Lu Guangxiang, Zhan Chengbo, Cong Rihong, Yang Tao
College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China.
Inorg Chem. 2023 Dec 11;62(49):20062-20071. doi: 10.1021/acs.inorgchem.3c02854. Epub 2023 Nov 29.
Semiconducting photocatalytic overall water splitting and CO reduction are possible solutions to the emerging worldwide challenges of oil shortage and continual temperature increase, and the key is to develop an efficient photocatalyst. Most photocatalysts contain the d, d or dns metals, and a guiding principle is desired to help to distinguish outstanding semiconductors. Here, the d bimetal oxide InGeO was selected as the target. First, density functional theory (DFT) calculations point out that the nonbonding O 2p orbitals dominate the valence band maximum (VBM), and In 5s-O 2s and Ge 4s-O 2s antibonding orbitals are the major components of conduction band minimum (CBM). Moreover, the molecular orbitals were analyzed to consolidate the DFT calculations and make it more understandable for chemists. Due to the very small specific surface area (0.51 m/g) and wide band gap (4.14 eV), as-prepared InGeO did not exhibit any overall water splitting activity; nevertheless, when loading with 1 wt% cocatalyst (i.e., Pt, Pd), the surficial charge recombination can be greatly eliminated and the overall water splitting activity is significantly improved to 33.0(4) and 17.2(7) μmol/h for H and O generation, respectively. The apparent quantum yield (AQY) at 254 nm is 8.28%. This observation is proof that the inherent electronic structure of InGeO is beneficial for the charge migration in bulk. Moreover, this catalyst also exhibits an observable CO reduction activity in pure water, which is a competition reaction with water splitting, anyway, the CH selectivity can be enhanced by loading Pd. This is a successful attempt to unravel the structure-property relationship by combining the analyses on electronic structure and molecular orbitals and is enlightening to further discover good candidates to photocatalysts.
半导体光催化全分解水和CO还原是应对全球石油短缺和持续升温等新挑战的可能解决方案，关键在于开发高效的光催化剂。大多数光催化剂含有d、d或dns金属，需要一个指导原则来帮助区分优秀的半导体。在此，选择d双金属氧化物InGeO作为研究对象。首先，密度泛函理论（DFT）计算指出，非键合O 2p轨道主导价带顶（VBM），In 5s - O 2s和Ge 4s - O 2s反键轨道是导带底（CBM）的主要组成部分。此外，还对分子轨道进行了分析，以巩固DFT计算结果，使其对化学家来说更易于理解。由于所制备的InGeO比表面积非常小（0.51 m²/g）且带隙较宽（4.14 eV），未表现出任何全分解水活性；然而，当负载1 wt%的助催化剂（即Pt、Pd）时，表面电荷复合可大大消除，全分解水活性显著提高，H₂和O₂生成速率分别达到33.0(4)和17.2(7) μmol/h。在254 nm处的表观量子产率（AQY）为8.28%。这一观察结果证明InGeO的固有电子结构有利于体相中的电荷迁移。此外，该催化剂在纯水中也表现出可观的CO还原活性，这是一个与水分解的竞争反应，无论如何，负载Pd可提高CH₄选择性。这是通过结合电子结构和分子轨道分析来揭示结构 - 性能关系的一次成功尝试，对进一步发现优良的光催化剂候选物具有启发性。
