Exciton Manipulation for Enhancing Photo-electrochemical Hydrogen Evolution Reaction in Wrinkled 2D Heterostructures.

2D materials' junctions have demonstrated capabilities as metal-free alternatives for hydrogen evolution reaction (HER). To date, HER has been limited to heterojunctions of different compositions or structures. The potential of local strain modulation based on wrinkled 2D heterostructures is demonstrated here that helps to realize photoelectrocatalytically active junctions. By forming wrinkled regions of high and low tensile strain in WS 2 monolayers, local modification of its band structure and internal electric field due to piezoelectricity are created in the lateral direction. This structure produced efficient electron-hole pair generation due to light trapping and exciton funneling towards the crest of the WS 2 wrinkles and enhanced exciton separation. Additionally, the formation of wrinkles induces an air gap in-between the 2D layer and substrate which reduces the interface scattering effect and consequently enhances the charge carrier mobility. A detailed study of the strain-dependence of photocatalytic HER demonstrates a two-fold enhancement in the Tafel slope and a 30-fold enhancement in exchange current density. Finally, optimization of the light absorption through functionalization with quantum dots and 2D heterojunction produces unprecedented photo-electrocatalytic performance and provides a route towards the scalable formation of strain-modulated WS 2 nano-junctions for future energy generation. This article is protected by copyright. All rights reserved.