Highly efficient CoMoS heterostructure derived from vertically anchored Co5Mo10 polyoxometalate for electrocatalytic overall water splitting

Electrocatalytic overall water splitting is always holding great promise in renewable energy field. It is crucial to fabricate low-cost, earth-abundant and robust bi-functional electrocatalysts for both hydrogen evolution and oxygen evolution reactions. Herein, we report a polyoxometalates (POMs)-based molecular approach to construct Co promoting MoS2-based nanosheets Co5Mo10Sx employing well-defined Co3[Co2Mo10O38H4] as superior precursor. The CoMo-POMs act as pre-assembling molecular platform for the construction and regulation of CoS2-MoS2 heteronanostructure (CoMoS active sites) through precise engineering with atomic level. The Co5Mo10Sx exhibited excellent bi-functional electrocatalytic activity in alkaline solution, with only 36 mV and 153 mV overpotential to achieve 10 mA cm−2 current density for HER and OER, respectively. We demonstrate a two-electrode cell performing water electrolysis in alkaline condition, delivering a current density of 10 mA cm−2 at low cell voltage of 1.51 V. Combined with the theoretical calculations, the superior performance can be attributed to enhanced intrinsic catalytic activity of CoMoS sites, synergistic effect of heterostructure, abundant and defect-rich heterogeneous interfaces. This study provides a feasible strategy to rational design and controllable fabrication of efficient electrocatalysts for renewable energy applications.