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

Patent metadata

Field	Value
Publication number	US-11524280-B2
Application number	US-201916726836-A
Country	US
Kind code	B2
Filing date	Dec 25, 2019
Priority date	Jun 23, 2015
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

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 low-platinum catalyst based on transition-metal 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, and the active metal cladding on a surface of a transition metal nitride serves as a substrate in an ultrathin atomic layer form; wherein the transition metal nitride serves as the substrate and 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 transition metal nitride is 10%-40%, and a component of the active metal is 4%-10%,
wherein the low-platinum catalyst based on transition-metal nitride nanoparticles is prepared by the following steps:
(1) a preparation of the transition-metal 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;
(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 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 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 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 transition-metal nitride nanoparticles,
wherein the ultrathin atomic layer is composed of 1-5 atomic layers.

2. The low-platinum catalyst according to claim 1 , wherein the transition metal nitride comprises one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta, or the transition metal nitride comprises binary and ternary transition metal nitrides consisting of two or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta.

3. The low-platinum catalyst according to claim 1 , wherein a specific preparation process of the transition-metal ammonia complex of the step (1) is as follows: adding a transition metal precursor into a beaker containing the non-aqueous solvent, transferring into a Meng washing bottle after dissolving of the transition metal precursor is completed, introducing ammonia gas for complexation, with a gas flow of ammonia gas being controlled as 30-100 ml/min, and an introducing time of 0.5-1 hour; transferring an obtained mixture containing a complex into a crucible, vacuum drying in the oven at 50-90° C. for 8-24 hours to obtain the transition-metal ammonia complex; wherein the transition metal precursor comprises one or two or three of titanium tetrachloride, tetrabutyl titanate, cobaltous acetate, ferric nitrate, copper chloride, chromium acetate, manganese chloride, niobium chloride, molybdenum chloride or tantalum chloride; and a concentration range of the transition metal precursor in a reaction system solution is 0.1-3 mg/mL.

4. The low-platinum catalyst according to claim 3 , wherein the transition metal nitride comprises one of Ti, V, Cr, Mn, Fe, Co, Ni Cu, Nb, Mo or Ta, or the transition metal nitride comprises binary and ternary transition metal nitrides consisting of two or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta.

5. The low-platinum catalyst according to claim 1 , wherein in the step (3), the active metal comprises one or more of Pt, Au, Pd, Ru and Ir; a salt of the active metal comprises one or more of tetraammineplatinum chloride monohydrate, chloroplatinic acid, chloroauric acid, palladium dichloride, ruthenium trichloride and iridous chloride; the complexing agent comprises citric acid, EDTA or polyvinylpyrrolidone; the conductive aid is sodium sulfate or potassium sulfate; and a concentration of a component of the active metal in the electrodepositing solution is 5-100 mM.

6. The low-platinum catalyst according to claim 5 , wherein the transition metal nitride comprises one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta, or the transition metal nitride comprises binary and ternary transition metal nitrides consisting of two or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo or Ta.

7. The low-platinum catalyst according to claim 1 , wherein a way of deposition of the active metal adopted in the step (3) is the pulse electrodeposition, the pulse frequency is 100-10000 s −1 , each pulse contains a turn-on time and a turn-off time, the turn-on time (t on ) is 0.00003 s to 0.001 s, the turn-off time (t off ) is 0.00015-0.01 s, a ratio of the turn-on time to the turn-off time (t on /t off ) varies depending on a molar concentration of the active metal in an electrolyte and the loading amount of the active metal required, with a value between 0.1 and 100; and a total pulse nu

Assignees

• Univ South China Tech

Inventors

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

Classifications

• B01J23/42

  Platinum · CPC title

• B82Y30/00

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

• H01M4/8853 Primary

  Electrodeposition · CPC title

• H01M4/926

  on carbon or graphite · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title