37 results about "Underpotential deposition" patented technology

High-surface-area carbon nanostructures coated with a smooth and conformal submonolayer-to-multilayer thin metal films and their method of manufacture are described. The preferred manufacturing process involves the initial oxidation of the carbon nanostructures followed by immersion in a solution with the desired pH to create negative surface dipoles. The nanostructures are subsequently immersed in an alkaline solution containing non-noble metal ions which adsorb at surface reaction sites. The metal ions are then reduced via chemical or electrical means and the nanostructures are exposed to a solution containing a salt of one or more noble metals which replace adsorbed non-noble surface metal atoms by galvanic displacement. Subsequent film growth may be performed via the initial quasi-underpotential deposition of a non-noble metal followed by immersion in a solution comprising a more noble metal. The resulting coated nanostructures may be used, for example, as high-performance electrodes in supercapacitors, batteries, or other electric storage devices.

The invention discloses a core-shell structure catalyst for fuel cells and its pulse electrodeposition preparation method. The active component of the catalyst is a nanoparticle with a core-shell structure, and an active metal is cladded in the form of an ultrathin shell on the surface of a carbon carrier loaded metal or alloy nanoparticle serving as a core. The catalyst takes a non-platinum noble metal or transition metal as the core, and adopts more than one of Pt, Ir or Au as the shell. The preparation method includes: preparation of the nanoparticle serving as the core, making of a working electrode for pulse electrodeposition, and preparation of the catalyst by pulse electrodeposition. The catalyst can be used as an anode or cathode catalyst of a low temperature fuel cell. The obtained catalyst has very high stability. Compared with underpotential deposition, the method is simple to operate, has no need for inert atmosphere protection, and is more suitable for large-scale industrial production, also can greatly reduce the noble metal consumption of fuel cells, and greatly reduce the cost of fuel cells, thus having great significance in promoting the commercialization process of fuel cells.

Transition metal nanostructures coated with a contiguous, conformal submonolayer-to-multilayer noble metal film and their method of manufacture are described. The manufacturing process involves the initial formation of suitably sized transition metal or alloy nanostructures which may be nanorods, nanobars, or nanowires. A monolayer of a non-noble metal is deposited onto the surface of the nanostructures by underpotential deposition. This is followed by the galvanic displacement of the non-noble metal by a second metal to yield a conformal coating of a monolayer of the second metal on the surface of the nanostructures. The replacement of atoms of the first metal by atoms of the second metal is an irreversible and spontaneous redox reaction which involves the replacement of a non noble metal by a more noble metal. The process can be controlled and repeated to obtain the desired film coverage. The resulting coated nanostructures provide heightened catalytic activity and can be used as high-performance electrodes in fuel cells.

The invention provides a preparation method of a carbon-supported nano platinum alloy catalyst. The method comprises the following steps: I. depositing Cu on the surfaces of Pt/C carbon-supported nano platinum catalyst particles by utilizing an underpotential deposition method to obtain Cu-Pt/C; II. dispersing Cu-Pt/C in a solution containing 3d transition metal ions uniformly to obtain Cu-Pt/C suspension, and drying the Cu-Pt/C suspension to obtain a dried sample; III. ball-milling the dried sample, and putting the dried sample in a reducing atmosphere to be reduced and alloyed; IV. dealloying the sample obtained in the step III, and washing and drying to obtain the carbon-supported nano alloy catalyst. The preparation method provided by the invention has the beneficial effects that the losses caused because carbon support materials undergo high temperature can be effectively reduced, thus relieving the problem of severe fused growth of carbon-supported Pt alloy nanoparticles at high temperature; the nano platinum alloy catalyst prepared by the method has the advantages of small platinum alloy particle size, good dispersibility and high catalytic oxygen reduction property.

The invention discloses a preparation method of a core-shell-structured catalyst for a fuel cell, and the catalyst takes copper-modified platinum, palladium and the like as a shell and takes noble metals such as palladium and gold as a core. Specifically, the method comprises the following steps: by taking noble metals such as palladium and gold as a substrate, performing reaction in a mixed electrolyte prepared from a precursor containing platinum and copper or a precursor solution of palladium and copper and citric acid; and by utilizing the properties that copper realizes selective preferential deposition on the surfaces of the noble metals in an underpotential deposition range and replacement reaction between copper and platinum or between copper and palladium can be realized, preparing a copper-modified platinum shell or palladium shell, thereby obtaining the core-shell-structured catalyst taking palladium or gold as the core. The method disclosed by the invention is friendly to the environment and controllable in load; the activity and stability of the catalyst to oxygen reduction reaction are superior to those of a commercialized platinum-carbon catalyst; and when the electrode constructed based on the catalyst is used for the fuel cell, the properties of the fuel cell and the utilization ratio of Pt can be enhanced, and the cost of the fuel cell can be lowered.

The invention provides a nanotube with a coaxial heterojunction structure of an ordered array and a preparation method for a nanotube array film with the coaxial heterojunction structure. A surface is formed by an under potential sedimentation process to chemically limit growth and the epitaxial growth is realized from the angle of a monoatomic layer. An epitaxial sensibilization heterogeneous phase is uniformly covered on the tube wall of the TiO2 nanotube to form the coaxial heterojunction structure together with the nanotube array so as to avoid the phenomenon that an epitaxial sensibilization layer blocks the nanotube. The coaxial heterojunction structure cannot reduce specific surface area and adsorbability of the TiO2 nanotube array, is beneficial to improve the contact area of a sensitizing agent and the TiO2 surface and can effectively improve the visible light response performance of the TiO2 nanotube ordered array. The photoelectric conversion efficiency of the CdS/TiO2 coaxial heterojunction nanotube array prepared by the method reaches 8.13 percent under the full spectrum simulated sun illumination. The CdS/TiO2 coaxial heterojunction nanotube array can be widely applied to the fields of photochemical catalysis, solar cell, gas sensing, biomedicine and the like.

The invention discloses a method for directly preparing a catalytic layer of a platinum monoatomic layer used for a proton exchange membrane fuel cell. The method comprises the following steps of directly preparing a Pd/C catalytic layer in advance by using the catalytic layer through electrospinning technique, selecting polymer such as polyacrylic acid as a binder, afterwards, in a three-electrode system, adopting an underpotential deposition method to deposit Cu of a monoatomic layer on the Pd/C catalytic layer, then performing replacement to obtain the Pt of the monoatomic layer, and finally preparing a Pd/C@PtML catalytic layer. The Pd/C@PtML catalytic layer serves as a cathode, the Pd loading is 0.15mg/cm<-2>, the Pt loading is 0.02mg/cm<-2>, the maximum power density of a single cellis 560mW/cm<-2> (H2-Air), so that the Pd/C@PtML catalytic layer is superior to a catalytic layer of which the cathode Pt loading is 0.09mg/cm<-2>. By carrying out single cell acceleration attenuationtests on two catalytic layers, the Pd/C@PtML catalytic layer can be found to have better stability.

Disclosed is a method for producing a fine catalyst particle comprising a palladium-containing particle and a platinum outermost layer covering the palladium-containing particle, wherein a first composite body containing palladium and platinum is formed by mixing the palladium-containing particle with a first solution in which a platinum compound is dissolved, and then covering at least part of a surface of the palladium-containing particle with platinum; wherein a second composite body containing palladium, platinum and copper is formed by mixing the first composite body with a second solution in which a copper compound is dissolved, and then covering at least part of a surface of the first composite body with copper using copper underpotential deposition; and wherein the copper in the second composite body is substituted with platinum derived from a third solution in which a platinum compound is dissolved.

The invention provides a nickel-bismuth hybridized nanowire and a preparation method thereof. The hybridized nanowire consists of nickel and bismuth, and has the diameter of 75 nanometers and the length of not more than 100 mu m. The method comprises the following steps of: preparing an alumina template with the pore diameter of between 15 and 200 nanometers by using an oxidized aluminum sheet; evaporating a gold film on the bottom surface of the alumina template with a through hole so as to obtain the alumina template on which the gold film is evaporated; putting the alumina template on which the gold film is evaporated into mixed electroplating liquid of the nickel and the bismuth for performing underpotential deposition so as to obtain the hybridized nanowire which is generated in the through hole of the alumina template and consists of the nickel and the bismuth; and putting the alumina template of which the through hole is provided with the hybridized nanowire into alkaline solution for corroding the alumina template so as to obtain the nanowire which consists of the nickel and the bismuth. A functional hybridized nanowire which consists of magnetic metal nickel and semimetalbismuth has great potential application to magnetically-controlled photoelectric combined thermoelectric nano-devices.

The present invention discloses a method for preparing a stepped Pt-Au core-shell structural catalyst, and the stepped single atomic shell Pt-Au core-shell structural catalyst can be prepared by two-step underpotential deposition and two-step nonuniformity chemical in-situ displacement. Compared with a Pt-Au alloy structure catalyst, the Pt utilization rate can be effectively improved by single Pt; compared with a conventional single-layer core-shell structure Pt catalyst, by the stepped surface structure, each Pt atom is adjacent to Au atoms, Au can play electronic effects; and Pt sites are blocked by the Au atoms, Au can also play the overall effect; compared with a conventional sub-monolayer shell structure Pt catalyst, the complete Pt layer surface structure can improve the stability of the catalyst. The method not only can achieve a high Pt shell atom utilization rate, and reduces toxic intermediate products, and the catalytic reaction is performed towards the most favorable path.

The invention provides a catalyst with ultra-low platinum content for a fuel cell and a preparation method thereof. After heat treatment of a metal source and oleylamine and trioctylphosphine, a noblemetal salt is added dropwise and dried to form spherical nanoparticles, The nano-particles containing organic phase are loaded on the surface of graphite electrode and the organic phase is removed simultaneously by vacuum pre-sintering reduction. During the electrochemical treatment, copper is deposited on the surface of graphite electrode to form a monoatomic layer of copper. At last, platinum is replaced by potassium chloroplatinate to form a multilayered core-shell structure of transition metal-precious metal-platinum and finally the required catalyst is prepared by carbon loading. A monoatomic layer formed by underpotential deposition of copper is replaced by platinum, The thickness of the platinum layer can be controlled effectively, and the catalytic active sites on the surface of the platinum layer are not affected, so that the catalytic performance is guaranteed, the manufacturing cost of the catalyst is reduced, and the defects that the thickness of the platinum layer and thereduction of the surface active sites are difficult to be controlled by the catalyst with low platinum loading capacity are overcome.

The invention discloses a preparation method of a graphene and two-dimensional noble metal cluster composite material, comprising following steps: oxidizing graphite in a solution to form graphite oxide, ultrasonically dispersing the graphite oxide in an aqueous solution to form a graphite oxide solution, and dropping the solution to the surface of a glass electrode before natural slow drying; dipping the glass electrode in a mixed solution containing ions of a mediate metal M (Pb or Cu) and noble metal ions, subjecting the glass electrode to underpotential deposition and dissolution and stripping in a certain potential interval, after multiple volt-ampere cycles, depositing a noble metal on the surface of a graphene layer in a two-dimensional cluster form, and forming the graphene and two-dimensional noble metal cluster composite material. The graphene and two-dimensional Pt/Ru cluster composite material prepared by the method has super-high catalytic activity for methanol oxidation reaction. The invention is expected to enrich the preparation methods of graphene composite materials, optimize their structure, improving their performance, and widen their applicable ranges.

The invention discloses a bipyramid structure gold nanoparticle and a preparation method thereof. The gold nanoparticle is characterized in that the gold nanoparticle is in a pentagonal concave-surface curve-edge bipyramid structure; the surface of the gold nanoparticle is in an inner sunken shape; and the edge of the gold nanoparticle is wavy. By taking a gold bipyramid as a template, and a chloroauric acid solution and a silver nitrate solution as metal precursors, reduction deposition of gold elements in different parts of the surface of the bipyramid is adjusted by a regrowth method, and the gold nanoparticle in a concave-surface curve-edge bipyramid shape is obtained. According to the gold nanoparticle in the pentagonal concave-surface curve-edge bipyramid structure, through the underpotential deposition principle, gold atoms mainly and selectively grow at the edges of the bipyramid template; in addition, the surfaces of the bipyramid gradually grow in the transverse and axial directions. The gold nanoparticle in the pentagonal concave-surface curve-edge bipyramid structure has excellent optical properties, and the plasma resonance wavelength of the surface of the gold nanoparticle can be adjusted.

The invention discloses a mixing device for a potassium-based battery and a supercapacitor and a preparation method thereof. The method includes the following steps: preparing a negative electrode: namely a step of mixing and dissolving a negative electrode carbon material with carbon black and CMC in a certain weight ratio in a mixed solution of water and ethanol, stirring uniformly and then applying slurry to current collector copper foil, and performing annealing treatment in a vacuum environment at 60 DEG C-90 DEG C for 15-20 h; preparation a positive electrode: namely a step of mixing anddissolving a positive electrode carbon material with the carbon black and PVDF in a certain weight ratio in NMP, stirring uniformly and then applying the slurry to current collector aluminum foil, and performing the annealing treatment in a vacuum atmosphere at 60 DEG C-90 DEG C for 15-20 h; and preparing an electrolyte: namely a step of allowing the electrolyte to be a potassium-based salt electrolyte, and enabling positive ions in the electrolyte to be embedded in the negative electrode carbon material when the negative electrode is charged, and to be removed from the negative electrode carbon material during discharging; and enabling negative ions in the electrolyte to perform underpotential deposition when the positive electrode is charged, and enabling the negative ions to be adsorbed in the positive electrode carbon material and to be desorbed from the positive electrode carbon material during discharging.

The invention relates to a modification method of a Pd membrane electrode based on formic acid electrooxidation. The modification method comprises the steps of carrying out underpotential deposition on the surface of Pd by utilizing Sb, depositing a single layer of Sb on the surface of a Pd substrate so as to improve a Pd surface structure, polishing a glassy carbon electrode on a piece of chamois leather to form a mirror surface, then carrying out electrochemical cleaning in 0.1M of HClO4 by adopting a cyclic voltammetry, depositing the Pd in a Pd plating solution, then carrying out controlled potential electrodeposition (0.2-0.3Vvs.SEC) in 0.1mM of antimony potassium tartrate (APT)+0.5M of H2SO4 for 10-30s, and depositing the single layer of Sb on the surface of the Pd substrate. Compared with the prior art, with the adoption of the modification method, the single layer of Sb is deposited on the surface of the Pd substrate by virtue of a simple UPD (Under Potential Deposition) technology, and the Pd electrode modified by the Sb has the relatively good catalytic effect on formic acid.

The invention belongs to the field of electro-catalysis, and relates to a monatomic metal-molybdenum sulfide nano-composite as well as a preparation method and an application thereof. The preparation method comprises the following specific steps: modifying the surface of a glassy carbon electrode with a molybdenum sulfide suspension, carrying out underpotential deposition in an inert gas saturated copper sulfate precursor solution, and then transferring into an inert gas saturated potassium chloroplatinite solution to carry out chemical replacement, thereby obtaining the monatomic platinum-molybdenum sulfide nanocomposite. In addition, the invention provides other metal monatomic (palladium, lead, tin and bismuth)-molybdenum sulfide nano-composites prepared by adopting the preparation method. In addition, compared with a commercial platinum/carbon catalyst, the monatomic platinum-molybdenum sulfide nano-composite is higher in hydrogen precipitation catalysis reaction activity, and the preparation method disclosed by the invention is normal in temperature and pressure, controllable in operation, simple and easy to implement, and can be widely applied to various heterogeneous catalysis reactions.

A method of performing electroless electrochemical atomic layer deposition is provided and includes the steps: providing a substrate including an exposed upper metal layer; exposing the substrate to afirst precursor solution to create a sacrificial metal monolayer on the exposed upper metal layer via underpotential deposition, where the first precursor solution is an aqueous solution including areducing agent; subsequent to the forming of the sacrificial metal monolayer, rinsing the substrate; subsequent to the rinsing of the substrate, exposing the substrate to a second precursor solution to replace the sacrificial metal monolayer with a first deposition layer; and subsequent to replacing the sacrificial metal monolayer with the first deposition layer, rinsing the substrate. The exposure of the substrate to the first precursor solution and the exposure of the substrate to the second precursor solution are electroless processes.

The invention discloses a treatment method of a silver electrode for ion chromatography ampere detection, and relates to the technical field of electrochemical detection. According to the treatment method of the silver electrode for the ion chromatography ampere detection which is provided in the invention, firstly, waterproof abrasive paper with different mesh numbers is adopted for polishing; anultra-thin sensitization copper layer is obtained on the polished silver electrode through underpotential deposition; then, an electroless deposition technology is used for further inducing formationand growth of silver crystals on the obtained ultrathin sensitization copper layer; and the surface of the treated silver electrode has a fine crystal structure of nanometer or submicron silver particles. According to the method, the apparent area of the silver electrode after mechanical polishing treatment is reduced; in order to solve the technical problems, the technical effects of increasingthe effective area of the surface of the silver electrode and enhancing the electrochemical activity of the silver electrode are achieved; and, in addition, the ultrathin sensitization copper layer provided by the invention is prepared from a high-concentration Cu(NO<3>)<2> solution, has the advantages of being stable and cleanable, and has a remarkable effect of inducing electroless silver deposition.