Modification of Ag8SnS6 Photoanodes with Incorporation of Zn Ions for Photo-Driven Hydrogen Production

Lin-Ya Yeh,Kong-Wei Cheng

doi:10.3390/catal11030363

Abstract

In this study, Zn ions were incorporated into Ag8SnS6 thin films on glass and indium–tin–oxide-coated glass substrates using chemical bath deposition. Detailed procedures for the growth of Ag–Zn–Sn–S semiconductor films and their optical, physical and photoelectrochemical performances were investigated. X-ray diffraction patterns of samples revealed that kesterite Ag2ZnSnS4 phase with a certain amount of Ag8SnS6 phase can be obtained using ethylenediaminetetraacetic acid disodium salt and trisodium citrate as the chelating agent couples. Images of field-emission scanning electron microscope showed that plate-like microstructures with some spherical aggregates were observed for the sample at low Zn content. It changed to irregular spherical grains with the [Zn]/[Sn] ratios being higher than 0.95 in samples. The energy band gaps of the samples were in the range of 1.57–2.61 eV, depending on the [Zn]/[Sn] molar ratio in sample. From the Hall measurements, the carrier concentrations and mobilities of samples were in the ranges of 6.57 × 1012–1.76 × 1014 cm−3 and 7.14–39.22 cm2/V·s, respectively. All samples were n-type semiconductors. The maximum photoelectrochemical performance of sample was 1.38 mA/cm2 in aqueous 0.25 M K2SO3 and 0.35 M Na2S solutions.

Highlights

The world consumption of fossil fuel has increased dramatically because of the fast expansion of industrialization and population [1]
The applications of renewable energy are good ways to decrease the consumption of fossil fuel, the variations of renewable energy are the major problem for further applications
The possible energy storage systems such as Zn–air batteries, Li-based chargeable batteries or supercapacitors have been developed for several decades in order to balance the variations of these renewable energies, but the limitation of these storage capacities is a major obstacle for further application [3,4,5,6]

Summary

Introduction

The world consumption of fossil fuel has increased dramatically because of the fast expansion of industrialization and population [1]. The main energy sources of industrial applications still come from fossil fuel. To decrease the consumption of fossil fuel, the development and application of renewable energy such as solar, wind, hydropower or geothermal heat have been widely discussed in the academia or the industry [2]. The applications of renewable energy are good ways to decrease the consumption of fossil fuel, the variations of renewable energy are the major problem for further applications. The possible energy storage systems such as Zn–air batteries, Li-based chargeable batteries or supercapacitors have been developed for several decades in order to balance the variations of these renewable energies, but the limitation of these storage capacities is a major obstacle for further application [3,4,5,6]. Converting solar energy into hydrogen gas is a possible way to solve the global energy requirement

Methods

Findings

Discussion

Conclusion