He Ye, Dai Sheng, Sheng Jianping, Ren Qin, Lv Yao, Sun Yanjuan, Dong Fan
School of Resources and Environment, University of Electronic Science and Technology of China, Chengdu 611731, China.
Research Center for Carbon-Neutral Environmental & Energy Technology, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, China.
Proc Natl Acad Sci U S A. 2024 Jun 18;121(25):e2322107121. doi: 10.1073/pnas.2322107121. Epub 2024 Jun 10.
The photocatalytic CO-to-CH conversion involves multiple consecutive proton-electron coupling transfer processes. Achieving high CH selectivity with satisfactory conversion efficiency remains challenging since the inefficient proton and electron delivery path results in sluggish proton-electron transfer kinetics. Herein, we propose the fabrication of atomically adjacent anion-cation vacancy as paired redox active sites that could maximally promote the proton- and electron-donating efficiency to simultaneously enhance the oxidation and reduction half-reactions, achieving higher photocatalytic CO reduction activity and CH selectivity. Taking TiO as a photocatalyst prototype, the operando electron paramagnetic resonance spectra, quasi in situ X-ray photoelectron spectroscopy measurements, and high-angle annular dark-field-scanning transmission electron microscopy image analysis prove that the V on TiO as initial sites can induce electron redistribution and facilitate the escape of the adjacent oxygen atom, thereby triggering the dynamic creation of atomically adjacent dual-vacancy sites during photocatalytic reactions. The dual-vacancy sites not only promote the proton- and electron-donating efficiency for CO activation and protonation but also modulate the coordination modes of surface-bound intermediate species, thus converting the endoergic protonation step to an exoergic reaction process and steering the CO reduction pathway toward CH production. As a result, these in situ created dual active sites enable nearly 100% CH selectivity and evolution rate of 19.4 μmol g h, about 80 times higher than that of pristine TiO. Thus, these insights into vacancy dynamics and structure-function relationship are valuable to atomic understanding and catalyst design for achieving highly selective catalysis.
光催化CO到CH的转化涉及多个连续的质子-电子耦合转移过程。由于低效的质子和电子传递路径导致质子-电子转移动力学迟缓，因此在实现高CH选择性的同时保持令人满意的转化效率仍然具有挑战性。在此，我们提出制备原子相邻的阴离子-阳离子空位作为成对的氧化还原活性位点，其可以最大程度地提高质子和电子供体效率，同时增强氧化和还原半反应，从而实现更高的光催化CO还原活性和CH选择性。以TiO作为光催化剂原型，通过原位电子顺磁共振光谱、准原位X射线光电子能谱测量和高角度环形暗场扫描透射电子显微镜图像分析证明，TiO上的V作为初始位点可以诱导电子重新分布并促进相邻氧原子的逸出，从而在光催化反应过程中触发原子相邻的双空位位点的动态形成。双空位位点不仅促进了CO活化和质子化的质子和电子供体效率，还调节了表面结合的中间物种的配位模式，从而将吸热的质子化步骤转化为放热反应过程，并将CO还原途径导向CH生成。结果，这些原位产生的双活性位点实现了近100%的CH选择性和19.4 μmol g h的析出速率，比原始TiO高出约80倍。因此，这些关于空位动力学和结构-功能关系的见解对于实现高选择性催化的原子理解和催化剂设计具有重要价值。
