Photoelectrochemical converter

Abstract

The invention relates to a photoelectrochemical converter (1) comprising a PIN-type photovoltaic cell (3) and an electrochemical module (2) attached to the photovoltaic cell, wherein the electrochemical module comprises anode (20) and cathode (21) blocks, and an electrolysis cell (22) sandwiched between the anode and cathode blocks, wherein the electrolysis cell is supplied with electrical power by the photovoltaic cell in order to oxidise water, wherein the photoelectrochemical converter comprises a water inlet opening (32) formed on the anode block in order to add water to the converter, wherein the electrolysis cell comprises a stack containing an anode (23), a proton exchange membrane (25) and a cathode (24), and wherein the anode block (20) is sandwiched between the electrolysis cell (25) and the photovoltaic cell (3) and comprises an anode fluid circulation system (30) that comprises an anode exchange opening (31) that opens onto the anode (23) and an anode channel (30) shaped to convey water from the water inlet opening to the anode.

Description

[0001] Description

[0002] Title: Photoelectrochemical converter

[0003] Technical field of the invention

[0004] The present invention relates to a photoelectrochemical converter for at least dissociating water and generating a fluid of interest, in particular dihydrogen.

[0005] Description of the prior art

[0006] A photoelectrochemical converter is, for example, a device comprising an electrolysis cell and a photovoltaic cell converting light radiation into an electric current which electrically supplies the electrolysis cell.

[0007] The electrolysis cell consists of an anode and a cathode sandwiching an ion-exchange electrolytic membrane. Such a converter can oxidize water to generate hydrogen, using an electric current produced by the photovoltaic cell.

[0008] H2O -> 2 H + + 2 e' + 1 / 2 O2

[0009] H protons + cross the electrolytic membrane and reach the cathode where they are reduced according to the equation

[0010] 2 H + + 2 e' - H2

[0011] Thus, a gaseous release of dihydrogen is produced at the cathode which can then be stored for later use, for example as fuel to generate electrical energy within a fuel cell.

[0012] US 2022 / 0220623 Al, WO 2023 / 057374 Al, WO 2023 / 057376 Al, US 10,1006,130 B2, “Integrated halide perovskite photoelectrochemical cells with solar-driven water-splitting efficiency of 20.8%”, Austin MK Fehr et al., nature communications (2023)14:3797 doi: 10.1038 / s41467-023-39290-y, “Efficient Continuous Light-Driven Electrochemical Water Splitting Enabled by Monolithic Perovskite-Silicon Tandem Photovoltaics”, K. Datta et al., Adv. Mater. Technol. 2023, 8, 2201131, doi: 10.1002 / admt.202201131, “Integrated and Unassisted Solar Water-Splitting System by Monolithic Perovskite / Silicon Tandem Solar Cell”, Manjing Wang et al., Solar RRL, Vol. 6, #2, 2022, doi: 10.1002 / solr.202100748 describe different types of photoelectrochemical converters. These converters have at least one of the following disadvantages:

[0013] - the apparent difficulty of moving from the experimental prototype stage to the stage of a device produced on an industrial scale;

[0014] - a need for significant concentration of solar radiation to provide sufficient electrical energy to the electrolysis cell, the need for solar concentration being able to be accompanied by high production costs;

[0015] - a complex design which does not allow for a simple electrical connection between the photovoltaic cell and the electrolysis cell to be combined with an efficient distribution and extraction of the flows of reagent(s) and product(s) from the electrolysis.

[0016] There is therefore a need for a photoelectrochemical converter which can overcome at least one, preferably each, of these drawbacks.

[0017] Summary of the invention

[0018] The invention provides a photoelectrochemical converter comprising a PIN type photovoltaic cell and an electrochemical module fixed to the photovoltaic cell, the electrochemical module comprising an anode block, a cathode block and an electrolysis cell sandwiched between the anode block and the cathode block and which is electrically powered by the photovoltaic cell to at least oxidize water, the photoelectrochemical converter comprising a water inlet opening provided on one face of the anode block in order to introduce water into the converter, the electrolysis cell comprising a stack containing in succession, an anode, an ion exchange membrane and a cathode,the anode block being sandwiched between the electrolysis cell and the photovoltaic cell and comprising an anode fluid circulation system comprising an anode exchange opening which opens onto the anode and an anode channel shaped to transport water from the water inlet opening to the anode.,

[0019] The converter according to the invention is compact, the electrochemical module and the photovoltaic cell being fixed to each other. Since the PIN type photovoltaic cell and the electrolysis cell sandwich the anode block, the electrical connection between the photovoltaic cell and the anode is made easier. In addition, the flow of water in the anode fluid circulation system from the water inlet opening can be carried out in a sealed manner, limiting the risks of water and gas leakage, and their consequences on the performance of the converter, such as parasitic chemical reactions, clogging of the anode, flooding of the cathode, loss or recombination of gases, or damage to the photovoltaic cell. In particular, the converter according to the invention can allow water to flow only within the anode block, from its introduction into the converter until its extraction from the converter.Finally, the anode fluid circulation system being arranged between the photovoltaic cell and the anode, the water is heated directly by thermal transfer of the heat accumulated by the photovoltaic cell under the effect of solar radiation. The efficiency of the electrolysis of the water thus preheated is thus increased.

[0020] Furthermore, the specific conformation of the water inlet makes it possible, if necessary, to advantageously maximize the surface area of ​​the electrolysis cell covering the photovoltaic cell. Advantageously, it is thus possible to equip the converter with a photovoltaic cell not requiring a solar concentrator. The heating of the converter components can thus be limited, which reduces on the one hand the heat flux to be extracted and on the other hand the extreme local variations in thermal stresses during the day / night cycles which impact the lifetime of the device. Preferably, the photovoltaic cell covers more than 70%, preferably more than 80%, preferably more than 90%, preferably more than 95% of the area of ​​the anode and / or the cathode. Preferably, it completely covers the anode and / or the cathode.

[0021] Preferably, the photovoltaic cell covers more than 70%, preferably more than 80%, or even more than 90% of the area of ​​the face of the anode block on which it is superimposed. It may completely cover the face of the anode block on which it is superimposed.

[0022] By convention, a PIN type photovoltaic cell is such that a P layer of a PIN stack is the first layer formed during the manufacture of the photovoltaic cell. The P layer, being a provider of holes, i.e. positive charges, is electrically connected to the anode so that the holes photogenerated by the photovoltaic cell can be brought to the anode for the oxidation reactions. A PIN type photovoltaic cell may comprise a single PIN stack. Alternatively, it may comprise several PIN stacks arranged on top of each other. Preferably, the PIN type photovoltaic cell is a multijunction cell, in which the PIN stacks are arranged on top of each other and electrically connected in series, so as to deliver a sufficient voltage for the implementation of the electrochemical reactions. The multijunction cell may in particular be of the tandem type.

[0023] Preferably, the converter comprises a cover, the photovoltaic cell being entirely disposed between the cover and the electrochemical module.

[0024] The cover may include a frame defining a window superimposed on the photovoltaic cell. Thus, solar radiation can reach the photovoltaic cell through the window.

[0025] The cover preferably comprises a transparent protective plate, for example made of glass, covering the window, to protect the photovoltaic cell from impacts and / or bad weather. Alternatively, the photovoltaic cell comprises the transparent protective plate which is an external layer of the photovoltaic cell and is opposite the electrochemical module.

[0026] The cover, especially the frame, can be fixed on the electrochemical module, in particular on the anode block.

[0027] Preferably, the water inlet opening is distant from the cover, in particular from the frame.

[0028] Preferably, the water inlet opening is not superimposed on the cover, in particular it is not superimposed on the frame.

[0029] Preferably, the water inlet opening is distant from the photovoltaic cell. Preferably, the water inlet opening is not superimposed on the photovoltaic cell.

[0030] Preferably, the water inlet opening is provided on a side face of the anode block. A side face of the anode block connects the lower face of the anode block that faces the anode to the upper face of the anode block that faces the photovoltaic cell. Alternatively, the water inlet opening may be formed on the upper face of the anode block and is not superimposed on the cover and the photovoltaic cell.

[0031] The converter may have a water supply connection arranged in the water inlet opening, for connecting a water supply line. The water supply connection is for example screwed onto the anode block or is made integral with the anode block.

[0032] Preferably, the anode circulation system, in particular the anode channel, extends parallel to the electrolysis cell. In this way, it is possible to distribute a high water flow rate and to easily extract the oxygen produced at the anode without excessive and harmful formation of bubbles formed from said oxygen. Preferably, in order to facilitate both the extraction of oxygen and the collection of photons, the device is arranged such that the fluid circulation system forms an angle of between 10° and 90° with the horizontal. Said angle is preferably at least 30°. It may be less than 90°.

[0033] Preferably, the anode circulation system, in particular the anode channel, extends parallel to the photovoltaic cell. The heat transfer stored in the photovoltaic cell can thus be transmitted homogeneously to the water circulating in the anode fluid circulation system.

[0034] Preferably, the anode fluid circulation system extends from the water inlet opening to a water outlet opening provided on a face, preferably lateral and in particular opposite, of the anode block. Preferably, the water outlet opening opens out of the converter.

[0035] The water inlet opening and the water outlet opening may be provided on different, preferably opposite, side faces of the anode block. Alternatively, they may be provided on the same face, in particular a side face, of the anode block.

[0036] Preferably, the fluid circulation system comprises a plurality of anode channels. The anode channels are preferably shaped to generate a turbulent flow of water.

[0037] The fluid circulation system preferably comprises from upstream to downstream, from the water inlet opening to the water outlet opening, an anode inlet collecting chamber, the anode channels and an anode outlet collecting chamber, each anode channel opening at its opposite ends into the anode inlet collecting chamber and the anode outlet collecting chamber respectively. In this way, a high flow rate of turbulently flowing water can circulate which is suitable for optimal oxidation of the water at the anode while optimizing the heat exchange between the water and the photovoltaic cell.

[0038] For example, the anode inlet collecting chamber and / or the anode outlet collecting chamber has a groove shape extending perpendicular to the anode channels.

[0039] Preferably, the anode channels extend parallel to each other. Preferably, each anode channel opens onto the anode through a corresponding anode exchange opening.

[0040] Each anode opening preferably extends over more than 10%, preferably over more than 50%, preferably over more than 90% of the length of the corresponding anode channel, more preferably over the entire length of the corresponding anode channel.

[0041] The fluid circulation system can result from casting the anode block, machining the anode block, or additive manufacturing the anode block. Machining of the anode block can be mechanical, thermal, or chemical.

[0042] The anode channels may be grooves formed in the anode block and opening through the anode exchange opening on the face of the anode block opposite the anode.

[0043] The anodic channels can have a cross-section whose outline is polygonal, in particular rectangular, or in the form of a portion of an arc of a circle or an ellipse.

[0044] The anode channels may extend along a rectilinear axis. In particular, they may be rectilinear. According to one variant, the fluid circulation channels may follow a sinuous, for example sinusoidal, path along said axis. According to another variant, the anode channels may have a serpentine-shaped path.

[0045] In a variant, the anode circulation system may comprise, from upstream to downstream, from the inlet opening to the outlet opening, an anode supply channel for introducing water into the anode block, an anode chamber for exchanging water with the anode and an anode extraction channel for discharging the non-oxidized water and the dioxygen produced at the anode. The volume of the anode chamber is preferably greater than the sum of the volumes of the anode supply channel and the anode extraction channel. The anode supply channel and the anode extraction channel may open out of the anode block through the water inlet opening and through the water outlet opening.

[0046] In order to increase the contact surface between the flow of water to be oxidized and the anode and ensure a turbulent flow regime in the anode chamber, the converter preferably comprises an anode grid arranged in the anode chamber between the anode block and the anode. The anode grid is preferably electrically conductive, preferably metallic, and in contact with the anode and the anode block, to improve the extraction of electrons at the anode.

[0047] Preferably, the anode block is monolithic. Preferably, it is made of a dense material, i.e. free of porosity.

[0048] The anode block can have a general parallelepiped shape.

[0049] Preferably, the photovoltaic cell is in contact with the anode block.

[0050] Preferably, the photovoltaic cell and the anode block extend in parallel planes, and have respective faces, preferably planar, in contact with each other. In order to improve the quality of the contact between the photovoltaic cell and the anode block, the photoelectrochemical converter may comprise an anode contact sheet which is metallic, and arranged between and in contact with the face of the photovoltaic cell and the face of the anode block facing each other. The anode contact sheet is preferably flexible. It can be compressed between the photovoltaic cell and the anode block. It may have a thickness of less than 200 μm, for example approximately 100 μm. It is for example made of indium.

[0051] The anode contact foil can be compressed between the photovoltaic cell and the anode block when attaching, in particular screwing, the cover to the electrochemical module. It is then possible, by removing the cover from the electrochemical module, to easily replace the photovoltaic cell if it becomes defective.

[0052] Preferably, the anode block electrically connects the photovoltaic cell to the anode. Thus, the electrons produced at the anode by the oxidation of water flow through the anode block to reach the P layer of the photovoltaic cell.

[0053] At least a portion of the anode block may be metallic and in contact with the anode so as to electrically connect the anode to the photovoltaic cell. Preferably, the anode block is metallic, in order to ensure good electrical conduction between the anode and the photovoltaic cell and good thermal conduction of the heat accumulated by the photovoltaic cell to the water circulating in the anode fluid circulation system.

[0054] Preferably, the anode block is a stainless metal or alloy, which prevents corrosion of the anode block and limits damage to the converter. For example, it may be made of titanium. Alternatively, it is made of stainless steel and coated with a layer of gold or titanium, for example formed by vacuum plasma deposition, which has a higher electrical conductivity than stainless steel.

[0055] Furthermore, where applicable, the anode contact sheet reduces resistive bridges and promotes the conduction of positive charges between the anode and the photovoltaic cell.

[0056] Alternatively, the photovoltaic cell may be bonded to the anode block with an electrically conductive adhesive, for example an epoxy glue in which metal particles are dispersed.

[0057] Preferably, the cathode block is electrically connected, for example by a wire to the photovoltaic cell. In particular, it connects the electron-transporting N layer to the cathode so that the electrons transported by the N layer are available for the reduction taking place at the cathode, for example the formation of gaseous dihydrogen by combination of a proton H + having crossed the proton exchange membrane with an electron e" coming from the N layer.

[0058] The cathode block may extend in a plane parallel to the electrolysis cell. It may have a generally parallelepiped shape.

[0059] The cathode block may include a cathode fluid circulation system which opens onto the cathode, to at least evacuate the cathode reduction products.

[0060] The cathode fluid circulation system may comprise a cathode recess arranged opposite the cathode and which opens through at least one cathode outlet opening, for example arranged on a lateral face of the cathode block, in order to evacuate the cathode reduction product(s) from the converter.

[0061] The cathodic recess may have a textured bottom to facilitate the evacuation of cathodic reduction products.

[0062] The cathode block is preferably made of an electrically insulating material, for example a polymer, and the converter may comprise a cathode current collector, for example a metal layer, in contact with the cathode and electrically connected to the photovoltaic cell, for example by a wire and arranged, preferably compressed, between the cathode and the cathode block. The cathode current collector may be arranged in the cathode recess. The cathode block is preferably made of a polymer, which makes it possible to have a lightweight converter that can be manufactured at low cost. The cathode block may be monolithic.

[0063] The cathode current collector may be metallic, for example stainless steel. Alternatively, it comprises a polymeric support coated with a metallized layer, for example coated with gold or silver. The polymeric support is for example made of polyetheretherketone (PEEK) or glycolyzed polyethylene (PETG).

[0064] The anode may contain a catalyst for the anodic oxidation reaction, for example chosen from iridium black, iridium oxide, and mixtures thereof. The cathode may contain a catalyst for the cathodic reduction reaction, for example chosen from platinum, M0S2, a metal phosphide, in particular a nickel phosphide, and mixtures thereof. A catalyst based on such a phosphide or M0S2 can be easily activated by the higher voltages achievable, without concentration of solar radiation, with certain PIN-type photovoltaic cells, in particular of the silicon / perovskite tandem type.

[0065] In particular, the anode and / or the cathode are electrically conductive. They can be fixed, in particular glued, for example by hot pressing, on the opposite faces of the ion exchange membrane.

[0066] The anode and / or the cathode may have a porous structure, for example in the form of a foam, a woven fabric, or a non-woven fabric, impregnated with an electrically conductive binder, in particular an ink, in which the catalyst for the anodic oxidation reaction or the catalyst for the cathodic reduction reaction respectively are dispersed.

[0067] Preferably, the ion exchange membrane is a proton exchange membrane. Alternatively, the ion exchange membrane may be an anion exchange membrane.

[0068] The photovoltaic cell is preferably a tandem-type multijunction structure comprising first and second elementary PIN stacks.

[0069] The first elementary PIN stack may comprise an active layer of silicon and the second elementary PIN stack may comprise an active layer of a perovskite material. Alternatively, the first and second PIN stacks may each comprise an active layer of a perovskite material. According to other alternatives, the tandem structure is for example of the type chosen from PK / CIGS, PV / Si, OPV / OPV and III-V / Si.

[0070] In one embodiment, the anode block is the substrate on which the PIN cell layers were fabricated. The anode fluid circulation system may be formed in the anode block prior to deposition of the PIN cell layers. Preferably, a titanium layer is then disposed on the outer face of the anode block to prevent oxidation.

[0071] The invention further relates to the use of the photoelectrochemical converter according to the invention for capturing solar radiation and electrolyzing water, in particular with a view to generating dioxygen at the anode and dihydrogen at the cathode. Preferably, the solar radiation is captured without being concentrated before reaching the photovoltaic cell. Concentration of radiation is generally carried out by means of an optical system comprising a lens or a curved light reflector in order to focus the light beams towards a specific area.

[0072] Brief description of the figures

[0073] The invention may be better understood by reading the detailed description which follows, the examples presented for illustrative and non-limiting purposes, and the attached drawing in which:

[0074] [Fig. 1] is a schematic and cross-sectional view of an example of a photoelectrochemical converter according to the invention,

[0075] [Fig. 2] is an exploded and perspective view of the device illustrated in Figure 1,

[0076] [Fig. 3] is a cross-sectional view of a tandem PIN type photovoltaic cell that can be used in the device illustrated in Figure 1,

[0077] [Fig. 4] and [Fig. 5] are views along the longitudinal axis of an exemplary anode block and an exemplary cathode block respectively,

[0078] [Fig. 6] represents the electrical diagram of the first example of converter, and

[0079] [Fig. 7] represents the evolution of the electrolysis currents of the different examples of photoconverter described below.

[0080] In the figures, the constituent parts of the electrochemical converter have not necessarily been shown to scale, for the sake of clarity.

[0081] Detailed description

[0082] An exemplary embodiment of the photoelectrochemical converter 1 according to the invention is illustrated in Figures 1 and 2. It comprises an electrochemical module 2, a photovoltaic cell 3 and a cover 4.

[0083] The cover 4 comprises a frame 5, which can be fixed, for example screwed onto the electrochemical module. The frame delimits a window 6. The photovoltaic cell comprises a transparent protective plate 7 as an upper layer. Alternatively, the protective plate 7 covers the window. It thus protects the photovoltaic cell, for example from rain or hail.

[0084] The photovoltaic cell 3 has the general shape of a thin plate. It is stacked on the electrochemical module 2 so as to collect incident and unconcentrated solar radiation R Si and to transmit to the photoelectrochemical module 2 the heat that it accumulates under the effect of solar radiation. It is further electrically connected to the photoelectrochemical module. Its outer face 8 which is irradiated by solar radiation is covered by the cover 4.

[0085] The photovoltaic cell 3 is of the PIN type. In other words, it comprises at least one elementary stack formed of a hole-transporting P layer arranged opposite the electrochemical module, an active I layer and an electron-transporting N layer opposite the electrochemical module with respect to the P and I layers.

[0086] In the example illustrated in Figure 3, it is of the tandem type, that is to say that it is made up of two elementary PIN stacks arranged one on top of the other. In a variant not shown, the photovoltaic cell comprises a single elementary PIN stack.

[0087] The tandem type photovoltaic cell comprises, starting from its face irradiated by the light radiation, up to its face facing the electrochemical module: an upper electrode 9 formed of a layer of transparent conductive oxide, for example a layer of indium-tin oxide, also called ITO layer, an electron blocking layer 10, for example made of bathocuproine, known by the acronym BCP, a first PIN stack 11 comprising an N layer 12, for example made of fullerene CÔO, an active layer 1 13 made of perovskite material, for example a bromide and iodide of lead, cesium and formamidinium and a P layer 14, for example a mono-assembled layer 2-PACz, an intermediate electrode 15, for example in the form of another ITO layer, a second PIN stack comprising an N layer 16, for example made of hydrogenated amorphous silicon a-Si:H doped n with phosphorus, an active layer I 17 made of monocrystalline silicon and a layer P 18,for example made of hydrogenated amorphous silicon a-Si:H doped p with boron, the active layer I being sandwiched between layers of undoped (intrinsic) hydrogenated amorphous silicon a-Si:H, to passivate the crystalline silicon; a lower electrode 19 made for example of a bilayer comprising a PTO layer and a silver layer.,

[0088] The electrochemical module comprises an anode block 20, a cathode block 21 and an electrolysis cell 22 arranged between the anode block and the cathode block.

[0089] The electrolysis cell further comprises an anode 23 and a cathode 24 which sandwich a proton exchange membrane 25 and which are respectively in contact with the anode block and the cathode block.

[0090] The electrochemical module 2 has a generally elongated shape, for example parallelepiped, which extends in a median plane parallel to the median extension plane of the photovoltaic cell.

[0091] The lower electrode 19 of the photovoltaic cell 3 is in contact with the anode block 20.

[0092] The anode block is preferably metallic. Thus, the anode block provides an electrical connection between the anode 23 and the lower electrode 19 of the photovoltaic cell, with which it is in contact by its outer 26 and inner 27 faces respectively. The converter 1 may also comprise a metallic anode grid 28, for example made of titanium, arranged between the anode 23 and the inner face 27 of the anode block, to improve the extraction of electrons from the anode, increase the contact surface between the flow of water to be oxidized and the anode and generate turbulence which increases the heat transfer.

[0093] In a variant not shown, the anode block 20 may comprise an electrically conductive portion, for example metallic, in contact with the anode and the lower electrode and an electrically insulating portion, for example made of a ceramic or polymer material. The electrically conductive portion may surround the electrically insulating portion.

[0094] To improve the electrical contact between the anode block and the lower electrode, the photoelectrochemical converter comprises an anode contact sheet 29, for example made of indium, which is arranged between the anode block 20 and the photovoltaic cell 3. Alternatively, the anode contact sheet 29 can be replaced by a layer of an electrically conductive adhesive to bond the lower electrode to the outer face of the anode block.

[0095] The anode block 20 is shaped to supply water to the anode so that an oxidation reaction takes place at the anode to extract electrons and form protons H + Advantageously, the anode block 20 being located between the electrolysis cell 22 and the photovoltaic cell 3, the water circulating therein can be heated by the heat stored by the photovoltaic cell under the effect of the irradiation of solar radiation.

[0096] The anode block 20, illustrated in particular in FIG. 4, comprises an anode fluid circulation system 30. The fluid circulation system 30 comprises an anode inlet collecting chamber 45 and an anode outlet collecting chamber 46, and anode channels 31. The anode fluid circulation system 30 makes it possible to bring water into contact with the anode, the anode channels opening out through anode exchange openings 41 formed on the inner face 27 of the anode block.

[0097] The anode channels 31 extend parallel to each other. Each anode channel is a rectilinear groove that extends along the entire length of the anode block, from upstream to downstream, from the anode inlet collecting chamber 45 to the anode outlet collecting chamber 46. The groove may have a constant cross-section.

[0098] The converter 1 further comprises a water inlet opening 32 provided on a lateral face 33 of the anode block, and an anode introduction channel 47, the walls of which are illustrated in dotted lines in FIG. 4, which connects the water inlet opening 32 to the anode inlet collecting chamber 45.

[0099] The anode channels 31 each extend from the anode inlet collecting chamber 45. Thus, the flow of water entering the anode block through the water inlet opening is distributed in each anode channel, thus promoting a turbulent flow and exchanges with the anode. The anode block is further provided with at least one water outlet opening 34 formed on a lateral face 35 of the anode block opposite the face on which the water inlet opening 32 is formed. The anode outlet collecting chamber 46, which receives the flows of water and dioxygen resulting from the hydrolysis discharged downstream of the anode channels 31, is extended to the outlet opening 34 by an anode purge channel 48.

[0100] The fluid circulation system 30 is however not limited to that illustrated in Figures 1, 2 and 4. Other conformations of the anode channels are possible provided that they allow water circulation with a flow rate adapted to efficient oxidation of the water at the anode, rapid evacuation of the oxygen formed and preferably without bubbling, and to heating the water and cooling the PIN cell.

[0101] The cathode block 21, illustrated in particular in FIG. 5, is for example made of an electrically insulating material.

[0102] The cathode block 21 comprises a cathode fluid circulation system 36 comprising a cathode recess 37 which opens onto the cathode 24 via a cathode exchange opening 38 provided on the inner face of the cathode block and which opens out of the converter via a cathode outlet opening 39 for purging the reduction product at the cathode, for example dihydrogen. According to one example, the fluid circulation system is a cathode collection system which, apart from the cathode outlet opening 39 and the cathode exchange opening 38, is free of openings opening out of the cathode block. According to another example not illustrated, the fluid circulation system further comprises a cathode inlet opening for injecting a fluid into the cathode circulation system, for example to facilitate purging of the cathode reaction product or to transport a reactant to be reduced at the cathode.

[0103] Furthermore, a conductive wire, for example made of Pt, makes it possible to electrically connect the cathode 24 to the upper electrode 9 of the photovoltaic cell 3. The converter 1 comprises a cathode current collector 40, for example a metal or metallized grid, which is arranged in contact with the cathode in the cathode recess.

[0104] Examples

[0105] The following examples have been made.

[0106] A reversed polarity PIN silicon / perovskite tandem photovoltaic cell as shown in Figure 3 and an electrochemical module of a device as described in FR 3 127 763 A1, comprising a plastic anode block, a stainless steel cathode block and a proton exchange membrane electrolysis cell, were used. The proton exchange membrane was inserted and bonded by hot pressing between two conduction layers of porous carbon fabric impregnated with catalyst. 0.5 mg / cm 2 an ink comprising carbon and 60% by mass of platinum was applied to impregnate the cathode and 5.7 mg / cm 2 iridium black was impregnated into the anode. The active surface area of ​​the membrane is 12.25 cm 2 .

[0107] Since the components of the electrochemical module described in FR 3 127 763 A1 are designed to integrate a NIP and not a PIN type photovoltaic cell, the plastic anode block is neither electrically conductive nor heat conductive. It was therefore not possible to connect the photovoltaic cell to the anode directly through the anode block by placing the photovoltaic cell in contact with the anode block. The photovoltaic cell was therefore connected to the electrolysis cell by means of two conductive wires, as schematically illustrated in Figure 6.

[0108] In this example, the water circulating in the anode block is not heated by the heat produced by the photovoltaic cell.

[0109] The performances obtained under simulated irradiation at 1 sun and presented in Figure 7 reveal an excellent stability of the intensity of the electrolysis current i (curve C1) which is nearly 80% higher than the intensity of the electrolysis current produced by the converter described in FR 3 127 763 A1 (curve C2). The converter according to the first example has performances at least similar, or even superior, to a second example in which the converter is identical to the converter according to the first example except that it is equipped with an optimized commercial electrolysis cell (active surface 5.76 cm 2 ) coupled with a PIN solar cell (curve C3).

[0110] The results are summarized in Table 1 below. It shows the performance of PIN and NIP tandem solar cells with an illuminated area of ​​8.35 cm 2, as well as the performance of the converter according to the first and second examples and of the converter according to FR 3 127 763 AL I sc and V oc represent respectively the short-circuit current and the open-circuit voltage of the photovoltaic cells and i op and V O p represent the operating points of the converters.

[0111] [table 1]

[0112] The invention is not limited to the examples described above.

[0113] For example, the device is not limited to the production of dihydrogen. It can be adapted to the generation of carbon monoxide or formic acid from water and carbon dioxide. In particular, the cathodic fluid circulation system can be configured to bring to the cathode one or more products to be reduced. For example, the product to be reduced can be carbon dioxide in order to form, as a cathodic reduction product, formic acid, according to the principle described for example in Sato S., Arai T., Morikawa T., Uemera K., Suzuki TM, Tanaka H., Kajino T., “Selective CO2 conversion to formate conjugated with H2O oxidation utilizing semiconductor / complex hybrid photocatalysts”, J. Am. Chem. Soc., 2011, 133, p. 15240. The invention can also be used in a biological methanization unit or to produce a synthetic fuel.

[0114] Thus, the invention also relates to a method for producing methane from carbon dioxide resulting from the degradation of biological material in a methanization unit, the method comprising:

[0115] - light irradiation, in particular solar irradiation, of the photovoltaic cell of the photoelectrochemical converter according to the invention and the introduction of water into the anode circulation system of said converter to generate dihydrogen by electrolysis of the water, and

[0116] - the production of methane by reaction, in particular catalyzed, between carbon dioxide and dihydrogen.

[0117] The ion exchange membrane can be an OH' anion exchange membrane. The photoelectrochemical converter can then be implemented in a basic medium, for example containing KOH. The water is then reduced at the cathode according to the reaction 2 H2O + 2 e" — ► H2 + 2 OH" and at the cathode, the hydroxyl ions are oxidized according to the reaction 2 OH" i 02 + H2O + 2 e" .

Claims

Claims 1. Photoelectrochemical converter (1) comprising a PIN type photovoltaic cell (3) and an electrochemical module (2) fixed to the photovoltaic cell, the electrochemical module comprising an anode block (20), a cathode block (21) and an electrolysis cell (22) sandwiched between the anode block and the cathode block and which is electrically powered by the photovoltaic cell to at least oxidize water, the photoelectrochemical converter comprising a water inlet opening (32) provided on one face (33) of the anode block in order to introduce water into the converter, the electrolysis cell comprising a stack containing in succession, an anode (23), an ion exchange membrane (25) and a cathode (24),the anode block (20) being sandwiched between the electrolysis cell (25) and the photovoltaic cell (3) and comprising an anode fluid circulation system (30) comprising an anode exchange opening (31) which opens onto the anode (23) and an anode channel (30) shaped to transport the water from the water inlet opening to the anode., 2. Photoelectrochemical converter according to claim 1, the photovoltaic cell covering more than 70%, preferably more than 80%, preferably more than 90%, preferably more than 95% of the area of ​​the anode (23) and / or the cathode (24), preferably completely covering the anode and / or the cathode.

3. Photoelectrochemical converter according to any one of claims 1 and 2, the PIN type photovoltaic cell (3) being a tandem type multijunction cell comprising first and second elementary PIN stacks.

4. Converter according to the preceding claim, the first elementary PIN stack comprising an active layer of silicon and the second elementary PIN stack comprising an active layer of a perovskite material or the first and second PIN stacks each comprising an active layer of a perovskite material.

5. Converter according to any one of the preceding claims, the water inlet opening (32) being provided on a lateral face (33) of the anode block.

6. Converter according to any one of the preceding claims, the fluid circulation system extending from the water inlet opening (32) to an opening water outlet (34) provided on one face, preferably lateral and in particular opposite, of the anode block (20).

7. Converter according to any one of the preceding claims, comprising several anode channels, preferably extending parallel to each other.

8. Converter according to claims 6 and 7, the fluid circulation system comprising from upstream to downstream, from the water inlet opening to the water outlet opening, an anode inlet collecting chamber (45), the anode channels (30) and an anode outlet collecting chamber (46), each anode channel opening through its opposite ends into the anode inlet collecting chamber and into the anode outlet collecting chamber respectively.

9. Photoelectrochemical converter according to any one of the preceding claims, the cathode block being monolithic.

10. Photoelectrochemical converter according to any one of the preceding claims, the anode block electrically connecting the photovoltaic cell (3) to the anode (23).

11. Photoelectrochemical converter according to the preceding claim, the anode block comprising, preferably consisting of, a metal portion electrically connecting the anode to the photovoltaic cell.

12. Photoelectrochemical converter according to any one of the preceding claims, the converter comprising a cover (4), the photovoltaic cell (3) being entirely arranged between the cover (4) and the electrochemical module (2).

13. Photovoltaic converter according to the preceding claim, comprising an anode contact sheet (29) which is metallic, and arranged between and in contact with the face of the photovoltaic cell and the face of the anode block facing each other, the contact sheet being in particular compressed between the photovoltaic cell and the anode block.

14. Use of the photoelectrochemical converter according to any one of the preceding claims, for capturing solar radiation and electrolyzing water, the solar radiation preferably being captured without being concentrated before reaching the photovoltaic cell.

15. Process for producing methane from carbon dioxide produced by the degradation of biological material in a methanization unit, the process comprising: - the light irradiation, in particular solar, of the photovoltaic cell of the photoelectrochemical converter according to any one of claims 1 to 13, and the introduction of water into the anode circulation system of said converter to generate dihydrogen by electrolysis of the water, and - the production of methane by reaction, in particular catalyzed, between carbon dioxide and dihydrogen.

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