Ion-exchange strategy for fabricating highly dispersed Co–MoS2 on N-doped graphene for efficient bifunctional electrocatalytic water splitting

Recently, the pivotal to electrocatalytic water splitting is developing efficient and earth-abundant electrocatalysts to accelerate the sluggish kinetics of hydrogen and oxygen evolution reactions (HER and OER). In this work, (NH4)2MoS4 derived from polyoxometalates ((NH4)6Mo7O24·4H2O) were immobilized onto the ion exchange resin D314, and highly dispersed Co-molybdenum disulfide (Co–MoS2@NG-4) on nitrogen-doped graphene catalyst was prepared. The optimized Co–MoS2@NG-4 shows excellent electrocatalytic performance for HER and OER. Specifically, the low overpotentials of 202 and 352 mV are required to drive the current density of 10 mA cm−2 with the small Tafel slope of 77.30 and 153.50 mV dec−1 for HER and OER, respectively. The Co–MoS2@NG-4 demonstrates excellent stability, maintaining a robust operation for 5000 cyclic tests with no detectable stability decay.