Pt/TiO_(2)-CN_(x)催化剂中纳米TiO_(2)(A)/(R)相含量的电催化“火山形”效应  

Electrocatalytic“Volcano-Type”Effect of Nano-TiO_(2)(A)/(R)Phase Content in Pt/TiO_(2)-CN_(x)Catalyst

作　　者：崔爱林 白洋 俞宏英 孟惠民 Ai-Lin Cui;Yang Bai;Hong-Ying Yu;Hui-Min Meng(Institute of Advanced Materials and Technology,University of Science and Technology Beijing,Beijing,100083,China)

机构地区：[1]北京科技大学新材料技术研究院,北京100083

出　　处：《电化学》2022年第5期39-48,共10页Journal of Electrochemistry

基　　金：国家重点研究开发计划(编号2017YFA0403000);国家高技术研究开发计划(编号2007AA05Z103)资助。

摘　　要：由于燃料电池催化剂的电催化活性与Pt颗粒尺寸、催化剂载体、辅助催化剂的关系仍不清楚。为此,本文采用FESEM、XRD、BET、TEM和CV等方法,以存在Pt纳米颗粒、CN_(x)纳米线、TiO_(2)辅助催化剂的多成分复杂结构Pt/TiO_(2)-CN_(x)体系为研究对象,进行了TiO_(2)锐钛矿(A)/金红石(R)相含量对Pt电催化剂电化学活性面积的研究。结果表明,TiO_(2)在700 ℃~900 ℃热处理过程中发生锐钛矿-金红石相变,同时伴随着两相晶粒尺寸的长大,锐钛矿相在900 ℃时完全转化为金红石相。TEM结果表明超细小Pt纳米颗粒成功负载在TiO_(2)-CN_(x)载体表面,粒径尺寸范围为1.8~2.8 nm。TiO_(2)(A)/(R)相含量对TiO_(2)-CN_(x)载体的BET比表面积和Pt/TiO_(2)-CN_(x)催化剂真实“有效的”电化学活性面积(ECSA)都存在“火山形”效应。当金红石相含量为25%时,TiO_(2)(25%R)-CN_(x)载体和Pt/TiO_(2)(25%R)-CN_(x)催化剂具有最大的比表面积和最多的电化学活性位点。原因推测可能是随着金红石相含量的增加,当金红石含量为25%时Pt纳米颗粒和TiO_(2)(25%R)-CN_(x)载体之间存在强烈的金属-载体相互作用,可以锚定超细小Pt纳米颗粒,导致Pt/TiO_(2)(25%R)-CN_(x)催化剂具有最高的ECSA。因此,Pt/TiO_(2)(25%R)-CN_(x)较适宜做燃料电池的催化剂。The relationship between the electrochemical activity of fuel cell catalysts and Pt particle size,as well as the catalyst support and co-catalyst is still unclear.In this work,FESEM,XRD,BET,TEM and CV techniques were adopted to investigate the effects of TiO_(2)anatase(A)/rutile(R)phases content on the electrochemical activity of Pt electrocatalyst.The results showed that the anatase-rutile phase transformation occurred during the heat treatment of TiO_(2)at 700~900 ℃ accompanied by the growth of two-phase crystalline size,and anatase was completely transformed into rutile at 900 ℃.TEM results revealed that the ultrafine Pt electrocatalysts with the particle size of 1.8~2.8 nm were successfully prepared over the TiO_(2)-CN_(x)supports.The content of TiO_(2)(A)/(R)phases had a“volcano-type”effect on both the BET surface area of TiO_(2)-CN_(x)supports and the real“effective”electrochemical active surface area(ECSA)of Pt/TiO_(2)-CN_(x)catalysts.When the rutile content was 25%,the TiO_(2)(25%R)-CN_(x)support and Pt/TiO_(2)(25%R)-CN_(x)catalyst had the largest specific surface area and the most electrochemical active sites,respectively.It is speculated that raising the rutile content,there might be a strong metal-support interaction between Pt nanoparticles and TiO_(2)(25%R)-CN_(x)support with the rutile content of 25%,which could anchor the ultrafine Pt nanoparticles,resulting in the highest ECSA of Pt/TiO_(2)(25%R)-CN_(x)catalyst.Therefore,the Pt/TiO_(2)(25%R)-CN_(x)became more suitable as a catalyst for fuel cells.

关 键 词：催化剂 TiO_(2) 锐钛矿 金红石 电化学活性面积 

分 类 号：O643.36[理学—物理化学] TM911.4[理学—化学]