Effect of work-function and morphology of heterostructure components on CO2 reduction photo-catalytic activity of MoS2-Cu2O heterostructure

Abstract

Photocatalysis possesses a high potential to utilize solar energy to meet the rising energy demands, however it suffers from various challenges such as fast recombination of the photo-generated electron–hole pairs and low thermodynamic reaction feasibility in the low band-gap materials. Rationally engineered heterostructure photocatalysts possess higher activity compared to their individual components primarily due to spatial separation of photo-generated electron–hole pairs. In this work, we synthesized several MoS2-Cu2O heterostructures, by modulating the electronic and structural properties of the heterostructure components. Heterostructures formed using MoS2 with p-type intrinsic conductivity has shown higher photocatalytic activity, with methanol production yield up to 76 μmol.gcat−1.h−1, compared to n-type MoS2-based heterostructures due to direct Z-scheme and type-II charge transfer mechanism of photo-generated electron–hole pairs respectively. Further, heterostructures formed with Cu2O nanoparticles of cubic morphology with dominantly {100} facets shows (a) higher binding affinity with MoS2 (b) lower recombination of photo-generated electron–hole pairs and (c) higher methanol yield, compared to Cu2O nanoparticles with cubo-octahedron morphology with dominantly {111} facets. This study highlights the important role of work-function and morphology of the heterostructure components in modulating the photo-activity and paves the way for the rational engineering of heterostructure photocatalysts.