前驱体溶液pH对Pt基催化剂电催化性能的影响

Influence of pH of precursor solution on electrocatalytic performance of Pt-based catalyst

采用微波辅助乙二醇还原法,在pH不同的前驱体溶液中合成了石墨烯负载的平均粒径不同的Pt/G催化剂,研究了pH对催化剂中Pt纳米粒子粒径及分散程度的影响。使用X射线衍射仪、扫描电子显微镜、X射线能量色散谱仪、X射线光电子能谱仪对催化剂性能进行表征,使用电化学工作站对催化剂的电化学性能进行测试。透射电子显微镜分析结果表明:随着前驱体溶液中pH的逐渐增大,Pt纳米粒子粒径逐渐减小;pH为3,7,9,10,11和12时,Pt纳米粒子平均粒径分别为6.03nm、5.11nm、4.86nm、3.88nm、2.98nm和1.73nm。电化学测试结果表明,在pH=11条件下合成的Pt/G催化剂对乙醇电催化氧化性能最优,电化学活性表面积为65.73m^(2)/g,对乙醇氧化的峰值电流密度为461.4A/g,1000s时的稳态电流密度为144.9A/g。与商业催化剂Pt/C(JM)相比,以石墨烯为载体的Pt/G催化剂性能远远超过商业催化剂,尤其当pH=11时,Pt/G催化剂的峰值电流约为商业催化剂的6倍,说明pH是影响Pt基催化剂性能的关键因素。

Graphene-supported Pt nanoparticles with different average grain sizes were synthesized by a microwave-assisted ethylene glycol reduction method under the conditions of different pH values.The effect of the different pH values on the particle size and distribution of Pt was explored.The synthesized catalysts were characterized by X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry,transmission electron microscopy,and X-ray photoelectron spectroscopy.The electrochemical performance of the prepared catalysts was tested by electrochemical workstation.The results showed that Pt particle size decreased with increasing pH value.When the pH values were 3,7,9,10,11 and 12,the average particle sizes were 6.03,5.11,4.86,3.88,2.98 and 1.73 nm,respectively.The catalyst synthesized at pH 11 showed the best electrocatalytic oxidation performance for ethanol.The electrochemical active surface area was 65.73 m^(2)/g.The peak current density of electrocatalytic oxidation of ethanol was 461.4 A/g,and the steady current density at 1000 swas 144.9 A/g.The performance of the graphene-supported Pt catalyst far exceeded that of a commercial Pt-based catalyst,especially when the pH was 11,the peak current of the graphene-based catalyst was six times that of the commercial catalyst.The pH value in the synthesis process was a key factor affecting the performance of catalyst.