The role of titanium at the interface of hematite photoanode in multisite mechanism: Reactive site or cocatalyst site?

IF 15.7 1区化学 Q1 CHEMISTRY, APPLIED Chinese Journal of Catalysis Pub Date : 2024-09-01 DOI:10.1016/S1872-2067(24)60093-8

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Abstract

Hematite (α-Fe₂O₃) constitutes one of the most promising photoanode materials for oxygen evolution reaction (OER). Recent research on Fe₂O₃ have found a fast OER rate dependence on surface hole density, suggesting a multisite reaction pathway. However, the effect of heteroatom in Fe₂O₃ on the multisite mechanism is still poorly understood. Herein we synthesized Fe₂O₃ on Ti substrates (Fe₂O₃/Ti) to study the oxygen intermediates of OER by light-dark electrochemical scans. We identified the Fe-OH species disappeared and Ti-OH intermediates appeared on Fe₂O₃/Ti when pH = 11−14, which significantly improved the OER performance of Fe₂O₃/Ti. Combined with the density functional theory calculations, we propose that Ti atom acts as cocatalyst site and captures proton from neighboring Fe-OH species under highly alkaline condition, thereby promoting the coupling of Fe=O and reducing the energy barrier of the non-electrochemical step. Our work provides a new insight into the role of heteroatom in OER multisite mechanism based on clarifying the reaction intermediates.

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赤铁矿光阳极界面上的钛在多位点机制中的作用：反应位点还是共催化剂位点？

赤铁矿（α-Fe2O3）是最有前途的氧进化反应（OER）光阳极材料之一。最近对 Fe2O3 的研究发现，OER 的快速速率与表面空穴密度有关，这表明存在多位点反应途径。然而，人们对 Fe2O3 中的杂原子对多位点机制的影响仍知之甚少。在此，我们在钛基底上合成了 Fe2O3（Fe2O3/Ti），并通过光-暗电化学扫描研究了 OER 的氧中间产物。我们发现当 pH = 11-14 时，Fe2O3/Ti 上的 Fe-OH 物种消失，Ti-OH 中间体出现，这显著提高了 Fe2O3/Ti 的 OER 性能。结合密度泛函理论计算，我们认为在高碱性条件下，Ti 原子作为协同催化剂位点，从邻近的 Fe-OH 物种中捕获质子，从而促进了 Fe=O 的耦合，降低了非电化学步骤的能垒。我们的研究在阐明反应中间产物的基础上，对异质原子在 OER 多位点机理中的作用提出了新的见解。

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来源期刊

Chinese Journal of Catalysis 工程技术-工程：化工

CiteScore

25.80

自引率

10.30%

发文量

235

审稿时长

1.2 months

期刊介绍： The journal covers a broad scope, encompassing new trends in catalysis for applications in energy production, environmental protection, and the preparation of materials, petroleum chemicals, and fine chemicals. It explores the scientific foundation for preparing and activating catalysts of commercial interest, emphasizing representative models.The focus includes spectroscopic methods for structural characterization, especially in situ techniques, as well as new theoretical methods with practical impact in catalysis and catalytic reactions.The journal delves into the relationship between homogeneous and heterogeneous catalysis and includes theoretical studies on the structure and reactivity of catalysts.Additionally, contributions on photocatalysis, biocatalysis, surface science, and catalysis-related chemical kinetics are welcomed.