In Situ Porousized MoS Nano Islands Enhance HER/OER Bifunctional Electrocatalysis.

2D molybdenum disulfide (MoS ) is developed as a potential alternative non-precious metal electrocatalyst for energy conversion. It is well known that 2D MoS has three main phases 2H, 1T, and 1T'. However, the most stable 2H-phase shows poor electrocatalysis in its basal plane, compared with its edge sites. In this work, a facile one-step hydrothermal-driven in situ porousizing of MoS into self-supporting nano islands to maximally expose the edges of MoS grains for efficient utilization of the active stable sites at the edges of MoS is reported. The results show that such active, aggregation-free nano islands greatly enhance MoS 's hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bifunctional electrocatalytic activities. At a low overpotential of 248 and 300 mV, the porous MoS nano islands can generate a current density of 10 mA cm in HER and OER, which is much better than typical nanosheet morphology. Surprisingly, the porous MoS nano islands even exhibit better performance than the current commercial RuO catalyst in OER. This discovery will be another effective strategy to promote robust 2H-phase, instead of 1T/1T'-phase, MoS to achieve efficient endurable bifunctional HER/OER, which is expected to further replace precious metal catalysts in industry.