Photoelectrochemical performances of the cubic AgSnSe2 thin film electrodes created using the selenization of thermal evaporated Ag-Sn metal precursors

摘要

In this study, we prepared the cubic AgSnSe2 thin film photoelectrodes on substrates using the selenization of Ag-Sn metal precursors and examined the influence of silver content in samples on their photoelectrochemical properties in the aqueous solution. With the selenization temperature kept at 410 degrees C for 1 h in the selenization apparatus, the cubic AgSnSe2 samples can be obtained. The results of phase characterization show that the phase change from the cubic AgSnSe2 to the cubic Ag8SnSe6 phase takes place at the selenization temperature between 425 to 440 degrees C. The optical energy band gaps, carrier concentrations, and mobilities of samples are in the range of 1.24-1.30 eV, 1.75 x 10(18) -4.68 x 10(19) cm(-3), and 43-253 cm(2)/V/s, respectively. It was found that the sample with the [Agy[Ag+Sn] molar ratio of 0.48 had a maximum photo-enhancement current density of 1.26 mA/cm(2) at an external bias of +1.23 V vs. the reverse hydrogen electrode in the 0.35M Na2S +0.25 M K2SO3 aqueous solution. The electrochemical impedance spectra of samples in the aqueous solution containing S2- and SO32- ions were also employed to examine the possible reaction mechanisms taking place at the sample surfaces. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.