透由原位電化學技術來探討硫酸銅溶液中電鍍和電溶解效應

The Electro-Deposition/Dissolution of CuSO4 Aqueous Electrolyte Investigated by In Situ Electrochemical Technology

莊程豪(Cheng-Hao Chuang)

《化學》 79卷1期 (2021/03) Pp. 59-68

https://doi.org/10.6623/chem.202103_79(1).013

摘要

本工作使用軟X光吸收光譜、電化學石英微天平、和熱脫附質譜儀技術，觀測如何從pH 4.8硫酸銅溶液中銅離子電鍍生長和溶解的機制。發現電鍍銅過程可產生過氫氧根，穩定住Cu^+氧化態和避免金屬銅（Cu^0）產生。氧化亞銅表面生成羥基氧化物（oxy-hydroxide）形成介面水合氧化物（Cu_2O_(aq)），在後半段中陽極掃描中產生穩定氧化銅（CuO）結構和其Cu^(2+)氧化態，但在更高陽極電壓下，仍出現化學降解和表面溶解現象。臨場電位循環實驗中發現，相對於電鍍過程所需電子數目，溶解過程只收回更少電子數目，原因出自於水催化現象和反應中途所產生質子產物的伴隨效應。

關鍵字

電鍍反應 ； 電溶解反應 ； 原位實驗 ； 軟X光吸收光譜 ； 電化學石英微天平實驗 ； 熱脫附質譜儀技術

並列摘要

This work combines soft X-ray absorption, electrochemical quartz microbalance, and thermal desorption spectroscopy to observe the electrodeposition of copper on the Au electrode in a 4.8 pH CuSO_4 solution. The oxy-hydroxide species formed by the copper electrodeposition, as the unique state (Cu_2O_(aq)) at the solid-liquid interface, stabilizes Cu^+ state and avoids the metallic copper formation (Cu^0). However, the further anodic polarization of oxy-hydroxide surface leads to the formation of CuO, as the formal oxidation state of Cu^(2+). The chemical decomposition and surface dissolution are found at higher anodic potential. Operando cyclic experiment indicates that dissolution process needs less anodic charge than that cathodic charge required for the electrodeposition. A nonreversible process is ascribed to concomitant water splitting and formation of protons during the electrodeposition.

並列關鍵字

Electro-deposition ； Electro-dissolution ； In-situ experiment ； Soft X-ray absorption spectroscopy ； Electrochemical quartz crystal microbalance ； Thermal desorption spectroscopy