Low-platinum catalyst based on nitride nanoparticles and preparation method thereof

Patent metadata

Field	Value
Publication number	US-2020164350-A1
Application number	US-201916726836-A
Country	US
Kind code	A1
Filing date	Dec 25, 2019
Priority date	Jun 23, 2015
Publication date	May 28, 2020
Grant date	—

Abstract

The present invention discloses a low-platinum catalyst based on nitride nanoparticles and a preparation method thereof. A component of an active metal of the catalyst directly clades on a surface of nitride particles or a surface of nitride particles loaded on a carbon support in an ultrathin atomic layer form. Preparation steps including: preparing a transition-metal ammonia complex first, nitriding the obtained ammonia complex solid under an atmosphere of ammonia gas to obtain nitride nanoparticles; loading the nitride nanoparticles on a surface of a working electrode, depositing an active component on a surface of the nitride nanoparticles by pulsed deposition, to obtain the low platinum loading catalyst using a nitride as a substrate. The catalyst may be used as an anode or a cathode catalyst of a low temperature fuel cell, has very high catalytic activity and stability, can greatly reduce a usage amount of a precious metal in the fuel cell, and greatly reduces a cost of the fuel cell. The present invention has important characteristics of being controllable in deposition amount, simple and convenient to operate, free of protection of inert atmosphere, and etc., and is suitable for large-scale industrial production.

First claim

What is claimed is:

1 . A preparation method of a low-platinum catalyst based on nitride nanoparticles, the preparation method comprises following steps:
(1) a preparation of the nitride nanoparticles: dissolving one or more transition metal compounds in a non-aqueous solvent, then introducing ammonia gas for 0.5-1 hour, evaporating the solvent at 50-90° C. in a vacuum drying oven to obtain a transition-metal ammonia complex; high temperature nitriding the transition-metal ammonia complex in ammonia gas atmosphere for 3-5 hours to prepare transition-metal nitride nanoparticles; the transition-metal ammonia complex includes an ammonia complex formed by any one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta, or a binary or ternary ammonia complex formed by two or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta; a temperature of the high temperature nitriding is 500-900° C.; the prepared transition-metal nitride nanoparticle has a diameter of 5-15 nm; the non-aqueous solvent is an alcohol, or a mixture formed by the alcohol with a ketone or an ester; the transition metal compound comprises titanium tetrachloride, tetrabutyl titanate, chromium acetate, manganese chloride, ferric nitrate, cobaltous acetate, copper chloride, niobium chloride, molybdenum chloride or tantalum chloride; or a preparation of carbon-supported transition-metal nitride nanoparticles: except that the transition metal compound and a pretreated carbon support are added into the non-aqueous solvent simultaneously, other steps are the same as the preparation of the nitride nanoparticles; the carbon support comprises an XC-72R carbon black, a carbon nanotube, a carbon nanofiber or graphene; a loading amount of the nitride nanoparticles on the carbon support is 10 wt %-40 wt %; (2) a fabrication of a working electrode for a pulse electrodeposition, utilizing a method A or a method B as follows: the method A: weighing an appropriate amount of the nitride nanoparticles or the carbon-supported transition-metal nitride nanoparticles to add into 1-5 mL of an alcoholic solution containing an adhesive, ultrasonically dispersing to make into a slurry, using a micropipette to take an appropriate amount of the slurry to uniformly coat a surface of a working electrode substrate used, a final loading amount of a catalyst substrate material is 0.1-0.5 mg/cm2, and the working electrode for the pulse electrodeposition is obtained after drying; the adhesive comprises a polytetrafluoroethylene emulsion, a fluorocarbon resin emulsion or a perfluorosulfonate resin emulsion, a mass percent of a usage amount of the adhesive accounts for 0.5%-20% of a total amount of the catalyst substrate material based on a dry polymer resin; the alcoholic solution comprises ethanol, isopropanol or ethylene glycol; the working electrode substrate comprises a glassy carbon, a nickel foam, a titanium sheet, a platinum plated titanium sheet or a platinum sheet; and a way of the drying comprises drying by natural air-drying, radiation drying under infrared light or drying by putting into an oven; or the method B: directly adding the nitride nanoparticles or the carbon-supported transition-metal nitride nanoparticles that are used as the substrate material into a cathode electrolyte solution containing a required active metal for the pulse electrodeposition, stirring, forming the working electrode by a continuous contact of the particles with a cathode conductor; and a catholyte and an anolyte are isolated using a microporous medium; and (3) the pulse electrodeposition: placing the fabricated working electrode into 0.1-0.5 M H 2 SO 4 solution saturated with nitrogen, scanning from an open-circuit voltage to −0.25-0 V at a scan speed of 5-50 mV/s, with a number of scanning laps of 10-50 laps, achieving cleanness and an activating treatment of the substrate material; then transferring the electrode into a nitrogen saturated electrodepositing solution containing a salt of the required active metal, a complexing agent and a conductive aid under an atmosphere of nitrogen, connecting an auxiliary electrode with a reference electrode; setting a pulse frequency, a number of times of pulse deposition, a conduction time and a disconnection time, then opening a pulse electrodeposition program, washing the catalyst out from the surface of the electrode when the electrodeposition is completed to obtain the low-platinum catalyst based on the nitride nanoparticles.

2 . The preparation method of the low-platinum catalyst based on the nitride nanoparticles according to claim 1 , wherein a pretreatment of the carbon support is as follows: weighing 5-20 g of the carbon support, adding into a 200-1000 mL beaker, injecting acetone of 3/5 volume of the beaker, stirring at room temperature for 2-12 hours, filtering, washing, then vacuum drying at 50-80° C.; calcining the dried carbon support at 200-500° C. under an atmosphere of high purity argon for 2-3 hours, then heating and refluxing in a mixed solution of HNO 3 and H 2 SO 4 with a molar ratio of 1:1-1:5 for 6-10 hours, keeping a temperature at 70-80° C., the mixed solution having a concentration of 2-5 mol/L, after finally filtering the carbon support and washing the carbon support to neutral with double-distilled water, vacuum drying in the oven at 50-90° C. for 8-24 hours to obtain the pretreated carbon support.

3 . A low-platinum catalyst based on nitride nanoparticles, comprising:
an active component, wherein the active component of the catalyst is transition-metal nitride nanoparticles with an atomic layer cladding of an active metal, the active metal cladding on a surface of a transition metal nitride served as a substrate or of transition-metal nitride nanoparticles supported on a carbon support in an ultrathin atomic layer form; wherein the transition metal nitride served as the substrate or the transition metal nitride supported on the carbon support comprises a unary, a binary or a ternary transition metal nitride, an average particle size of the nanoparticles being 5-15 nm; and a mass composition of the catalyst is as follows: the carbon support is 50%-80%, the transition metal nitride is 10%-40%, and a component of the active metal is 4%-10%, wherein the low-platinum catalyst based on nitride nanoparticles is prepared by the following steps:
(1) a preparation of the nitride nanoparticles: dissolving one or more transition metal compounds in a non-aqueous solvent, then introducing ammonia gas for 0.5-1 hour, evaporating the solvent at 50-90° C. in a vacuum drying oven to obtain a transition-metal ammonia complex; high temperature nitriding the transition-metal ammonia complex in ammonia gas atmosphere for 3-5 hours to prepare transition-metal nitride nanoparticles; the transition-metal ammonia complex includes an ammonia complex formed by any one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta, or a binary or ternary ammonia complex formed by two or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta; a temperature of the high temperature nitriding is 500-900° C.; the prepared transition-metal nitride nanoparticle has a diameter of 5-15 nm; the non-aqueous solvent is an alcohol, or a mixture formed by the alcohol with a ketone or an ester; the transition metal compound comprises titanium tetrachloride, tetrabutyl titanate, chromium acetate, manganese chloride, ferric nitrate, cobaltous acetate, copper chloride, niobium chloride, molybdenum chloride or tantalum chloride; or
a preparation of carbon-supported transition-metal nitride nanoparticles: except that the transition metal compound and a pretreated carbon support are added into the non-aqueous solvent simultaneously, other steps are the same as the preparation of the nitride nanoparticles; the carbon support comprises an XC-72R carbon black, a carbon nanotube, a carbon nanofiber or graphene; a loading amount of the nitride nanoparticles on the

Assignees

• Univ South China Tech

Inventors

• Liao Shijun
• Tian Xinlong
• Luo Junming
• Chen Rong

Classifications

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• H01M4/926

  on carbon or graphite · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• B01J23/42

  Platinum · CPC title

• H01M4/8853 Primary

  Electrodeposition · CPC title