In Situ Porousized MoS 2 Nano Islands Enhance HER/OER Bifunctional Electrocatalysis.

2D molybdenum disulfide (MoS 2 ) is developed as a potential alternative non-precious metal electrocatalyst for energy conversion. It is well known that 2D MoS 2 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 2 into self-supporting nano islands to maximally expose the edges of MoS 2 grains for efficient utilization of the active stable sites at the edges of MoS 2 is reported. The results show that such active, aggregation-free nano islands greatly enhance MoS 2 '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 2 nano islands can generate a current density of 10 mA cm -2 in HER and OER, which is much better than typical nanosheet morphology. Surprisingly, the porous MoS 2 nano islands even exhibit better performance than the current commercial RuO 2 catalyst in OER. This discovery will be another effective strategy to promote robust 2H-phase, instead of 1T/1T'-phase, MoS 2 to achieve efficient endurable bifunctional HER/OER, which is expected to further replace precious metal catalysts in industry.