Shandong Provincial Key Laboratory of Monocrystalline Silicon Semiconductor Materials and Technology, Shandong Universities Engineering Research Center of Integrated Circuits Functional Materials and Expanded Applications, College of Chemistry and Chemical Engineering, Dezhou University, Dezhou 253023, P. R. China.
Collaborative Innovation Center for Advanced Organic Chemical Materials Co-constructed by the Province and Ministry, Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, P. R. China.
Phys Chem Chem Phys. 2023 Mar 29;25(13):9264-9272. doi: 10.1039/d2cp05457d.
Experimental research demonstrates that surface hydroxyl groups can boost TiO's ability to split water but the water splitting mechanism and roles of hydroxyl groups are still not clear. The hydroxyl groups formed by HO or H cracking on pure TiO surfaces are represented by types I (OH1) and II (OH2), respectively. Six types of hydroxylated TiO surfaces of anatase (101), rutile (110), and brookite (210) with OH1 and OH2 hydroxyl groups were constructed. The mechanism of the water oxidation process on the hydroxylated TiO surfaces was systematically investigated through density functional theory calculations. The variation and significant roles of hydroxyl groups in the mechanism of the oxygen evolution reaction (OER) and product selectivity were discussed. All hydroxylated TiO surfaces eventually tend to produce oxygen through a four-electron/proton process, which is fundamentally different from the OER process on pure TiO surfaces from a thermodynamic standpoint. The lowest surface overpotential of R-110-OH1 is 0.53 V, the highest surface overpotential of B-210-OH2 is 1.49 V, and the surface overpotentials of other hydroxylated TiO are between 0.5 and 1.5 V. Rutile (110) and brookite (210) have hydroxyl groups of the OH1-type that are more conducive to the OER process. This study investigates the mechanism of water splitting on the surface of hydroxylated TiO, allowing for a deeper understanding of the function of surface hydroxyl groups in the OER process as well as providing instructions for future research into the development of effective water-splitting catalysts based on hydroxylated TiO surfaces.
实验研究表明，表面羟基基团可以提高 TiO 分解水的能力，但水分解的机制和羟基的作用仍不清楚。HO 或 H 在纯 TiO 表面上断裂形成的羟基基团分别表示为 I 型（OH1）和 II 型（OH2）。构建了锐钛矿（101）、金红石（110）和板钛矿（210）的六种具有 OH1 和 OH2 羟基的氧化钛表面。通过密度泛函理论计算系统研究了水氧化过程在羟基化 TiO 表面上的机制。讨论了羟基基团在析氧反应（OER）和产物选择性机制中的变化和重要作用。所有羟基化 TiO 表面最终都倾向于通过四电子/质子过程产生氧气，这从热力学角度来看与纯 TiO 表面的 OER 过程根本不同。R-110-OH1 的最低表面过电势为 0.53V，B-210-OH2 的最高表面过电势为 1.49V，其他羟基化 TiO 的表面过电势在 0.5 到 1.5V 之间。金红石（110）和板钛矿（210）具有更有利于 OER 过程的 OH1 型羟基基团。本研究探讨了羟基化 TiO 表面上水分解的机制，使人们更深入地了解表面羟基基团在 OER 过程中的功能，并为未来基于羟基化 TiO 表面开发有效水分解催化剂的研究提供了指导。
