Poor crystalline MoS₂ with highly exposed active sites for the improved hydrogen evolution reaction performance

Poor crystalline MoS₂/C hollow nanosphere with highly exposed active sites were rationally designed for the enhanced the hydrogen evolution reaction (HER) performance and long-term durability. Polyoxometalates were used as oxidants to spontaneously initiate the polymerization of pyrrole, and served as Mo sources for synthesizing MoS₂ in the following sulfurization, as well as P sources for doping carbon. Solid, hollow, and double-shelled hollow nanoshperes were facilely controlled via improving the annealing temperature, and showing varied HER performance due to the variations in nanostructure, crystallinity, defects, mass transports, etc. It is found that hollow nanospheres annealed at 800 °C exhibited the best HER performance, showing overpotential of 207 mV at 10 mA cm⁻², and Tafel slope of 73 mV dec⁻¹, as well as long-term stability for 25 h. Poor crystalline phase with abundant defective sites and highly accessible surface area possessing highly exposed active sites, as well as the synergistic effects between MoS₂ and N, P-dual doped mesoporous carbon, contributed to improving the HER performance. Present work proved that the smart manipulation of the crystallinity of MoS₂ is an efficient way to prepare high performance HER catalysts, which might be further utilized in photoelectrocatalytic water splitting in comparison to complete amorphous phase.