Pseudo metallic (1T) molybdenum disulfide for efficient photo/electrocatalytic water splitting

2D-layered metallic molybdenum disulfide i.e. 1T MoS2 possess prominent electronic conductivity and abundant electrochemically active sites. However, tuning its metastable crystal structure for promoting catalytic performance is a big technical challenge. Here, we reveal the role of the intercalated reducible -NH and -NH2 species as structural stabilizers in supporting the lamellar structure of 1T MoS2, and then propose a novel H2O2-cleaning strategy to reduce the amount of reducible -NH and -NH2 species for modulating the crystallinity and layer thickness of 1T MoS2 without degrading to 2H MoS2. The resultant pseudo-1T MoS2 exhibits larger specific surface area (up by 1.6 times) and higher electron mobility compared to original 1T MoS2, leading to excellent photo/electrocatalytic HER activity. Impressively, pseudo-1T MoS2 achieves high visible-light-driven photocatalytic HER rate of 235.0 mmol·h−1·g−1 in combination with CdS. This work offers an extendable crystal structural fine-tuning approach to promote the catalytic activity of metallic transition metal dichalcogenides.