Graphene films on MoS2/SiO2/Si substrate for current density performance

Abstract

Photoelectrochemical (PEC) water splitting, that could directly turn sunlight into hydrogen energy, is one of the effective ways for utilising solar energy. Two-dimensional (2D) graphene and transition metal dichalcogenides (TMDCs) have become effective materials for the advancement of photocatalyst due to their different thermal, electrical, optical, and mechanical properties. 2D graphene can be used as a beneficial support or substrate for catalyst, which not only prevents the catalyst from accumulating but also provides more active sites for the catalytic reaction. As a typical layer-structured of TMDC, MoS2 is considered to be a good semiconductor for PEC water splitting due to its highly active edge sites for effective photocatalytic activity. In this study, chemical vapor deposition was used to grow graphene sheets, which were then transferred onto vertical MoS2 nanoflakes on a SiO2/Si substrate using standard transfer process. Raman spectrum confirmed the presence of the graphene and MoS2 on SiO2/Si. The other morphologies and microstructures have been determined by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Current density performed using PEC measurement system indicates that the light current density under the illumination of sunlight on synthesized graphene/MoS2/SiO2/Si is higher compared to the dark current density. The enhanced in current density can be ascribed to the improved light absorption, strong light matter interaction and the capable charge separation of the heterostructure. Thus, graphene/MoS2/SiO2/Si has capability as a photocatalyst in photoelectrochemical water splitting.