CoS grafted 1 T-phase dominated WS ultrathin nanosheet arrays for highly efficient overall water splitting in alkaline media.

Developing the earth-abundant transition metal-based bifunctional electrocatalysts for water splitting and renewable energy devices has attracted much attention. Herein, we report a 1 T-WS in ultrathin nanosheet arrays grafted with CoS on conductive carbon cloth (CC) (1 T-CoS-WS/CC) through a feasible in-situ growth and vulcanization. The optimized 1 T-CoS-WS/CC catalyst exhibits an impressive electrocatalytic activity and remarkable stability with the oxygen/hydrogen evolution reaction (OER/HER: 278/75 mV for 10 mA cm). It also showed the small Tafel slope values of 61.7 and 58.4 mV dec, respectively. Additionally, the 1 T-CoS-WS/CC achieved 1.59 V@10 mA cm in alkaline media superior to the most previously reported non-precious metal electrocatalysts. The outstanding performance could be attributed to the synergy between heterostructures of CoS and 1 T-WS modifying the electronic structure to accelerate water splitting kinetics. Thus, this work presents a rational design of scalable, high-efficiency, stable water splitting electrocatalysts based on WS.