A phase transition-induced photocathodic p-CuFeO 2 nanocolumnar film by reactive ballistic deposition
A phase transition-induced photocathodic p-CuFeO 2 nanocolumnar film by reactive ballistic deposition
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反应弹道沉积相变诱导光阴极p-CuFeO 2 纳米柱薄膜
DOI：
10.1039/d1nj04656j
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发表时间：
2022
影响因子：
3.3
通讯作者：
Kim, Chang Woo
中科院分区：
文献类型：
--
作者：
Ramacharyulu, P. V.;Lee, Yong Ho;Kawashima, Kenta;Youn, Duck Hyun;Kim, Jun-Hyuk;Wygant, Bryan R.;Mullins, C. Buddie;Kim, Chang Woo
本研究采用反应弹道沉积技术，将沉积角度固定为85°，在氧气气氛中，在掺氟氧化锡衬底上制备了垂直结构的铜-铁-氧纳米柱阵列。扫描电子显微镜图像显示存在单个柱的阵列。样品在Ar(CuFeO2)气氛中于6 5 0℃退火2 h后，在AM 1.5G光照下，在0.4V和1M氢氧化钠中的光电流密度分别为0.2 2 mA cm−2和0.12 mA cm−2。这里，在650℃的Ar气氛中退火的薄膜具有阴极光电流的p型特性，而在空气中退火的薄膜具有阳极光电流的n型特性。电导率从n型向p型的转变是由非晶态CuFeO向钙铁矿型CuFeO2的相变引起的。X射线光电子能谱表明，p-CuFeO2的阴极光电流的产生也可能是由于Cu2+/Cu2+氧化还原对的存在。
In the present study, Cu–Fe–O vertical nanocolumnar structured arrays are deposited on fluorine-doped tin oxide substrates by the reactive ballistic deposition technique in an oxygen atmosphere by fixing the deposition angle at 85°. The scanning electron microscopy images show the presence of arrays of individual columns. The photocurrent density of the Cu–Fe–O sample annealed at 650 °C for 2 h in argon (CuFeO2) is determined to be −0.22 mA cm−2 at 0.4 V versus RHE in 1 M NaOH under AM 1.5 G illumination, while the same annealed in air exhibits a photocurrent density of 0.12 mA cm−2 at 1.23 V versus RHE. Here, the film annealed in an argon atmosphere at 650 °C exhibits a p-type characteristic with cathodic photocurrent, while the film annealed in air depicts an n-type characteristic with anodic photocurrent. The switch in conductivity from n-type to p-type is induced by the phase transition from amorphous Cu–Fe–O to delafossite CuFeO2. The generation of cathodic photocurrent from p-CuFeO2 is also expected to be from the presence of the Cu2+/Cu+ redox couple, which is evidenced by X-ray photoelectron spectroscopy.