Identifying the active sites in C-N codoped TiO_(2) electrode for electrocatalytic water oxidation to produce H_(2)O_(2)

C-N共掺杂TiO_(2)电极电解水产H_(2)O_(2)的催化机制

Unveiling the active site of an electrocatalyst is fundamental for the development of efficient electrode material.For the two-electron water oxidation to produce H_(2)O_(2),competitive reactions,including four-and one-electron water oxidation and surface reconstruction derived from the high-oxidative environment co-existed,leading to great challenges to identify the real active sites on the electrode.In this work,Ti/TiO_(2)-based electrodes calcined under air,nitrogen,or urea atmospheres were selected as electrocatalysts for two-electron water oxidation.Electrochemical analyses were applied to evaluate the catalytic activity and selectivity.The morphological and current change on the electrode surface were determined by scanning electrochemical microscopy,while the chemical and valence evolutions with depth distributions were tested by XPS combined with cluster argon ion sputtering.The results demonstrated that Ti/TiO_(2) nanotube arrays served as the support,while the functional groups of carbonyl groups and pyrrolic nitrogen derived from the co-pyrolysis with urea were the active sites for the H_(2)O_(2) production.This finding provided a new horizon to design efficient catalysts for H_(2)O_(2) production.

在两电子电解水产H_(2)O_(2)过程中,电极表面存在四电子和一电子水氧化等竞争反应,同时在强氧化环境中电催化剂会发生表面重构,这对其活性位点的解析带来了很大困难。本文基于Ti/TiO_(2)基电极,在空气、氮气或尿素不同环境煅烧后作为H_(2)O_(2)电催化剂,通过电化学测试评估其催化的活性与反应选择性;借助扫描电化学显微镜和XPS氩离子束溅射等手段,分析了电极表面形貌和电流变化,以及在深度上化学组分的演变。结果表明,Ti/TiO_(2)纳米管阵列作为基底,其与尿素共热解得到的羰基和吡咯氮官能团是电解水产H_(2)O_(2)的关键活性位点。研究结果为设计高效的H_(2)O_(2)电催化剂提供了新的借鉴。