Abstract: The present particles, compositions and methods are Nb-oxide embedded carbon based electrocatalysts. In one embodiment, a carbon based support particle is provided having NbOx (0 ?x?2 is average value of amorphous low-oxidation-state niobium oxides) and a catalytically active metal deposited thereupon. In one embodiment, a method is provided of embedding niobium oxides into pores of carbon black, which involves filling about 4 nm pores on Ketjenblack EC 600JD (KB) with Nb(V) ethoxide by sonication, and decomposing/reducing dried Nb(V) precursor in carbon to ?5 nm particles of NbOx. The embedded, small metal or metal oxide particles over porous carbon surface may find applications in fuel cell and battery technologies. The present compositions can be used for fabricating active and durable catalysts for oxygen reduction reaction (ORR).

Abstract: The present disclosure relates to methods for producing nanoparticles. The nanoparticles may be made using ethanol as the solvent and the reductant to fabricate noble-metal nanoparticles with a narrow particle size distributions, and to coat a thin metal shell on other metal cores. With or without carbon supports, particle size is controlled by fine-tuning the reduction power of ethanol, by adjusting the temperature, and by adding an alkaline solution during syntheses. The thickness of the added or coated metal shell can be varied easily from sub-monolayer to multiple layers in a seed-mediated growth process. The entire synthesis of designed core-shell catalysts can be completed using metal salts as the precursors with more than 98% yield; and, substantially no cleaning processes are necessary apart from simple rinsing. Accordingly, this method is considered to be a “green” chemistry method.

Abstract: A method of depositing contiguous, conformal submonolayer-to-multilayer thin films with atomic-level control is described. The process involves electrochemically exchanging a mediating element on a substrate with a noble metal film by alternatingly sweeping potential in forward and reverse directions for a predetermined number of times in an electrochemical cell. By cycling the applied voltage between the bulk deposition potential for the mediating element and the material to be deposited, repeated desorption/adsorption of the mediating element during each potential cycle can be used to precisely control film growth on a layer-by-layer basis.

Abstract: The present invention is to provide a method for producing a core-shell catalyst for fuel cells, which is configured to facilitate shell deposition by, at the time of shell deposition, decreasing an oxidation-reduction potential lower than ever before. Disclosed is a method for producing a core-shell catalyst for fuel cells, wherein the method comprises: a bubbling step of bubbling hydrogen into a mixture A containing a core fine particle-supported carbon and alcohol; a first refluxing step of refluxing the mixture A after the bubbling step; a mixing step of preparing a mixture B by, after the first refluxing step, mixing the mixture A having a temperature that is lower than that in the first refluxing step with a shell material; and a second refluxing step of refluxing the mixture B.

Abstract: The present invention is to provide a method for producing a core-shell catalyst for fuel cells, which is configured to facilitate shell deposition by, in the production of the core-shell catalyst for fuel cells, decreasing an oxidation-reduction potential applied for shell deposition lower than ever before. Disclosed is a method for producing a core-shell catalyst for fuel cells, wherein the method comprises: a first refluxing step of refluxing a mixture A containing a core fine particle-supported carbon, alcohol and water; a mixing step of preparing a mixture B by, after the first refluxing step, mixing the mixture A having a temperature that is lower than that in the first refluxing step with a shell material; and a second refluxing step of refluxing the mixture B.

Abstract: The present disclosure relates to methods for producing nanoparticles. The nanoparticles may be made using ethanol as the solvent and the reductant to fabricate noble-metal nanoparticles with a narrow particle size distributions, and to coat a thin metal shell on other metal cores. With or without carbon supports, particle size is controlled by fine-tuning the reduction power of ethanol, by adjusting the temperature, and by adding an alkaline solution during syntheses. The thickness of the added or coated metal shell can be varied easily from sub-monolayer to multiple layers in a seed-mediated growth process. The entire synthesis of designed core-shell catalysts can be completed using metal salts as the precursors with more than 98% yield; and, substantially no cleaning processes are necessary apart from simple rinsing. Accordingly, this method is considered to be a “green” chemistry method.

Abstract: Highly effective, standalone gas-diffusion electrodes (GDEs) and the methods for their manufacture and test are disclosed, Nanocataiysis are directly bonded on a gas diffusion layer, so that the integrity of the catalyst layer holds without polymer electrolyte membrane, facilitating minimization of electronic, prottmtc, and diffusion resistances in the catalyst layer. The devised embodiments provide examples showing a facile hanging-strip method for testing the standalone GDEs in a solution electrochemical cell, which removes the mA-cm?2-scale mass transport limited currents on rotating disk electrodes to allow studies of reaction kinetics on single electrode over sufficiently wide current ranges (up to A cm?2) without mass transport limitation. Ultralow-Pi-content GDEs are fabricated as the cathode for hydrogen evolution in water eiectrolyzers and as the anode for hydrogen oxidation in hydrogen fuel cells.

Abstract: A method of depositing contiguous, conformal submonolayer-to-multilayer thin films with atomic-level control is described. The process involves electrochemically exchanging a mediating element on a substrate with a noble metal film by alternatingly sweeping potential in forward and reverse directions for a predetermined number of times in an electrochemical cell. By cycling the applied voltage between the bulk deposition potential for the mediating element and the material to be deposited, repeated desorption/adsorption of the mediating element during each potential cycle can be used to precisely control film growth on a layer-by-layer basis.

Abstract: A method of depositing contiguous, conformal submonolayer-to-multilayer thin films with atomic-level control is described. The process involves the use of underpotential deposition of a first element to mediate the growth of a second material by overpotential deposition. Deposition occurs between a potential positive to the bulk deposition potential for the mediating element where a full monolayer of mediating element forms, and a potential which is less than, or only slightly greater than, the bulk deposition potential of the material to be deposited. By cycling the applied voltage between the bulk deposition potential for the mediating element and the material to be deposited, repeated desorption/adsorption of the mediating element during each potential cycle can be used to precisely control film growth on a layer-by-layer basis. This process is especially suitable for the formation of a catalytically active layer on core-shell particles for use in energy conversion devices such as fuel cells.

Abstract: The present disclosure relates to methods for producing nanoparticles. The nanoparticles may be made using ethanol as the solvent and the reductant to fabricate noble-metal nanoparticles with a narrow particle size distributions, and to coat a thin metal shell on other metal cores. With or without carbon supports, particle size is controlled by fine-tuning the reduction power of ethanol, by adjusting the temperature, and by adding an alkaline solution during syntheses. The thickness of the added or coated metal shell can be varied easily from sub-monolayer to multiple layers in a seed-mediated growth process. The entire synthesis of designed core-shell catalysts can be completed using metal salts as the precursors with more than 98% yield; and, substantially no cleaning processes are necessary apart from simple rinsing. Accordingly, this method is considered to be a “green” chemistry method.

Abstract: Hollow metal nanoparticles and methods for their manufacture are disclosed. In one embodiment the metal nanoparticles have a continuous and nonporous shell with a hollow core which induces surface smoothening and lattice contraction of the shell. In a particular embodiment, the hollow nanoparticles have an external diameter of less than 20 nm, a wall thickness of between 1 nm and 3 nm or, alternatively, a wall thickness of between 4 and 12 atomic layers. In another embodiment, the hollow nanoparticles are fabricated by a process in which a sacrificial core is coated with an ultrathin shell layer that encapsulates the entire core. Removal of the core produces contraction of the shell about the hollow interior. In a particular embodiment the shell is formed by galvanic displacement of core surface atoms while remaining core removal is accomplished by dissolution in acid solution or in an electrolyte during potential cycling between upper and lower applied potentials.

Abstract: A method of depositing contiguous, conformal submonolayer-to-multilayer thin films with atomic-level control is described. The process involves the use of underpotential deposition of a first element to mediate the growth of a second material by overpotential deposition. Deposition occurs between a potential positive to the bulk deposition potential for the mediating element where a full monolayer of mediating element forms, and a potential which is less than, or only slightly greater than, the bulk deposition potential of the material to be deposited. By cycling the applied voltage between the bulk deposition potential for the mediating element and the material to be deposited, repeated desorption/adsorption of the mediating element during each potential cycle can be used to precisely control film growth on a layer-by-layer basis. This process is especially suitable for the formation of a catalytically active layer on core-shell particles for use in energy conversion devices such as fuel cells.