Na_2CO_3对TiO_2纳米管电极表面光电化学水分解反应的催化作用研究

Sodium Carbonate Catalyzed Photoelectrochemical Water Splitting over TiO_2 Nanotubes Photoanode

光生载流子在半导体/溶液界面处发生的表面复合过程,是制约半导体光电极体系光-电转化效率提高的关键因素之一.本文利用光电流测量和交流阻抗等技术,初步研究了Na2CO3对TiO2纳米管电极表面光电化学水分解反应的催化作用,并对"TiO2/溶液"界面处与阳极析氧有关的光生电荷传输过程及特点进行了探讨.结果表明,在0.5 mol.L-1NaClO4溶液中加入少量的Na2CO3(1mmol.L-1),能够显著促进光生空穴穿过TiO2/溶液界面向溶液中的传输,有效地抑制光生载流子的表面复合过程,从而相应地增大了外电路的光电流,并使TiO2光电极体系的光-电转化效率得到提高.

Surface recombination of the photogenerated electron-hole pairs at semiconductor/electrolyte interface is one of the most essential reasons responsible for lowering photoconversion efficiency （φ） of light to chemical energy for photoelectrochemical （PEC） water splitting reaction. In this paper,the catalytic effect of sodium carbonate on the oxygen evolution reaction（OER） over TiO2 nanotube photoanode during PEC water splitting was investigated by performing photocurrent and ac impedance measurements. It was demonstrated that the addiction of 1 mmol ·L-1 Na2CO3 in 0.5 mol ·L^-1 NaClO4 electrolyte can effectively improve the charge transfer properties for the photogenerated holes across TiO2/electrolyte interface and inhibit the recombination of photogenerated carriers at this interface. As a result, both the measured photocurrent was increased and the photoconversion efficiency was enhanced.