文献类型：期刊文献

英文题名：Optimally Selecting Photo- and Electrocatalysis to Facilitate CH4 Activation on TiO2(110) Surface: Localized Photoexcitation versus Global Electric-Field Polarization

作者：Zhou, Min[1,2];Wang, Haifeng[1,2]

机构：[1]East China Univ Sci & Technol, Key Lab Adv Mat, Ctr Computat Chem, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Res Inst Ind Catalysis, Shanghai 200237, Peoples R China

年份：2022

卷号：2

期号：1

起止页码：188

外文期刊名：JACS AU

收录：EI(收录号：20225113259044);WOS:【ESCI(收录号:WOS:000772069200019)】；

基金：This project was supported by National Key R&D Program of China (2021YFA1500700), NSFC (2187302 8, 91945302,92045303), National Ten Thousand Talent Program for Young Top-notch Talents in China, Shanghai ShuGuang project (17SG30), and the Fundamental Research Funds for the Central Universities

语种：英文

外文关键词：density functional theory calculation; photocatalysis; electrocatalysis; CH4 activation; electric-field effect; TiO2

摘要：Photo- and electrocatalytic technologies hold great promise for activating inert chemical bonds under mild conditions, but rationally selecting a more suitable method in between to maximize the performance remains an open issue, which requires a fundamental understanding of their different catalytic mechanisms. Herein, by first-principles calculations, we systematically compare the activation mechanisms for the C-H bond of the CH4 molecule on TiO2(110) under the photo- and electrocatalytic modes without or with water involved. It quantitatively reveals that the activation barrier of the C-H bond decreases dramatically with a surprising 74% scale by photoexcitation relative to that in thermocatalysis (1.12 eV), while the barrier varies with a maximum promotion of only 5% even under -1 V/angstrom external electric field (EEF). By detailed geometric/electronic analysis, the superior photocatalytic activity is traced to the highly oxidative lattice O-br(center dot-) radical excited by a photohole (h(+)), which motivates the homolytic C-H bond scission. However, under EEF from -1 V/A to 1 V/A, it gives a relatively mild charge polarization on the TiO2(110) surface region and thus a limited promotion for breaking the weakly polar C-H bond. By contrast, in the presence of water, we find that EEF can facilitate CH4 activation indirectly assisted by the surface radical-like OH* species from the oxidative water cleavage at high oxidative potential (>1.85 V vs SHE), which explains the high energy cost to drive electrocatalytic CH4 conversion in experiment. Alternatively, we demonstrate that more efficient CH4 activation could be also achieved at much lower oxidative potential when integrating the light irradiation. In such a circumstance, EEF can not only promote the h(+) accumulation at the catalyst surface but also help H2O deprotonation to form hydroxide, which can serve as an efficient hole-trapper to generate OH center dot- radical (OH- + h(+) -> OH center dot-), unveiling an interesting synergistic photoelectrocatalytic effect. This work could provide a fundamental insight into the different characteristics of photo- and electrocatalysis in modulating chemical bond cleavage.