Defect Engineering Via Gamma Irradiation in Scalable Mechanical Exfoliation TMDs Thin Films for Improved Electrocatalytic Hydrogen Evolution

This study explores a novel and efficient van der Waals thin-film deposition method, called Automatic Mechanical Exfoliation (AME), and its application in hydrogen evolution reaction (HER). Compared to traditional physical deposition techniques, AME offers significant advantages: it is simpler, more cost-effective, and significantly faster, enabling the deposition of large-area (>5 cm(2)) coatings exhibiting superior catalytic activity towards HER. To demonstrate its versatility, we comprehensively characterized large-area TMD thin films (MoS2/NbS2, NbS2, TiS2, MoSe2, MoS2, and WS2) using various techniques. Our AME-grown TMD thin films delivered improved HER performance, with lower Tafel slopes compared to previously reported values. To further enhance their activity, we irradiated the films with gamma radiation, leading to a remarkable improvement across all studied TMDs materials (e.g., an average increase of 30 % in exchange current density). Notably, NbS2 thin films and MoS2/NbS2 heterostructures exhibited excellent performance after irradiation, achieving low Tafel slopes (81 mV/dec and 85 mV/dec, respectively), starting overpotentials (-56 mV and -24 mV vs RHE, respectively), high exchange current densities (10.39 mu A cm(-2) and 625.2 mu A cm(-2), respectively), and turnover frequencies (0.021 s(-1) and 0.95 s(-1), respectively). These findings suggest that gamma irradiation can be a powerful tool for defect engineering in TMDs, creating additional active sites and demonstrably enhancing their catalytic efficiency for HER.