2D-Heterostructure assisted activation of MoS2 basal plane for enhanced photoelectrochemical hydrogen evolution reaction

Abstract

As a potential catalyst of hydrogen evolution reaction (HER), molybdenum disulfide (MoS2) is known to have active sites at the edges, whereas its basal plane is inert. Thus activation of basal plane of MoS2 is essential to intensify the HER catalytic activity. Among various strategies, activation of MoS2 basal plane includes defects engineering via sulfur vacancies and hetero-atom doping. However, for optimal activation, requirements of defect concentration become impractically high, which increases defect-induced high charge carrier recombination loss in photoelectrochemical (PEC) HER. Herein, we report basal plane activation of MoS2 by heterostructuring with two-dimensional (2D) MoSe2 for enhanced photoelectrochemical HER. MoS2/MoSe2 heterostructure grown on silicon nanowire (SiNW) array shows 1.2 times higher photocurrent density and 1.36 times higher incident photon-to-current efficiency (IPCE) than pristine MoS2 grown on SiNW array along with 4.44 times higher H2 evolution rate compared to pristine SiNW photocathode. Density functional theory calculations of heterostructure reveal that charge transfer from the MoSe2 layer to the basal plane of MoS2 increases overall electron density resulting in its increased affinity towards proton reduction, which supports the experimental findings. These findings will boost the strategy for basal plane activation by 2D heterostructuring for efficient photoelectrochemical HER.