碳化钨制备中升温速率对Pt-WC/C电氧化甲醇催化性能的研究

Study on the effect of heating rate in the preparation of tungsten carbide for Mathonal Electrooxidation by Pt-WC/C

本文采用程控升温还原法(TPR)制备了碳化钨颗粒,然后使用EG+NaBH4作为还原剂制备了Pt-WC/C催化剂,详细地研究了碳化过程中升温速率对碳化钨样品的形貌以及Pt-WC/C对电氧化甲醇催化性能的影响。XRD分析结果表明所有获得的样品均为WC,是多晶的六方结构,且改变碳化过程中升温速率不仅直接影响到样品表面形貌,而且影响WC物理化学性质。当以1.7K/min的升温速率制备获得的碳化钨颗粒的其分散性和表面孔结构均优于文献中常用的1.0K/min所制备的样品,且由其进一步制备成的Pt-WC/C催化剂颗粒对甲醇的电催化氧化的比质量活性比以1.0K/min所制备获得的Pt-WC/C催化剂的比质量活性(500mA/mg-Pt)提高了17%,达到584mA/mg-Pt。而以3.3 K/min所制备的碳化钨所合成的Pt-WC/C催化剂比质量活性为仅390 mA/mg-Pt。

Temperature programming reduction（TPR）method was used to synthesize tungsten carbide particles where Pt particles were reduced by the mixture of sodium borohydride（NaBH4）and ethylene glycol as a reductant to form Pt-WC/C particles.Studies were carefully carried out both on the effect of heating rate in the preparation of tungsten carbide to affect the surface topography and on the effect of the catalytic acivity of Mathanol electro-oxidation by Pt-WC/C.Analysis from Scanning electron microscope（SEM）indicated that the samples＇ surface morphology were directly effected by the different heating rate during the carbonation.XRD Analysis showed that the WC particles by different rate have the hexagonal strutcture.With the heating rate of 1.7K/min,the dispersion and pore structure of the WC particles are superior to those of other heating rates including the values reported in the literature.Furthermore at this heating rate,Pt-WC/C prepared showed the highest electrocatalytic activity for methanol electrochemical oxidation,the mass activity is 584mA/mg-Pt,compared with 500 mA/mg-Pt and 390 mA/mg-Pt with the tungsten carbide prepared at the heating rate of 1.0K/min,and 3.3 K/min,respectively.