High Efficiency Epitaxial-Graphene/Silicon-Carbide Photocatalyst with Tunable Photocatalytic Activity and Bandgap Narrowing

Abstract

A novel way of tuning photocatalytic activity and bandgap narrowing in epitaxial graphene/silicon carbide (EG/SiC) yields high efficiency photocatalyst. Graphitization of SiC by high-temperature thermal decomposition method with different annealing time forms sets of EG/SiC composites having different quality of graphene layers, confirmed by Raman spectroscopy. The Raman intensity ratio of the 2D band to the G band, I2D/IG, represents a measure of quality and quantity of graphene and heterojunction interface layer between EG and SiC. Experimental results reveal that I2D/IG plays a crucial role in tuning the bandgap and enhancement of photocatalytic activity of EG/SiC composites in a systematic manner irrespective of crystal structure or size of the SiC particles. In addition, EG/SiC shows intense broad background absorption in the visible range with increasing I2D/IG. The suitable selection of I2D/IG for EG/SiC gives excellent photocatalytic activity under UV light, up to ≈1000% enhancement and remarkable bandgap narrowing, upto 2 eV and even lesser, which is more than ≈30% reduction, relative to the as received SiC. The efficient control of the electronic structure in such EG/SiC heterojunctions obtained by tailoring the structural parameter I2D/IG opens up promising pathway for bandgap engineering and enhancement of photocatalytic activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim