Exciton Manipulation for Enhancing Photoelectrochemical Hydrogen Evolution Reaction in Wrinkled 2D Heterostructures
Dr. Raman Sankar and his group, in collaboration with Prof. Yang-Fang Chen and Prof. Mario Hofmann, (National Taiwan, University) investigate 2D materials’ junctions have demonstrated capabilities as metal-free alterna-tives for the hydrogen evolution reaction (HER). To date, the HER has been limited to heterojunctions of different compositions or band structures. Here, the potential of local strain modulation based on wrinkled 2D heterostruc-tures is demonstrated, which helps to realize photoelectrocatalytically active junctions. By forming regions of high and low tensile strain in wrinkled WS2monolayers, local modification of their band structure and internal electric field due to piezoelectricity is realized in the lateral direction. This structure produces efficient electron–hole pair generation due to light trapping and exciton funneling toward the crest of the WS2 wrinkles and enhances exciton separation. Additionally, the formation of wrinkles induces an air gap in-between the 2D layer and substrate, which reduces the interfacial scattering effect and consequently improves the charge-carrier mobility. A detailed study of the strain-dependence of the photocatalytic HER process demonstrates a 2-fold decrease in the Tafel slope and a 30-fold enhancement in exchange current density. Finally, optimization of the light absorption through function-alization with quantum dots produces unprecedented photoelectrocatalytic performance and provides a route toward the scalable formation of strain-modulated WS2 nanojunctions for future green energy generation.
Journal Links: https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202210746