Atomic Layer Deposition of TiO<sub>2</sub> on Si Window Enables <i>In Situ</i> ATR-SEIRAS Measurements in Strong Alkaline Electrolytes
Weiyi Zhang, Xian‐Yin Ma, Tian‐Wen Jiang, Xindi Xu, Baoxin Ni, Bin Chen, Yunyu Wang, Kun Jiang, Wen‐Bin Cai
Abstract
The Si window is the most widely used internal reflection element (IRE) for electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), yet local chemical etching on Si by concentrated OH – anions bottlenecks the reliable application of this method in strong alkaline electrolytes. In this report, atomic layer deposition of a 25 nm nonconductive TiO 2 barrier layer on the reflecting plane of a Si prism is demonstrated to address this challenge. In situ ATR-SEIRAS measurement on a Au film electrode with the Si/TiO 2 composite IRE in 1 M NaOH reveals reversible global spectral features without spectral distortion at 1000–1300 cm –1, in stark contrast to those obtained with a bare Si window. By applying this structured ATR-SEIRAS, ethanol electrooxidation on a Pt/C catalyst in 1 and 5 M NaOH is explored, manifesting that such high pH values prevent the adsorption of as-formed acetate in the C2 pathway but not that of CO intermediate in the C1 pathway.