Transparent Ultramicroelectrodes for Studying Interfacial Charge-Transfer Kinetics of Photoelectrochemical Water Oxidation at TiO 2 Nanorods with Scanning Electrochemical Microscopy
Transparent Ultramicroelectrodes for Studying Interfacial Charge-Transfer Kinetics of Photoelectrochemical Water Oxidation at TiO 2 Nanorods with Scanning Electrochemical Microscopy
复制标题
用扫描电化学显微镜研究 TiO 2 纳米棒光电化学水氧化界面电荷转移动力学的透明超微电极
DOI：
10.1021/acs.analchem.1c02598
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发表时间：
2021
影响因子：
7.4
通讯作者：
Pan, Shanlin
中科院分区：
文献类型：
--
作者：
Li, Xiao;Pan, Shanlin
扫描电化学显微镜（SECM）已广泛应用于光电化学（PEC）系统表面和界面的电化学分析。半导体光电极具有明确的几何形状和与 SECM 尖端相当的活性表面积，对于准确量化界面电荷转移活动和光电化学产生的氧化还原物质非常需要，其中平面半导体表面上由于传质梯度和非局域电子转移引起的展宽效应可以最小化。在这里，我们提出了一个新开发的平台作为用于研究半导体 PEC 活动的 SECM 基板，该平台基于使用两步光刻图案化和离子铣削方法制造的透明超微电极（UME）。这种具有 25 μm 凹盘形状的透明 UME 通过 SECM 进行了全面表征，通过与 COMSOL Multiphysics 中有限元模拟的理论结果进行比较，量化 IrCl62/IrCl63 的界面电荷转移速率。当涂有 TiO2 纳米棒作为模型半导体材料时，透明 UME 可通过同时采样尖端和基底电流信号，以 SECM 反馈模式量化催化 PEC 水氧化。这项透明的 UME-SECM 研究提供了对电位依赖性 PEC 水氧化反应机制的见解，以及对水氧化和 SECM 尖端产生的氧化还原介体的光电流贡献的定量分析。透明的 UME-SECM 方法可以扩展到其他 SECM 操作模式，例如用于了解 PEC 系统的电极表面和界面动态的表面询问。
Scanning electrochemical microscopy (SECM) has been extensively applied to the electrochemical analysis of the surfaces and interfaces of a photoelectrochemical (PEC) system. A semiconductor photoelectrode with a well-defined geometry and active surface area comparable to SECM’s tip is highly desired for accurately quantifying interfacial charge-transfer activities and photoelectrochemically generated redox species, where the broadening effects due to the mass transfer gradient and nonlocal electron transfer at a planar semiconductor surface can be minimized. Here, we present a newly developed platform as a SECM substrate for investigating semiconductor PEC activities, which is based on a transparent ultramicroelectrode (UME) fabricated by using two-step photolithographic patterning and ion milling methods. This transparent UME with a 25 μm recessed disk shape is fully characterized with SECM for quantifying the interfacial charge-transfer rates of IrCl62–/IrCl63–by comparing with theoretical results from finite element simulations in COMSOL Multiphysics. When coated with TiO2nanorods as a model semiconductor material, the transparent UME can be used to quantify the catalytic PEC water oxidation in a feedback mode of SECM by sampling tip and substrate current signals simultaneously. This transparent UME–SECM study provides insights into the potential-dependent PEC water oxidation reaction mechanism and the quantitative analysis of photocurrent contributions from water oxidation and the SECM tip-generated redox mediator. The transparent UME–SECM method can be potentially expanded to other SECM operation modes such as surface interrogation for understanding the dynamics of the electrode surfaces and interfaces of a PEC system.