and comprises the low conductivity phase of MoO3rather than the conductive MoO2phase

[0019] US20180183054A1 describes a transition metal-doped MoO3material for use in electrodes. The dopant is only present in amounts of between 0.15 and 1 mole %. The material is described as a powder, i.e. it is prepared in particular form.

[0020] EP3647456A1 relates to a cathode active material using a molybdenum oxide coating obtainable by PVD, ALD, CVD. No dopants of the molybdenum oxides are described, and a preferred oxidation state of the molybdenum is not mentioned.

[0021] US20130095251 A1 mentions a plate material comprising a metal oxide layer on a conductive layer to make to make the plate conductive, hydrophilic and stable in a fuel cell environment, the plate material being selected from a group including TiOxthat may be doped with a dopant chosen from a list of dopants including Mo. CN118407022A and CN117089821 A relate to methods for preparing MoO3films based on atomic layer deposition on a silicon substrate.

[0022] WO2010114386A1 discloses MoO3thin films prepared by atomic layer deposition (ALD), using precursors such as M0CI5, Mo(CO)6, Mo(thd)2(thd = 2,2,6,6-tetramethylheptane-3,5- dione), cycloheptatriene molybdenum tricarbonyl, pentamethyl- cyclopentadienylmolybdenum dicarbonyl dimer and derivates.

[0023] US20220220607A1 describes Mo° metal coordination complexes comprising a cycloheptatriene ligand and optionally one or more neutral ligands respectively coordinated by carbon, nitrogen or phosphorous and their use as precursors for the deposition of Mo comprising thin films on substrates as used in the field of semiconductors.

[0024] US20160002786A1 discloses Bis(alkylimido)-bis(alkylamido)molybdenum compounds as precursors for the deposition of Mo-containing films in the field of semiconductors.

[0025] US10731251 B2 and W02016024407A1 disclose group 6 transition metal-containing precursors forfilm forming compositions for use in the field of semiconductors, including Mo(=O)2(NR2)2, MO(=NR)2(OR)2, wherein R is H, a Ci.6alkyl group or SiR’3, wherein R’ is H or a C1-6 alkyl group, such as e.g. Mo(=NtBu2)2(OiPr)2, Mo(=NtBu2)2(OtBu)2, Mo(=NtBu2)2(OEt)2, Mo(=NtBu2)2(N(SiMe3)2)2.

[0026] US20170268107 and US11021793B2 describe a huge variety of group 6 transition metalcontaining precursors for use in the preparation of thin films in the field of semiconductors.

[0027] WO2024182651 A1 discloses a range of Molybdenum imido alkyl / allyl complexes functioning as precursors for the deposition of thin films in the field of electronics, such as e.g. Mo(NtBu)2(CH2SiMe3)2, Mo(NtBu)2Me2, Mo(NtBu)2(allyl)2. Ti precursors for ALD and CVD applications such as e.g. Ti(MeCp)(OMe)3, Ti(Me5Cp)(OMe)3, Ti(Cp(NMe3)2, TiMe5Cp(NMe2)3are known from ECS Transactions, 25(4), 217-230 (2009).

[0028] Maksumova, A. M., Abdulagatov, I. M., Palchaev, D. K., Rabadanov, M. Kh., Abdulagatov, A., I., “Studyingthe Atomic Layer Deposition of Molybdenum Oxide and Titanium- Molybdenum Oxide Films Using Quartz Crystal Microbalance”, Russian Journal of Physical Chemistry A, 2022, 96 (10), 226-2214, doi: 10.1134 / S0036024422100181 describes the growth of MoOxand TixMoyOzthin films using TiCU, MoOCL, and water as reactants. The deposition was carried out using TiCL4 / H2O and MoOCU / HjO supercycles to incorporate both elements.

[0029] CN111864075A describes the use of a MoO3 / TiO2buffer layer for perovskite solar cells deposited by ALD.

[0030] US20120171839A1 relates to atomic layer deposition of TiO2doped with Al, Sc, Sr, or Y, where the TiO2layer is less than 1 nm thick. US20040018307 relates to co-dosing of Ta- and Ti-based reactants to form TaTiOxthin films using an ALD-based process. The mixed oxide thin film is applied to flat semiconducting substrates such as Si and meant for use as a dielectric layer.

[0031] As regards the possibilities to enhance properties of electrodes in batteries, it is known from "Quantifying the effect of electrical conductivity on the rate-performance of nanocomposite battery electrodes" by Ruiyuan Tian et al. (2019) that electrode conductivity can influence rate performance in Lithium-Nickel-Manganese-Cobalt-Oxide (NMC) cathodes. The researchers found that increasing the out-of-plane conductivity of the electrode enhances rate performance by decreasingthe RC charging time. They suggest that incorporating less than 1 wt% single-walled carbon nanotubes can achieve the desired conductivity improvement. Yet carbon nanotubes are only moderately stable in corresponding environments. There is accordingly a need for corresponding improved materials.

[0032] Similar considerations have been made with regard to PEM Fuel cells, i.e. "Electronic conductivity of catalyst layers of polymer electrolyte membrane fuel cells: Through-plane vs. in-plane" by Mohammad Ahadi et al. (2019) developed novel procedures to measure both in-plane and through-plane electronic conductivities of catalyst layers (CLs) in polymer electrolyte membrane fuel cells (PEMFCs). The researchers found that CLs exhibit anisotropic electronic conductivity, with through-plane values being three orders of magnitude lower than in-plane values. This anisotropy significantly impacts fuel cell performance, emphasizingthe importance of optimizing electronic pathways within the CLs. There is accordingly a need for improved catalyst materials.

[0033] "Composite Anode for PEM Water Electrolyzers: Lowering Iridium Loadings with Conductive Supports" by K. Ferner et al. (2024) investigates the use of conductive support particles to reduce iridium loadings in PEM water electrolyzer anodes. The research shows how the activity can be improved several times by adding a conductive platinum additive. Yet Pt is comparably expensive. Again, there is accordingly a need for improved catalyst materials.

[0034] Im, K., Yoo, S.J., Yoo, K.S. et al. Facile Spray Pyrolysis Synthesis of Various Metal-Doped MoO2Microspheres for Catalytic Partial Oxidation of n-Dodecane. Catal Lett 148, 2510- 2515 (2018). https: / / doi.org / 10.1007 / s10562-018-2423-3 describe known materials most usually comprise Mo in higher oxidation states (V & VI), which is more stable than Mo (IV). The unique benefit of Mo(IV), referred to as MoO2is its high electrical conductivity comparable to pure metals. To stabilize the lower oxidation state under the harsh conditions of the PEM electrolyser, dopants are necessary, such as Ti, Zr, or Co. These species act as reducing agents to form the MoO2phase, which is a result of the different electronegativity between the dopant and Mo atoms located in the structure. Additionally, roughening of the resulting nanostructure was correlated with increasing M4+ion size compared to Mo(IV).

[0035] While using Ti as a dopant has been described to enhance the stability of corresponding materials, higher Ti contents in MoO2so far have not been attempted and / or achieved, e.g. because of phase separation, or for other reasons. Eom-Ji Kim, JaewookShin, Junu Bak, Sang Jae Lee, Ki hyun Kim, DongHoon Song, JeongHan Roh, Yongju Lee, HyoWon Kim, Kug-Seung Lee, EunAe Cho, “Stabilizing role of Mo in TiO2-MoOxsupported Ir catalyst toward oxygen evolution reaction”, Applied Catalysis B: Environmental, Volume 280, 2021 , 119433, ISSN 0926- 3373, https: / / doi.Org / 10.1016 / j.apcatb.2020.119433 describe various TiO2and MoOxcomposites prepared according to a hydrothermal method and used as a support for an Ir nanoparticle catalyst, applied from solution. In this case, the Ti-doped MoOxwas not applied as a coating on another support materials but as the support material itself. According to the authors, theirTi-doped MoOxmaterial had a particles size of 10 nm and below. At least some of the composites had separate phases (amorphous and various crystalline phases). The authors showed that they could only achieve about 10 at% doping of Ti in MoOx, with higher fractions of Ti leading to phase separation in TiO2anatase crystals. Irrespective thereof, the structure, form, composition, size and size distribution of the carrier composites can only be controlled to a limited extent.

[0036] There is in other words a need for new conductive materials and processes which comprise Mo in a lower oxidation state, i.e. Molvrather than Movl, which preferably are essentially stable in harsh environment as encountered in a redox electrolysis cell. Ideally, these materials should be readily available and suited as a support for catalysts as used in PEMs as used in electrochemical cells of electrolyzers, e.g. Ir catalysts, and / or suited as a conductive material for use in electrochemical cells such as e.g. in cathodes, and anodes of lithium-ion or sodium-ion battery cells.

[0037] Summary of the invention

[0038] According to the first aspect of the present invention, the abovementioned need is met by a method for producing a conductive, Ti-doped MoOxcoating, wherein 2 < x < 3 and wherein the Ti:Mo ratio in mol% is between 1 % to 99%, 1 % to 66% or 1 % to 33%, on a particulate substrate by gas-phase deposition. According to a second aspect, the need is further met by particulate substrates obtainable by a method according to the first aspect of the present invention. Further aspects of the present invention concern the various uses of corresponding particulate substrates. The method according to the first aspect of the present invention is a method for producing a conductive, Ti-doped MoOxcoating, wherein 2 < x < 3 and wherein the Ti:Mo ratio in mol% is between 1% to 99%, 1% to 66% or 1 % to 33%, on a particulate substrate by gas-phase deposition, comprising the steps of: a. Providing the particulate substrate in a reaction chamber; b. contacting the particulate substrate with a mixture of a vaporised Ti precursor gas and of a vaporised Mo precursor gas, thereby forming a layer of Ti and Mo precursor material on the particulate substrate; c. contacting the layer of Ti and Mo precursor material with a vaporized oxidant to allow the oxidant to react with the layer of Ti and Mo precursor material on the particulate substrate at a temperature Ti allowing for removal of the ligands from the respective precursor, yielding a Ti-doped MoOxlayer on the surface of the substrate; d. carrying out steps b. - c. for a natural number n a 1 of cycles so as to stack one or more layers of a conductive, Ti- doped MoOxcoating on the outer surface of the particular substrate material until a Ti- doped MoOxcoating of thickness di between 0.1 and 50 nm as determined by transmission electron microscopy (TEM) is obtained on the particular substrate material; and e. annealing the coating at elevated temperatures T2.

[0039] The expression “Ti-doped MoOxcoating” as used herein refers to a coating comprising Ti, Mo and O in varying amounts. More in particular, the term “Ti-doped” as used herein is not meant to restrict the coatings to compositions merely comprising relatively little amounts of Titanium. Rather, coatings according to the present invention may even comprise substantial amounts of Titanium. The Ti:Mo ratio in mol% may be between 1% to 99%, 1% to 66%, 1% to 33%.

[0040] Preferably the Ti:Mo ratio in mol % is between 1 % and 33%, more preferably between 5% and 33%

[0041] The coating is preferably a continuous closed layer. It can, however, also be a partial coverage or clusters, depending on the support material and / orthickness. The coatings so applied to particulate substrates can comprise comparably high contents of Titanium without phase separation, and in a way that offers precise control over film thickness, composition, and uniformity of the coating so applied, which is critical for applications requiring high performance, such as in electrochemical cells. Afurther advantage is the ability to provide defect-free coatings, and to conformally coat complex geometries, such as encountered in irregularly formed particulate substrates. The method also allows for good scalability and reproducibility essential for industrial production. The ability to fine-tune deposition parameters, such as temperatures, precursor flow rates, pressure, etc. ensures consistent film properties across large batches. The coating moreover enables to use of non-conductive particulate substrates to form conductive core-shell particles with improved stability towards the harsh conditions encountered within an electrochemical cell. The method thus enables the preparation of a conductive particle with the core of which may consist of an abundant and hence cheap material, such as Al2O3orTiCh, thus saving resources such as the more expensive Mo material used in the shell. Moreover, the method enables the provision of Ti-doped MoOxcoatings with an index number x within a range of between 2 and 3, including substantially below 3. This is particularly useful in scenarios in which the substrate is used as a support for a catalyst such as IrOx which may benefit from a lower oxidation state of the Molybdenum in the substrate supporting it. Compared to non-conductive core particles of core-shell particles coated with a conductive layer of a catalyst material such as an I rOxlayer, less catalyst material is required to arrive at a conductive particle useful in a PEM cell, as the shell of the particle is already conductive. Irrespective thereof, the core-shell particles obtainable by the method according to the invention can be used for many other applications, e.g. as a conductive core-shell particle in the electrodes of batteries. It is possible to fine-tune the index x in this context, so that it may be adapted to the needs depending on the application envisaged. Also, the Ti:Mo ratio may be fine-tuned as required and needed.

[0042] The method may comprise additional steps. For instance, the method may, priorto step e. comprise the additional steps (a.s.) of: a.s. i. carrying out step b., and a.s. ii. contacting the layer of Ti and Mo precursor material with a vaporized oxidant. In this case, the last layer of precursor material is subjected directly to the annealing step, which may save time and resources and is therefore interesting for economic reasons.

[0043] Preferably the method comprises at least one step of removing excess gases and / or byproducts from the reaction chamber byflushing the reaction chamber with an inert fluid or gas, preferably an inert gas chosen from Ar or N2, most preferably N2.

[0044] Using inert gases to clean the reaction mixture between two steps generally leads to cleaner reaction environments. Depending on the precursors used this may either be required or unnecessary.

[0045] The method may be carried out in one or more of different types of reactors, including, but not limited to a fixed bed reactor, a fluidized bed reactor, a semi-continuous type stacked fluidized bed reactor, a continuous type vibrating bed reactor, a rotary drum reactor, a continuous-type pneumatic transport reactor.

[0046] Preferably, the particulate substrate is chosen from among metals, inorganic metal oxides, metal carbides, metal nitrides, carbons and silicon, preferably, selected from titania (TiO2), Nb-doped titanium oxide (NbxTii-xO2), titanium nitride (TiN), titanium carbide (TiC), titanium boride (Ti B2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), tin dioxide (SnO2), F-doped tin oxide (FTO), Sb-doped tin oxide (ATO), In-doped tin oxide (ITO), Ta-doped tin oxide (TaTO), ceria (CeO2), ceria doped zirconia (CeO2 / ZrO2), niobium pentoxide (Nb2O5), niobium carbide (NbC) tantalum (Ta), tantalum pentoxide (Ta2Os), tantalum carbide (TaC), tungsten (W), tungsten oxide (WO3), tungsten carbide (WC), hafnium oxide (HfO2), bismuth oxide (Bi2O3), germanium oxide (GeO2); and mixtures and combinations thereof; or composites of boron carbide with other compounds, such as silicon boron carbide; or natural or artificial graphite, silicon, or Li-ion battery active materials such as layered oxides (LiCoO2(lithium cobalt oxide), LiNixMnYCo1-x-YO2( nickel-manganese-cobalt oxide), LiNixCoxAl1-2XO2(nickel-cobalt-aluminum oxide), spinel oxides (LiMn2O4lithium manganese oxide, LiM .s Nio.504 (lithium manganese nickel oxide)), polyanionic compounds (LiFePO4lithium iron phosphate, LiVP04F (lithium vanadium phosphate fluoride), or Na-ion active battery materials such as layered oxides (NaxCoO2(sodium cobalt oxide), NaxNi0.5Mn0.5O2(nickel- manganese-based Layered oxides), NaxFe0.5Mn0.5O2(iron based manganese layered oxides), polyanionic compounds (Na3V2(PO4)3(sodium vanadium phosphate), NaFeP04(sodium iron phosphate), Na2FePO4F (iron phosphate fluoride)), Prussian blue analogues (Na2MnFe(CN)6NaxFe[Fe(CN)s]) and hydrogen fuel cell particulate support materials, such as activated carbon and platinum coated carbon materials

[0047] As a Ti-doped MoOxcoating is more stable to harsh environments than many particulate substrate materials mentioned, it may impart stability on corresponding particles, while assuring conductivity of the outer Layer or shell of the respective particle which can be advantageous. In any event this increases the possibilities to create materials useful for further research and applications.

[0048] Preferably, the particulate substrate material is chosen from among titania (TiO2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), tin dioxide (SnO2), F-doped tin oxide (SnO2 / F), ceria (CeO2), ceria doped zirconia (CeO2 / ZrO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5); and mixtures and combinations thereof, more preferred from among titania (TiO2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), tin dioxide (SnO2), most preferably from among titania (TiO2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), wherein ZrO2is the most preferred.

[0049] Preferably the particulate substrate material has a weight average particle size in the range of either from 10 nm to 100 nm, preferably from 40 nm to 60 nm, or in the range of from 0.1 pm to 50 pm, preferably from 1 pm to 30 pm.

[0050] Particulate substrate material with a weight average particle size in the range of from 10 nm to 100 nm, preferably from 40 nm to 60 nm is particularly suitable in applications in which the particulate substrate material is to be used in a PEM of an electrolyzer.

[0051] Particulate substrate material with a weight average particle size in the range of from 0.1 pm to 50 pm, preferably of from 1 pm to 30 pm is particularly well suited for use in applications such as in battery electrodes. Preferably, the particulate substrate material has a particle size distribution s 100 nm as measured by Transmission Electron Microscopy (TEM).

[0052] Preferably, the coated particulate substrate has improved corrosion stability, as determined by a relative mass change of less than 10% of the coated particulate substrate after suspension for 24h in 0.5M H2SO4 at 80 °C.

[0053] The Ti precursor may be chosen from among usual Ti precursors, including, but not limited to a Ti halide or an organometallic Ti complex, such as TiCU, Ti(NMe2)4, Ti(NEt2)4, Tetrakis(propan-2-olato)titanium(IV), Tetrakis(ethoxido)titanium(IV), Tetrakis(tert- butoxido)titanium(IV), Ti(MeCp)(OMe)3, Ti(Me5Cp)(OMe)3, TiCp(NMe3)2, TiMe5Cp(NMe2)3. Preferably the precursor is chosen from among Ti(MeCp)(OMe)3, Ti(Me5Cp)(OMe)3, TiCp(NMe3)2, Ti(Me5Cp)(NMe2)3.

[0054] The Mo precursor may be chosen from among usual Mo precursors, including, but not limited to Mo halides, an organometallic Mo compound, or Mo complexes, such as Mo(CO)e, M0CI5, MOF6, Mo(NMe2)4 Tetrakis(N,N-dimethylamido)molybdenum, Mo(thd)2(thd = 2,2,6,6-tetramethylheptane-3,5-dione), cycloheptatriene molybdenum tricarbonyl, pentamethyl-cyclopentadienylmolybdenum dicarbonyl dimer and derivates, bis(alkylimido)-bis(alkylamido)molybdenum compounds or a molybdenum(O) precursor comprising at least one cycloheptatriene ligand and optionally one or more neutral ligands, wherein each neutral ligand is coordinated by carbon, nitrogen or phosphorus, or (NfBu)2(NMe2)2Mo (Bis(t-butylimido)bis(dimethylamino)molybdenum), Mo(=O)2(NR2)2, MO(=NR)2(OR)2, wherein R is H, a C1-6 alkyl group or SiR’3, wherein R’ is H or a C1-6 alkyl group, such as e.g. Mo(=NtBu2)2(OiPr)2, Mo(=NtBu2)2(OtBu)2, Mo(=NtBu2)2(OEt)2, Mo(=NtBu2)2(N(SiMe3)2)2, or Molybdenum imido alkyl / allyl complexes such as e.g.

[0055] Mo(NtBu)2(CH2SiMe3)2, Mo(NtBu)2Me2, Mo(NtBu)2(allyl)2, and the like.

[0056] Preferably, the Mo precursors is chosen from among Mo(=NtBu2)2(OiPr)2, Mo(=NtBu2)2(OtBu)2, Mo(=NtBu2)2(OEt)2, Mo(=NtBu2)2(N(SiMe3)2)2, Mo(NtBu)2(CH2SiMe3)2, Mo(NtBu)2Me2, Mo(NtBu)2(allyl)2. Preferably, steps b. and c. are carried out for a number n > 1 of cycles.

[0057] It is further preferred that steps b. to c. are carried out for a number n > 1 of cycles, and that following each step a., b. and / or c., the reaction chamber is flushed with an inert fluid or gas so as to remove contamination from the gas phase, such as left-over contamination with Ti or Mo precursor material, oxidants, and / or by-products from the gas phase prior to starting the next step and / or cycle.

[0058] Preferably, the method is carried out for a number n>1 of cycles wherein in the range of from 2 to 200, 2 to 100, 2 to 80, 2 to 70, 2 to 35, 2 to 16, 2 to 12, 4 to 10, 6 to 9, or 7 to 8 cycles.

[0059] Preferably, the method is carried out for a number n of cycles sufficient to achieve an essentially uninterrupted and closed coating separating the particulate substrate material from the exterior.

[0060] Preferably, the method is a method wherein the resulting Ti-doped MoOxcoated particulate substrate has an electrical conductivity of 10-6to 10'2S / cm as detected by powder conductivity measurements.

[0061] Preferably, the method is a method wherein the resulting Ti-doped MoOxcoated particulate substrate has an electrical conductivity which is increased by the 10 to 10000- fold as compared to the electrical conductivity of the uncoated particulate substrate as respectively detected by powder conductivity measurements.

[0062] The temperature Ti is preferably between 200 and 300°C, between 220 and 280°C, between 240 and 260°C, or around 250°C.

[0063] The thickness di is preferably between 0.1 and 40 nm, or between 2 and 18 nm.

[0064] The temperature T2is preferably between 250 and 500 °C or from 250 to 700 °C, more preferably from 450 to 700°C, and most preferably between 550 and 700 °C. Preferably, the temperature T2is between 250 and 500 °C or from 250 to 700 °C, more preferably from 450 to 700°C, and most preferably between 550 and 700 °C, and the temperature T2is elevated at a heating ramp rate rhrof between 1 and 8 °C min-1, followed by 3 hours of soaking time at the maximum temperature.

[0065] It is further preferred that the temperature T2is between 250 and 500 °C or from 250 to 700 °C, more preferably from 450 to 700°C, and most preferably between 550 and 700 °C, and that the temperature is elevated at a heating ramp rate rhrof between 3 and 6 °C min-1, followed by 3 hours of soaking time at the maximum temperature.

[0066] It is further preferred, that the temperature T2is between 250 and 500 °C or from 250 to 700 °C, more preferably from 450 to 700°C, and most preferably between 550 and 700 °C, and that the temperature is elevated at a heating ramp rate rhrof 4 °C min-1, followed by 3 hours of soaking time at the maximum temperature.

[0067] The particulate substrate according to the second aspect of the present invention is a particulate substrate material comprising a conductive layer of a Ti-doped MoOxcoating, wherein 2 s x s 3, of thickness di which is obtainable by a method according to the first aspect of the present invention.

[0068] The advantages of such core-shell particles over those of the prior art have been discussed above in relation to the method according to the first aspect of the present invention.

[0069] Further aspects of the present invention are accordingly the use of a particulate substrate material accordingto the second aspect of the present invention as a support for a catalytic material. It is particularly useful and hence preferred to use the particle as a support for lrOxcatalysts deposited thereupon, e.g. by methods such as described in Dutch Patent Application NL2036587, which is incorporated herein by reference, and / orto the use of a particulate substrate material according to the second aspect of the present invention as a conductive surface layer in an electrochemical cell. In the following, the present invention will be further explained by making reference to the following Figures and Examples.

[0070] Brief description of the Figures

[0071] The figures show in

[0072] Fig. 1 a graph showing the value of index x as determined by X-ray photoelectron spectroscopy (XPS) versus the content of Ti to Mo ratio in mole % in the coating of several samples of core-shell particles obtained by a method according to the present invention; Fig. 2 Transmission Electron Microscopy (TEM) images of (from left to right) an uncoated particulate substrate, a coated particulate substrate not yet having been subjected to an annealing step according to the present invention, and the same coated particulate substrate according the present invention;

[0073] Fig. 3 X-Ray diffraction patterns of two distinct samples of particulate core-shell particles according to the present invention; and, in

[0074] Fig. 4 a schematic representation of electrodes as typically used fuel / electrolyzer cells vers, electrodes as typically used in battery cells.

[0075] The invention will in the following be described in more detail by making reference to the Examples and to Fig. 1 to 4.

[0076] Detailed description and Examples

[0077] Examples:

[0078] Coating process

[0079] To perform the gas-phase deposition, 10 g of a particulate ZrO2substrate powder is loaded into a ~200 ml reactor column with a porous frit on the inlet and outlet to prevent particulate powder from escaping the reactor. The reactor column is connected to gas inlet and outlet lines and placed on a vibrating table. The column is vibrated between 0.1 - 50 Hz. The gas inlets are connected to precursor vessels that contain the molybdenum precursor, the titanium precursor and oxygen sources. The vessels are heated at different temperatures to achieve sufficient vapor pressure of the respective precursors.

[0080] The titanium precursor is Ti(MesCp)(OMe)3. The molybdenum precursor is Mo(=NtBu2)2(OtBu)2.

[0081] The reactor column is heated to 250 °C while the powder is fluidized using an inert nitrogen or precursor gas at a flow of 0.1 to 1 L min-1. The reactor pressure is kept near atmospheric pressure.

[0082] A cycle to form a monolayer (0.05 - 0.1 nm) of coating constitutes the following:

[0083] In the first step (1) molybdenum and titanium gas-phase precursors are introduced via the inlet by flowing nitrogen gas through the precursor vessels. The total precursor flow is kept constant at 1 L min-1. The ratio of molybdenum and titanium gas flow are kept at a 1 :1 ratio (i.e. 0.5 L min-1each). This step is performed for a certain amount of time until most of the available sites on the powder have reacted with the precursors. Next, an inert gas is flown into the reactor to remove any by-products or unreacted precursors. Then, in the second step (2), the oxygen co-reactants are introduced and reacted with the powder for a specific time until the ligands of the molybdenum and titanium ligands are mostly reacted away. In this example, both oxygen gas and water vapor are introduced into the reactor simultaneously, with a total flow of 1 L min-1. Then an inert gas is flown again for a specific time to remove the byproducts or unreacted oxygen co-reactants.

[0084] By repeating steps 1 and 2, a thicker coating layer can be achieved. After completing the process, the powder is collected and used for further analysis.

[0085] In order to vary the Ti to Mo atomic %, the temperature of the precursor vessels was modified.

[0086] The conditions as shown in the following table 1 were applied. Table 1 further includes the results of the obtained Ti and Mo wt% in the powder (as measured by Inductively Coupled Plasma- Optical Emission Spectroscopy, ICP-OES) and the corresponding calculated Ti:Mo molar ratio in the coating. Note that the Ti and Mo wt% correspond to their fraction in the whole powder sample (including the ZrO2cores). ICP-OES was performed on a standard iCAP PRO Series ICP-OES from Thermo Scientific. The following table 1 summarizes the conditions and results obtained forfour distinct Examples, which correspond to intermediates as obtained prior to the annealing step e. according to the present invention, i.e. following steps a.-d..

[0087] Table 1

[0088] It is clearthat a wide range of Ti:Mo can be achieved in this manner. It must be noted that the same effect of varying Ti content could also be achieved by changing the ratio of the molybdenum to titanium gas flow.

[0089] Post-coating annealing

[0090] To further tune the properties of the coating, such as crystallinity, and mainly reduce the oxidation state of the molybdenum, annealing correspondingto step e. of the method according to the invention as claimed is performed. The conditions as shown in the following table 2 were tested:

[0091]

[0092] Table 2: Annealing conditions

[0093] The annealing procedure was carried out as follows:

[0094] The various samples were loaded into sample tubes and analyzed using a Quantachrome Autosorb IQ. A continuous flow of pure nitrogen gas (N2) or 10% H290% Ar was passed through the powder bed at a rate of 40 ml / min. The temperature was increased to 400-700 °C (namely to 450, 550, 600, 700 °C as may be taken from Table 2 above) at a rate of 5 °C per minute. Once the target temperature of 400-700 °C was reached, it was maintained for a duration of 2-4 hours. After this period, the sample tubes were removed from the oven and allowed to cool to room temperature.

[0095] X-ray photoelectron spectroscopy (XPS) studies were done to investigate the molybdenum oxidation state after annealing. This was done by fitting the Mo(VI), Mo(V), Mo(IV) peaks, and calculating the amount of oxygen needed to keep charge neutrality. The result can be seen in the plot of the values x plotted against the Ti:Mo (mol:mol) as seen in Fig. 1 . As can be deduced from Fig. 1 , in general, annealing reduces the amount x of oxygen per molybdenum in the coating considerably, namely from about 2.8 to down to 2.4. In some cases, the 10% hydrogen annealing (program #2) seems more effective at reducing the amount of oxygen than pure nitrogen (program #1), whereas in other cases, program #2 was more effective. Applicants further observe that more elevated temperatures T2would appear to further increase the efficiency of reduction (programs #3 and #4), as have been observed to yield samples with particularly good conductivity values (see below). Physical characterization of coatings

[0096] Transmission Electron Microscopy (TEM)

[0097] After coating of the ZrO2powder with the Ti / MoOxlayer, the coatings were characterized using TEM. Fig. 2 shows Transmission Electron Microscopy (TEM) images of (from left to right) of an uncoated particulate substrate, a coated particulate substrate (of sample NE01 -005) not yet having been subjected to an annealing step according to the present invention, and the same coated particulate substrate following an annealing step (i.e. of sample NE01 -005_H2) accordingto the present invention. As seen from Fig. 2, a clear change in contrast is seen after coating the ZrO2support material. For NE01-005 and NE01 -005_H2, a closed coating layer on the surface can be discerned. In both NE01 -005 and NE01 -005_H2, the layer is about 4-8 nm in thickness

[0098] XRD of coated and annealed sample

[0099] Fig. 3 presents the diffraction patterns of the two coated examples, as-coated and annealed respectively. The diffraction patterns were modelled with the crystal structure of Baddeleyite (ZrO2) and Tugarinovite (MoO2). The Baddeleyite is attributed to the ZrO2powder support, whereas the Tugarinovite to the coating layer. A crystal structure related to the TiO2was not visible, which shows that the titanium dopant does not phase separate out of the MOO2layer. The method according to the present invention thus achieves high levels of Ti dopant in MoO2without phase separation, in contrast to what is known in the prior art.

[0100] The diffraction patterns in Fig. 3 do not match the baseline, which indicates that there is still amorph material present in the powders. The annealed samples show some peaks with increased intensity.

[0101] Compared to the modelled Baddeleyite and Tugarinovite, this indicates that more Tugarinovite is present after annealing. Table 3 below shows the quantitative bulk mineralogical composition of the samples (in mass percentages of the identified crystalline substances). Even after annealing, no TiO2crystal phases were present in the sample.

[0102] Table 3: Quantitative bulk mineralogical composition of samples shown in Fig. 3

[0103] Conductivity of the Mo / Ti coated powder

[0104] Samples were tested under conditions of 22 ± 1 °C and 47 ± 3% relative humidity. The apparatus employed for the measurements featured two pistons, between which the powdered samples were positioned. The setup used had a 3 mm diameter, with the height of the sample being determined using a TESA dial gauge. Both the voltage application and current measurement were carried out using a Keithley 6517B electrometer. A pressure of 250 g per weight was applied, which is reported in the results as pressure in kPa. The samples were first placed on the measurement setup, and a pressure of 354 kPa was applied for each measurement. Following the application of pressure, the current was given 1 minute to stabilize before recording the resistivity and sample height.

[0105] Subsequently, an additional 250 g weight was added, and after another 1 -minute stabilization period, the resistivity and height were recorded again. This process was repeated until a total of 16 weights were applied to the setup.

[0106] The resistivity was determined by applying Ohm’s Law, dividing the voltage by the current. The electrical conductivity was calculated using the formula, which involved dividing the height by the surface area of the device and multiplying by the resistivity. The specific equation used is: o = electrical conductivity (S / cm) t = Height of powder bed (cm)

[0107] Rt= Resistivity (Q)

[0108] A = Surface area of the piston (cm2)

[0109] In table 4 below, the value of the conductivity is given for the different examples as a function of oxygen content in MoOx. As can be seen, the lower the oxygen content, the higher the conductivity. This is in line with the theory that predicts a higher conductivity the more Mo(IV) is present. Importantly, coating of the uncoated ZrO2with the Ti / MoOxlayer shows an increase in conductivity of the uncoated ZrO2powder by more than 3 orders of magnitude.

[0110] Table 4: Conductivity vs. x of Examples; *: see remark in text below; **: as summarized in

[0111] Table 2 above Regarding x in MoOxfor pure commercial MoO2powder, the result can be explained by the fact that XPS only addresses the first few nanometers of the surface of materials. It is well- known that the surface is often more oxidized than the bulk of a material, hence the value for the bulk is most likely closer to 2. Since the films of the samples investigated are 4-12 nm thick, x in MoOxin the other samples is more reflective of the average composition of the respective layer.

[0112] Regarding the samples NE01 -007_2_3_N2 and NE04-003_H2_550, wherein x is yet undetermined: Without wanting to be bound by theory, but based on the conductivity values of samples NE01 -007_2_3_N2 and NE04-003_H2_550, applicant is confident that the value of x in these samples is considerably lower than in samples N01 -007, N01- 007_N2 and N01 -007_H2 and / or that the coating in these samples is more crystalline.

[0113] The conductivity values as summarized in Table 4 further show that reduction during the annealing is more effective in the presence of H2as compared to in the presence of N2. Irrespective thereof, the data show that increasing the annealing temperature can have a beneficial effect, as evidenced by the fact that the samples in table 4 have undergone annealing under different conditions #1 -#4 as have been detailed in Table 2 above.

[0114] Corrosion protection

[0115] The corrosion protection benefits were tested as follows. Representative sample NE01 - 007_H2 was added to a beaker containing 0.5M H2SO4 at 80 °C. Aliquots of the resulting suspension were taken at 2, 4, 6 and 24 hours, filtered and further analysed by ICP-OES.

[0116] The amount of Zr from the support was determined, which is a measure the corrosion protective benefits of the coating layers. The less Zr in the solution, the better the coating layer was in protecting the support. A summary of the results is found in table 5 below. From the results, it was seen that no Zr could be determined as a result of corrosion in acidic environment, giving evidence of the corrosion protective properties of the Ti / MoOxlayer. t (h) Zr (ICP-OES)

[0117] 2 below detection limit

[0118] 4 below detection limit

[0119] 6 below detection limit

[0120] 24 below detection limit

[0121] Table 5: Corrosion test results.

[0122] Benefits of conductive layers

[0123] In most types of electrochemical cells, the electrode's active components consist of particles, as is schematically represented in Fig. 4. The electrode needs to conduct electrons to and from the active components depending on the redox process. By applying a conductive and corrosion-resistant shell to the active particles, the activity of the electrochemical cell can be enhanced by lowering the internal resistance of the electrodes, while preventing dissolution of the core particles.

Claims

Claims1 . A method for producing a conductive, Ti-doped MoOxcoating, wherein 2 < x < 3 and wherein the Ti:Mo ratio in mol% is between 1 % to 99%, 1 % to 66% or 1 % to 33%, on a particulate substrate by gas-phase deposition, comprising the steps of: a. Providing the particulate substrate in a reaction chamber; b. contacting the particulate substrate with a mixture of a vaporised Ti precursor gas and of a vaporised Mo precursor gas, thereby forming a layer of Ti and Mo precursor material on the particulate substrate; c. contacting the layer of Ti and Mo precursor material with a vaporized oxidant to allow the oxidant to react with the layer of Ti and Mo precursor material on the particulate substrate at a temperature allowing for removal of the ligands from the respective precursor, yielding a Ti-doped MoOxlayer on the surface of the substrate; d. carrying out steps b. - c. for a natural number n a 1 of cycles so as to stack one or more layers of a conductive, Ti-doped MoOxcoating on the outer surface of the particular substrate material until a Ti-doped MoOxcoating of thickness di between 0.1 and 50 nm as determined by transmission electron microscopy (TEM) is obtained on the particular substrate material; and e. annealing the coating at elevated temperatures T2.

2. The method according to claim 1 , comprising, prior to step e. the additional step (a.s.) of: a.s. i. carrying out step b. a.s. ii. contacting the layer of Ti and Mo precursor material with a vaporized oxidant.

3. The method according to any one of the preceding claims, wherein the Ti:Mo ratio of the coating in mol % is between 1 % and 33%, more preferably between 5% and 33%.

4. The method according to any one of the preceding claims, wherein the coating is a continuous closed layer.

5. The method according to any one of the preceding claims, comprising at least one step of removing excess gases and / or by-products from the reaction chamber by flushing the reaction chamber with an inert fluid or gas, preferably an inert gas chosen from Ar or N2, most preferably N2.

6. The method according to any one of the preceding claims, performed in one or more of a fluidized bed reactor, a batch-type fluidized bed reactor, a semi-continuous type stacked fluidized bed reactor, a continuous type vibrating bed reactor, a rotary drum reactor, a continuous-type pneumatic transport reactor.

7. The method according to any one of the preceding claims, wherein the particulate substrate material is chosen from among metals, inorganic metal oxides, metal carbides, metal nitrides, carbons and silicon, preferably, selected from titania (TiO2), Nb-doped titanium oxide (NbxTii.xO2), titanium nitride (TIN), titanium carbide (TiC), titanium boride (TiB2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), tin dioxide (SnO2), F-doped tin oxide (FTO), Sb-doped tin oxide (ATO), In-doped tin oxide (ITO), Ta-doped tin oxide (TaTO), ceria (CeO2), ceria doped zirconia (CeO2 / ZrO2), niobium pentoxide (Nb2O5), niobium carbide (NbC) tantalum (Ta), tantalum pentoxide (Ta2O5), tantalum carbide (TaC), tungsten (W), tungsten oxide (WO3), tungsten carbide (WC), hafnium oxide (HfO2), bismuth oxide (Bi2O3), germanium oxide (GeO2); and mixtures and combinations thereof; or composites of boron carbide with other compounds, such as silicon boron carbide; or natural or artificial graphite, silicon, or Li-ion battery active materials such as layered oxides (LiCoO2(lithium cobalt oxide), LiNixMnYCo1-x-YO2( nickel-manganese-cobalt oxide), LiNixCoxAl1-2XO2(nickel-cobalt-aluminum oxide), spinel oxides (LiMn2O4lithium manganese oxide, LiM .s Nio.sCL (lithium manganese nickel oxide)), polyanionic compounds (LiFeP04lithium iron phosphate, LiVPO4F (lithium vanadium phosphate fluoride), or Na-ion active battery materials such as layered oxides (NaxCoO2(sodium cobalt oxide), NaxNi0.5Mn0.5O2(nickel-manganese-based layered oxides), NaxFe0.5Mn0.5O2(ironbased manganese layered oxides), polyanionic compounds (Na3V2(PO4)3(sodium vanadium phosphate), NaFeP04(sodium iron phosphate), Na2FePO4F (iron phosphate fluoride)), Prussian blue analogues (Na2MnFe(CN)6NaxFe[Fe(CN)6]) and hydrogen fuel cell particulate support materials, such as activated carbon and platinum coated carbon materials.

8. The method according to any one of the preceding claims, wherein the particulate substrate material is chosen from among titania (TiO2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), tin dioxide (SnO2), F-doped tin oxide (SnO2 / F), ceria (CeO2), ceria doped zirconia (CeO2 / ZrO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5); and mixtures and combinations thereof, more preferred from among titania (TiO2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), tin dioxide (SnO2), most preferably from among titania (TiO2), silica (SiO2), alumina (Al2O3), zirconia (ZrO2), wherein ZrO2is the most preferred.

9. The method according to any one of the preceding claims, wherein the particulate substrate material has a weight average particle size is in the range of either from 10 nm to 100 nm, preferably of from 40 nm to 60 nm, or in the range of from 0.1 pm to 50 pm, preferably of from 1 pm to 30 pm.

10. The method according to any one of the preceding claims, wherein the particulate substrate material has a particle size distribution s 100 nm as determined by Transmission Electron Microscopy (TEM).11 . The method according to any one of the preceding claims, wherein the coated particulate substrate has improved corrosion stability, as determined by a relative mass change of less than 10% of the coated particulate substrate after suspension for 24h in 0.5M H2SO4at 80 °C12. The method according to any one of the preceding claims, wherein the Ti precursor is chosen from among a Ti halide or an organometallic Ti complex, such as TiCU, Ti(NMe2)4,Ti(NEt2)4, Tetrakis(propan-2-olato)titanium(IV),Tetrakis(ethoxido)titanium(IV), Tetrakis(tert-butoxido)titanium(IV), Ti(Me5Cp)(OMe)3.

13. The method according to any one of the preceding claims, wherein the Ti precursors is chosen from among Ti(MeCp)(OMe)3, Ti(Me5Cp)(OMe)3, Ti(Cp(NMe3)2, Ti(Me5Cp)(NMe2)3.

14. The method according to any one of the preceding claims, wherein the Mo precursor is chosen from among usual Mo precursors, including, but not limited to Mo halides, an organometallic Mo compound, or Mo complexes, such as Mo(CO)s, M0CI5, MOF6, Mo(NMe2)4 Tetrakis(N,N-dimethylamido)molybdenum, Mo(thd)2 (thd = 2,2,6,6-tetramethylheptane-3,5-dione), cycloheptatriene molybdenum tricarbonyl, pentamethyl-cyclopentadienylmolybdenum dicarbonyl dimer and derivates, bis(alkylimido)-bis(alkylamido)molybdenum compounds or a molybdenum(O) precursor comprising at least one cycloheptatriene ligand and optionally one or more neutral ligands, wherein each neutral ligand is coordinated by carbon, nitrogen or phosphorus, or (NtBu)2(NMe2)2Mo (Bis(t- butylimido)bis(dimethylamino)molybdenum), Mo(=O)2(NR2)2, Mo(=NR)2(OR)2, wherein R is H, a Ci.6alkyl group or SiR’3, wherein R’ is H or a Ci.6alkyl group, such as e.g. Mo(=NtBu2)2(OiPr)2, Mo(=NtBu2)2(OtBu)2, Mo(=NtBu2)2(OEt)2, Mo(=NtBu2)2(N(SiMe3)2)2, or Molybdenum imido alkyl / allyl complexes such as e.g. Mo(NtBu)2(CH2SiMe3)2, Mo(NtBu)2Me2, Mo(NtBu)2(allyl)2, and the like.

15. The method according to any one of the preceding claims, wherein the Mo precursor is chosen from among Mo(=NtBu2)2(OiPr)2, Mo(=NtBu2)2(OtBu)2, Mo(=NtBu2)2(OEt)2, Mo(=NtBu2)2(N(SiMe3)2)2, Mo(NtBu)2(CH2SiMe3)2, Mo(NtBu)2Me2, Mo(NtBu)2(allyl)2.

16. The method according to any one of the preceding claims, wherein steps b. and c. are carried out for a number n > 1 of cycles.

17. The method according to any one of the preceding claims, wherein steps b. to c. are carried out for a number n > 1 of cycles, and wherein following each step a., b. and / or c., the reaction chamber is flushed with an inert fluid or gas so as to remove contamination from the gas phase, such as left-over contamination with Ti or Mo precursor material, oxidants, and / or by-products from the gas phase prior to starting the next step and / or cycle.

18. The method according to any one of the preceding claims, wherein the method is carried out for a number n>1 of cycles wherein in the range of from 2 to 200, 2 to100, 2 to 80, 2 to 70, 2 to 35, 2 to 16, 2 to 12, 4 to 10, 6 to 9, or 7 to 8 cycles.

19. The method according to any one of the preceding claims, wherein the method is carried out for a number n of cycles sufficient to achieve an essentially uninterrupted and closed coating separating the particulate substrate material from the exterior.

20. The method according to any one of the preceding claims, wherein the resulting Ti- doped MoOxcoated particulate substrate has an electrical conductivity of 10 ® to 10_2S / cm as detected by powder conductivity measurements.21 . The method according to any one of the preceding claims, wherein the resulting Ti- doped MoOxcoated particulate substrate has an electrical conductivity which is increased by the 10 to 10000-fold as compared to the electrical conductivity of the uncoated particulate substrate as respectively detected by powder conductivity measurements.

22. The method according to any one of the preceding claims, wherein the temperature Ti is between 200 and 300°C.

23. The method according to any one of the preceding claims, wherein the temperatureTi is between 220 and 280°C.

24. The method according to any one of the preceding claims, wherein the temperature Ti is between 240 and 260°C.

25. The method according to any one of the preceding claims, wherein the temperature Ti is around 250°C.

26. The method according to any one of the preceding claims, wherein the thickness di is between 0.1 and 40 nm.

27. The method according to any one of the preceding claims, wherein the thickness di is between 2 and 18 nm.

28. The method according to any one of the preceding claims, wherein the temperature T2is from 250 to 700 °C.

29. The method according to any one of the preceding claims, wherein the temperature T2is from 250 to 700 °C, and wherein the temperature T2is elevated at a heating ramp rate rhrof between 1 and 8 °C min"1, followed by 3 hours of soaking time at the maximum temperature.

30. The method according to any one of the preceding claims, wherein the temperature T2is from 250 to 700 °C, and wherein the temperature is elevated at a heating ramp rate rhrof between 3 and 6 °C min-1, followed by 3 hours of soaking time at the maximum temperature.31 . The method according to any one of the preceding claims, wherein the temperature T2is from 250 to 700 °C, and wherein the temperature is elevated at a heating ramp rate rhrof 4 °C min-1, followed by 3 hours of soaking time at the maximum temperature.27.

32. A particulate substrate material comprising a conductive layer of a Ti-doped MoOxcoating, wherein 2 s x s 3, of thickness di obtainable by a process according to any one of the preceding claims.

33. Use of a particulate substrate material according to claim 32 as a support for a catalytic material.

34. Use of a particulate substrate material according to claim 32 as a conductive material in an electrochemical cell.

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