(Invited) SnS2 Nanostructure As a Highly Efficient Photocatalyst for CO2 Reduction to Solar Fuels

Abstract

Photocatalytic CO2 reduction to solar fuels by artificial photosynthesis is an attractive and effective research area to solve the energy crisis as well as anthropogenic greenhouse emission problems from CO2 emission. In the past several years, many significant efforts have been applied to develop an efficient photocatalyst for the CO2 reduction to hydrocarbons. Among the entire reported photocatalyst several semiconductor materials together with carbonaceous hybrid materials GO, g-C3N4, TiO2/rGO, MoS2/rGO and Cu-GO have been reported as a promising photocatalyst for CO2 reduction to solar fuels conversion because of their comparatively low cost, low toxicity and photocorrosion resistance. However, wide bad gap semiconductor photocatalysts are not enough to use for practical application due to their limited visible light absorption. The promising prospect of these materials is far away from the commercial 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. Since the discovery of graphene, two-dimensional (2D) layered transition metal dichalcogenides (TMDs) nanostructure are playing an important role in the various applications due to their crystal structure, a wide range of chemical compositions and optoelectronic properties. The wide range of electronic properties of TMD semiconductor materials is also promising for catalysis due to their strong correlation between electronic and catalytic properties. Last few years, several narrow band gap metal sulfides such as CdS, PbS, CdSe, MoS2 have been introduced as a photocatalyst or a co-catalyst together with another wide-band gap semiconductor for photocatalytic reaction under visible light. Although CdS and PbS contains sufficient potential characteristics as a photocatalyst, however, they explored less as a commercial photocatalyst due to the toxicity problem of Cd and Pb. Therefore, it's highly desirable to explore non toxic narrow bandgap metal sulfide for photocatalytic CO2 reduction. Among various, metal sulfides SnS2 is one of the narrow bandgap nontoxic semiconductor associate with dichalcogenide family. Recently, it has been attracted for its potential applications as a light absorber layer for desensitized solar cell, gas sensing, energy storage and conversion. SnS2 possesses CdI2 crystal structure, consisting sandwiched S-Sn-S layers bounded by weak van der Waals's interaction. The strong intra- and weak inter-layer inter-actions induce the high anisotropy of 2D SnS2. SnS2 is an n-type semiconductor with a narrow bandgap around 2.2-2.4 eV at room temperature, and high quantum yield, thus it shows several benefits to be a good photocatalyst behavior under visible light. The details photocatalytic performance, high quantum yield and selectivity of solar chemicals will be discussed.