Laser ablation in liquids has been, for the first time, employed to produce oxygen vacancy-modified CoOOH nanosheets for efficient water oxidation.

Molybdenum disulfide (MoS₂) has been recognized as one of the most promising catalysts to replace Pt for hydrogen evolution reaction (HER) electrocatalysis because of the elemental abundance, excellent catalytic potential, and stability. However, its HER efficiency is still below that of Pt. Recent research advances have revealed that the modification of pristine MoS₂ is a very effective approach to boost its HER performance, including improving the intrinsic activity of sites, increasing the number of edges, and enhancing the electrical conductivity. In this review, we focus on the recent progress on the modification strategies of MoS₂ for enhanced electrocatalytic hydrogen evolution. Moreover, some urgent challenges in this field are also discussed to realize the large-scale application of the modified-MoS₂ catalysts in industry.

The edge S sites of thermodynamically stable 2H MoS₂ are active for hydrogen evolution reaction (HER) but the active sites are scarce. Despite the dominance of the basal S sites, they are generally inert to HER because of the low p-band center. Herein, we reported a synergistic combination of phase engineering and NH₄⁺ intercalation to promote the HER performance of MoS₂. The rational combination of 1T and 2H phases raises the p-band center of the basal S sites while the intercalated NH₄⁺ ions further optimize and stabilize the electronic band of these sites. The S sites with regulated band structures afford moderate hydrogen adsorption, thus contributing to excellent HER performance over a wide pH range. In an acid medium, this catalyst exhibits a low overpotential of 169 mV at 10 mA·cm⁻² and Tafel slope of 39 mV·dec⁻¹ with robust stability, superior to most of recently reported MoS₂-based non-noble catalysts. The combined use of in/ex-situ characterizations ravels that the appearance of more unpaired electrons at the Mo 4d-orbital reduces the d-band center which upshifts the p-band center of the adjacent S for essentially improved HER performance. This work provides guidelines for the future development of layered transition-metal-dichalcogenide catalysts.