電沉積CoCu合金作為催化二氧化碳還原反應的材料研究

本論文主要以電沉積鈷銅合金作為電催化劑主體，研究其催化選擇和電化學反應性能。第一部分為非原位軟X光吸收光譜的量測，透過螢光偵測（FY）和總電子偵測（TEY）的訊號深度不同，和藉由改變X光進入Si3N4薄膜的方向，探討鈷銅合金表面Co，Cu和O的氧化價態和其表面影響模式，而提出非原位環境下的介面氧化影響。第二部分，透過原位軟X光吸收光譜和電化學石英晶體微量天平的測量，在CO2還原反應(CO2 reduction reaction，CO2RR) 對於電化學還原反應過程中提供全面且即時的理解。並比較氫氣析出過程(Hydrogen evolution reaction，HER)中，化學成分和表面質量的變化，期望找出兩種不同電催化反應的差別性。最後顯示Co:Cu=1:2比例電沉積的鈷銅合金，不僅在HER反應有穩定且適當的電流表現，在CO2RR反應時也表現出相對較高的電流效率。此論文提供原位X光吸收光譜的電子組態和化學價態的觀察，經由不同電化學還原過程再搭配上物理特性的對照，對於電化學催化反應能有更深入的理解

關鍵字

CO2還原；析氫反應；原位X光吸收光譜；電化學石英晶體微天平

並列摘要

In the thesis, to propose the electrodeposited cobalt-copper alloy (CoCu alloy) for understanding the inter-correlation is studied by the catalytic performance and electrochemical reaction properties. The first part is ex-situ soft X-ray absorption spectrum measurement for the electrodeposited alloy. Since the X-ray direction into the Si3N4 window is reversible by rotating the holder, the valence state and surface effect of CoCu alloy for Co, Cu, and O elements is determined by the different signal depths between fluorescence yield (FY) and total electron yield (TEY) for the interface or bulk side. Thus, it verifies that the ex-situ reaction condition induces the surface oxidation as exposing to the air. The second part, we combine in-situ soft X-ray measurement and Electrochemical Quartz Crystal Microbalance (EQCM) methods to monitor the role of alloy catalyst in the CO2 reduction reaction(CO2RR) and hydrogen evolution reaction(HER). The operando result provides a comprehensive and real-time observation during the electrochemical reduction reaction process, in specific for chemical composition、surface quality, surface resistance formation, in order to estimate the divergence of electrochemical reaction. In the end, for HER reaction or CO2RR reaction, we point out that Co:Cu=1:2 alloy has appropriate current performance and structural stability. We provide an electronic configuration of the in-situ X-ray absorption spectrum for the real-time probing into the chemical valence state. Under the electrochemical reduction relative to the catalytic reaction, the insight into physical and chemical property is deeply understood and discussed.