聚苯胺对钯催化甲酸电氧化反应的促进作用

摘要

钯基纳米材料是甲酸电氧化反应的优良催化剂.本工作制备了两个系列钯基催化剂,并考察了聚苯胺对钯上甲酸电氧化反应的助催化作用.一种是以聚苯胺为基底,在其表面电沉积钯纳米粒子,制得nPANI/Pd催化剂(n表示聚合苯胺的循环数)；另一种是直接在商业Pd/C催化剂表面电聚合苯胺,制得Pd/CPANI催化剂.结果显示,聚苯胺单独存在时对甲酸电氧化反应没有催化活性,但其可对钯上甲酸电氧化反应呈现明显的促进作用,且促进作用与聚苯胺的厚度(聚合循环数)密切相关.在两个系列催化剂中,15PANI/Pd和Pd/C/20PANI显示出最高的催化性能.15PANI/Pd中钯的质量比催化活性是纯钯催化剂的7.5倍； Pd/C/20PANI中钯的质量比催化活性和本征催化活性分别是商业Pd/C催化剂的2.3和3.3倍.钯催化性能的提升与聚苯胺和钯纳米粒子间的电子效应有关.%Pd-based nanomaterials have been considered as an effective catalyst for formic acid electrooxida-tion reaction (FAOR). Herein, we reported two types of polyaniline (PANI)-promoted Pd catalysts. One was annPANI/Pd electrocatalyst prepared by the electropolymerization of aniline and the electrodeposition of Pd. The other was a Pd/CPANI catalyst prepared by the direct electropoly-merization of aniline on a commercial Pd/C catalyst. The results show that PANI alone has no cata-lytic activity for FAOR; however, PANI can exhibit a significant promoting effect to Pd. The current densities of FAOR on the Pd catalysts with a PANI coating show a significant increase compared with that of the Pd reference catalyst without PANI as a promoter. The promoting effects of PANI are strongly dependent on the electropolymerization potential cycles (n). The highest catalytic ac-tivities for FAOR of all thenPANI/Pd and Pd/CPANI catalysts were those of 15PANI/Pd and Pd/C/20PANI. The mass-specific activity (MSA) of Pd in 15PANI/Pd was 7.5 times that of the Pd catalyst, and the MSA and intrinsic activity of Pd/C/20PANI were 2.3 and 3.3 times that of the Pd/C catalyst, respectively. The enhanced performance of Pd catalysts is proposed as an electronic effect between Pd nanoparticles and PANI.