Experimental and first-principles theoretical studies on Ag-doped cuprous oxide as photocathode in photoelectrochemical splitting of water
Experimental and first-principles theoretical studies on Ag-doped cuprous oxide as photocathode in photoelectrochemical splitting of water
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DOI：
10.1007/s10853-013-7770-2
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发表时间：
2013
影响因子：
4.5
通讯作者：
S. Upadhyay;Dipika Sharma;Nirupama Singh;V. Satsangi;R. Shrivastav;U. Waghmare;S. Dass
中科院分区：
文献类型：
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作者：
S. Upadhyay;Dipika Sharma;Nirupama Singh;V. Satsangi;R. Shrivastav;U. Waghmare;S. Dass
采用简单的喷雾热分解法在玻璃衬底上制备了未掺杂和掺银氧化亚铜纳米结构薄膜，并将其用作太阳能水分解光电化学电池的光电阴极。结合实验和基于第一性原理密度泛函理论的计算，用于确定和理解Ag取代对电子结构和PEC性能的影响。采用XRD、FE-SEM、UV-Vis光谱和PEC测试等手段对薄膜进行了表征。DFT计算结果表明，未掺杂的Cu_2 O的价带顶和导带底分别位于布里渊区的中点，表明纯Cu_2 O是直接带隙材料。最小的变化出现在带隙和带隙能量中的Ag掺杂的Cu 2 O系统，保持它仍然是一个直接带隙材料。在主要由Ag 4d态组成的价带中，在−4和−5 eV之间可以看到缺陷带的出现，并且可以通过Ag 4d和O 2 p之间更强的相互作用来解释，这是由于Ag的尺寸更大。银掺杂的样品表现出改善的电导率和四倍的光电流密度增加相对于未掺杂的样品。
Nanostructured thin films of undoped and Ag-doped cuprous oxide were deposited on indium tin oxide-coated glass substrate using simple spray pyrolysis method for their use as photocathode in photoelectrochemical (PEC) cell for solar energy based water splitting. Combination of experiments and first-principles density functional theory based calculations was used to determine and understand the effect of Ag substitution on electronic structure and PEC performance. Thin films were characterized using XRD, FE-SEM, UV–Vis spectroscopy and PEC measurements. The results of DFT calculations show that the top of valence band and bottom of conduction band of undoped Cu2O lie at Г point of brillouin zone, respectively, suggesting that pure Cu2O is a direct band gap material. Minimal changes appear in the band gap and band gap energies in the Ag-doped Cu2O system, keeping it still a direct band gap material. A defect band appearance can be seen between −4 and −5 eV in the valence band consisting mainly of Ag 4d states and can be explained by a stronger interaction between the Ag 4d and O 2p, due to the larger Ag size. Ag-doped samples exhibit improved conductivity and fourfold increase in photocurrent density with respect to undoped samples.