電化學沉積法製備銅-氧化亞銅奈米帶於光陰極材料之應用

Abstract

於本論文中，我們利用電化學沉積法，在網版印刷碳電極（Screen-printed carbon electrode, SPCE）上以氯化銅、硝酸與十六烷基三甲基氯化銨（Cetyltrimethylammonium chloride, CTAC）的溶液為電解液，在兩電極系統中施加2.0 V的偏壓並以冷卻循環水槽控溫290 K，反應48小時候可得到帶寬約30-100 nm間，厚度小於10 nm的奈米銅帶（CuNB），於此奈米銅帶上再進一步藉由熱氧化法（Thermal oxidation）在空氣中加熱數小時可得到銅-氧化亞銅奈米帶。 銅-氧化亞銅奈米帶的高表面積可在電解液與電極界面上增加電子與離子傳遞的效率而幫助光電流的產生，此外，此種金屬-半導體的結構除了可以藉由Schottky barrier的存在增加氧化亞銅光電流的產生，銅的部分還可以幫助傳輸照光產生之電子，並減少光電子於氧化亞銅的表面進行還原反應產生銅金屬顆粒而產生的漏電現象。實驗結果顯示銅-氧化亞銅奈米帶的光電流穩定性高達96.5%，光電流值最高可達到 0.125 mA/cm2，而目前所知與氧化亞銅及其複合材料相關文獻中的有提及光電流穩定性者為75%[2F ]到92%[3F ]，而光電流值則在0.05 mA/cm2 [3]到5.7 mA/cm2 [4]之間。本研究利用簡單的電化學沉積與熱氧化法兩步驟製備了具高表面積的銅-氧化亞銅奈米帶，並展現出極佳的光電流穩定性，預期本材料於光電池的陰極部分具有極高的應用潛力。

Copper nanobelts (CuNB) were electrochemically deposited on screen-printed carbon electrode (SPCE, geometric area 0.196 cm2) by applying a bias 2.0 V in a solution containing CuCl2(aq), HNO3(aq) and cetyltrimethylammonium chloride (CTAC) at 290K. The as-prepared nanobelts were annealed under air to oxidize the Cu surface to form Cu-Cu2O nanobelts. Photoelectrochemical properties of Cu2O were investigated through cyclic voltammetry (CV) and irradiated under UV-Vis light to measure the photocurrent. The stability of the photocathode is measured with chopped light illumination over 20 minutes at 0 V. The Cu-Cu2O nanobelts showed extremely good photocurrent stability of 95.6%. The surface Cu2O layer introduced electrons into the Cu core, as a result, the decreasing of the photocurrent due to the generation of surface Cu nanoparticles is avoided. The photocurrents at 0 V were 0.052 mA/cm2 to 0.125 mA/cm2 .These were among the highest reported values from 0.05 mA/cm2[0F ] for pure Cu2O to 5.7 mA/cm2 [1F ] for multilayer configuration of Cu2O and other semiconductors. The observations were attributed to the property of Schottky junction at the interface of Cu-Cu2O. With their high photocurrent stability, the Cu-Cu2O nanobelts were expected to be a potential photocathode material.