Sulfur‐Induced Interface Engineering of Hybrid NiCo2O4@NiMo2S4 Structure for Overall Water Splitting and Flexible Hybrid Energy Storage

Abstract To rationally design hybrid structures with unique surface/interface features is very significant due to their multi‐functionalization in energy storage and conversion systems. Generally, single metal oxide as electrode material is still unsatisfactory for its slow electron transportation and inevitable structural collapse. To address these issues, sulfur element‐induced interface‐tailoring hybrid NiCo 2 O 4 @NiMo 2 S 4 nanosheet structures with high electrochemical activity are reported through a simple vulcanization process of NiCo 2 O 4 @NiMoO 4 nanosheets. The hybrid NiCo 2 O 4 @NiMo 2 S 4 structure presents excellent hydrogen evolution reaction performance with the overpotential of 159 mV at 10 mA cm −2 and low Tafel slope of 53.1 mV dec −1 , and overall water splitting abilities with low cell voltage of 1.63 V at 50 mA cm −2 and stability for 13 h. As supercapacitor electrode materials, the hybrid structures exhibit a specific capacitance 519 C g −1 at 1 A g −1 , which is higher than that of hybrid NiCo 2 O 4 @NiMoO 4 nanosheets (420 C g −1 ). The asymmetric device delivers an energy density of 30.73 Wh kg −1 at a power density of 374.9 W kg −1 .