华东理工大学王海丰团队报道了减弱的界面氢键连通性驱动水/板钛矿TiO₂界面上选择性光催化水氧化成H₂O₂。相关研究成果发表在2024年2月22日出版的《美国化学会杂志》。

通过双电子光催化水氧化反应（WOR）形成H₂O₂是重要的，但遇到了与四电子析氧反应的竞争。最近的研究显示了H₂O₂选择性的晶相依赖性，其中与常见的金红石相TiO₂（r-TiO₂）相比，高纯度板钛矿TiO₂（b-TiO₂）表现出显著的H₂O₂选择性。然而，由于与固液界面系统和激发态化学相关的复杂性，这种结构诱导的选择性偏好的起源仍然难以捉摸。

该文中，研究人员采用第一性原理分子动力学模拟和微观动力学分析，对WOR在水/b-TiO₂（210）和水/r-TiO₂界面的选择性机制进行了全面的研究。有趣的是，结果表明，与r-TiO₂（110）相比，b-TiO₂（210）本身的固有催化能力并不能提高H₂O₂的选择性。相反，由b-TiO₂（210）表面的人字形局部原子结构调节的界面氢键连接性减弱决定了选择性。具体而言，由于强的水吸附和明显的吸附取向，界面处的氢键连接性减弱（即局部低水密度），可以稳定OH自由基并抑制其去质子化，从而提高H₂O₂的选择性。相反，在r-TiO₂（110）上建立的相对较强的界面氢键连接性加速了OH的去质子化，OH覆盖率比在水/b-TiO₂（210）界面低3个数量级。

该项研究定量地表明，液/固界面的局部氢键结构（水密度）显著影响光催化选择性，这一见解可能为提高H₂O₂选择性提供一种合理的方法。

附：英文原文

Title: Weakened Interfacial Hydrogen Bond Connectivity Drives Selective Photocatalytic Water Oxidation toward H2O2 at Water/Brookite-TiO2 Interface

Author: Guanhua Ren, Min Zhou, Haifeng Wang

Issue&Volume: February 22, 2024

Abstract: The formation of H2O2 through the two-electron photocatalytic water oxidation reaction (WOR) is significant but encounters the competition with the four-electron O2 evolution reaction. Recent studies showed a crystal-phase dependence in H2O2 selectivity, where high purity brookite TiO2 (b-TiO2) exhibits remarkable H2O2 selectivity in contrast to the common rutile phase TiO2 (r-TiO2). However, the origin of such a structure-induced selectivity preference remains elusive, primarily due to the complexities associated with the solid–liquid interface system and excited-state chemistry. Herein, we conducted a comprehensive investigation into the selectivity mechanism of WOR at the water/b-TiO2(210) and water/r-TiO2(110) interfaces, employing first-principles molecular dynamics simulations and microkinetic analyses. Intriguingly, our results reveal that the intrinsic catalytic ability of the b-TiO2(210) itself does not enhance H2O2 selectivity compared to r-TiO2(110). Instead, it is the weakened interfacial hydrogen bond connectivity, modulated by the herringbone-like local atomic structure of the b-TiO2(210) surface, that determines the selectivity. Specifically, this weakened H-bond connectivity (i.e., local low water density) at the interface, owing to the strong water adsorption and distinct adsorption orientation, can stabilize the OH radical and inhibit its deprotonation, leading to an improved H2O2 selectivity. By contrast, the relatively strong interface H-bond connectivity established over r-TiO2(110) accelerates the deprotonation of OH, with the OH coverage being 3 orders of magnitude lower than at the water/b-TiO2(210) interface. This study quantitatively demonstrates that the local H-bond structure (water density) at the liquid/solid interface significantly influences photocatalytic selectivity, and this insight may offer a rational approach to enhance the H2O2 selectivity.

DOI: 10.1021/jacs.3c13402

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.3c13402