Detailed Investigation on the Band Energetics of Nanostructured Zn2SnO4 Electrodes in Aqueous Electrolytes

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• 作者：Huizhi Kou ; Shuming Yang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：March 15, 2012
• 年：2012
• 卷：116
• 期：10
• 页码：6376-6382
• 全文大小：414K
• 年卷期：v.116,no.10(March 15, 2012)
• ISSN：1932-7455

文摘

Band energetics of nanostructured Zn₂SnO₄ electrodes were determined with spectroelectrochemical measurements, and its trap states were investigated with electrochemistry. The flat band edges (E_fb) of nanostructured Zn₂SnO₄ electrodes were highly dependent on pH of electrolyte and measured to be 鈭?.60, 鈭?.73, 鈭?.85, 鈭?.94, and 鈭?.08 V vs saturated Ag/AgCl in 0.5 mol L^鈥? LiClO₄ of pH 3.0, 5.0, 6.9, 10.0, and 13.0, respectively, and followed the Nestain relationship of E_fb = 鈭?.49 鈥?0.046pH, V vs Ag/AgCl. The addition of acetate also changed the E_fb. The E_fb were measured to be 鈭?.48, 鈭?.54, 鈭?.71, 鈭?.86, and 鈭?.03 V in 0.5 mol L^鈥? LiClO₄ and 1.0 mol L^鈥? NaAc of pH 4.0, 5.0, 7.0, 10.0, and 13.2, respectively, and followed a Nestian relationship of E_fb聽= 鈭?.25 鈥?0.060pH, V vs Ag/AgCl, very close to that reported by Wu and Alpuche-Aviles [J. Am. Chem. Soc.2009, 131, 3216]. The time-resolved currents at different applied potentials positive of flat band edge clearly indicate a trap-filling process. Trap state densities are also highly pH dependent. Total trap state densities of 2.79 脳 10¹⁵, 6.75 脳 10¹⁵, and 9.98 脳 10¹⁵ cm^鈥? were determined in 0.5 mol L^鈥? LiClO₄ solutions of pH 3.0, 6.9, and 13.0, respectively, with maximum located at 鈭?.25 V, 鈭?.30 V, and 鈭?.60 V. The trap state densities of 4.17 脳 10¹⁵, 6.88 脳 10¹⁵, and 7.17 脳 10¹⁵ cm^鈥? were calculated in 0.5 mol L^鈥? LiClO₄ and 1.0 mol L^鈥? NaAc solutions of pH 4.0, 7.0, and 13.2, respectively. The results obtained from CVs are in good agreement with that obtained from the measurements of time-resolved currents, and the size of the peak potentials related to the trap states increases dramatically with an increase of pH, indicating that traps are mostly surface-related.