Hieratical Cu2SnS3 (CTS) Nanostructure As a Highly Efficient Visible Light Photocatalyst for CO2 Reduction to Solar Fuels

Abstract

The conversion of greenhouse CO2 gas into value added chemicals using solar energy or photocurrent derived from visible light is known as artificial photosynthesis. Recently, the production of solar fuel through artificial photosynthesis has been gained tremendous attention due to their fascinating potential in environmental and energy-related application. In CO2 photoreduction technology, the major challenge is the low efficiency of the photocatalyst. Several wide band gap and hybrids carbonaceous materials have been demonstrated as photocatalyst for CO2 reduction. However, in real application these photocatalyst materials are far away from the actual requirement due to the low quantum efficiency and lack of selectivity. Thus, it is a great challenge to develop a potential low-cost photocatalyst for a high CO2 reduction efficiency and produce desire solar fuel under visible light. Last few years several metal sulfides like MoS2, CuS, Cu2S, ZnS and their composite have been attracted considerable attention as a photocatalyst due to their good optical property, high absorption coefficient. However, the application of these perfect semiconductors for photocatalytic CO2 reduction to solar fuels may be limited due to their high interfacial electron-hole recombination process. Recently, Cu-Sn-S ternary semiconductor system has been attracted for its potential contribution as a light absorber layer in photovoltaic application. Cu2SnS3 (CTS) is a ternary p-type semiconductor with a high absorption coefficient. The observed optical band edge of CTS is around 1.4 eV, nearly ideal for solar-energy harvesting. In this study, CTS nanostructure has been demonstrated as a photocatalyst for photocatalytic CO2 reduction to solar fuels under visible light. The ternary CTS nanostructure was obtained from the hydrothermal process and characterized by XRD, Raman spectroscopy, UV-Vis spectroscopy and SEM technique. The photocatalytic activity of the CTS nanostructure hybrid with different S composition was measured in the gas phase CO2 photoreduction under visible-light irradiation. Ethanol has been found to be major product as a high selectivity and efficiency from the photocatalytic CO2 reduction. The observed ethanol formation rate is around 5.6 μmol/g-cat.hr. Detailed investigation on the optimum phase composition, its nanoarchitectures and possible mechanism for the selective solar fuel generation will be discussed. References Nanoscale, 5, 262, (2013) Nano letters, 14, 6097, (2014)