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

Patent metadata

Field	Value
Publication number	US-2018185825-A1
Application number	US-201515739755-A
Country	US
Kind code	A1
Filing date	Dec 30, 2015
Priority date	Jun 23, 2015
Publication date	Jul 5, 2018
Grant date	—

Abstract

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.

First claim

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 alcohols, or a mixture formed by the alcohols 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 and tantalum chloride; and 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; and 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 H2SO4 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 ⅗ 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 . The preparation method of the low-platinum catalyst based on the nitride nanoparticles 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 a nitride ammonia complex; wherein the precursor comprises one or two or three of titanium tetrachloride, iron acetate, cobalt acetate, nickel acetate, vanadium chloride, chromic acetate, manganese chloride and niobium chloride; and a concentration range of the precursor in a reaction system solution is 0.1-3 mg/mL

4 . The preparation method of the low-platinum catalyst based on the nitride nanoparticles 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.

5 . The preparation method of the low-platinum catalyst based on the nitride nanoparticles 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/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 number is 500-20000.

6 . The preparation method of the low-platinum catalyst based on the nitride nanoparticles according to claim 1 , wherein a pulse current density of the pulse electrodeposition in the step (3

Assignees

• Univ South China Tech

Inventors

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

Classifications

• H01M4/8853 Primary

  Electrodeposition · CPC title

• B01J27/24 Primary

  Nitrogen compounds · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• B01J37/0072

  Preparation of particles, e.g. dispersion of droplets in an oil bath · CPC title

• H01M4/926

  on carbon or graphite · CPC title