(Fe, Ni)S2@MoS2/NiS2 hollow heterostructure nanocubes for high-performance alkaline water electrolysis.

Hollow hybrid heterostructures are regarded to be promising materials as bifunctional electrocatalysts for highly efficient water electrolysis due to their intriguing morphological features and remarkable electrochemical properties. Herein, with FeNi-PBA as both a precursor and morphological template, we demonstrate the rational construct of cost-effective (Fe,Ni)S 2 @MoS 2 /NiS 2 hollow hybrid heterostructures as bifunctional electrocatalysts for alkaline overall water splitting. Microstructural analysis shows that the hybrid is a kind of hierarchical heterostructure composed of MoS 2 /NiS 2 nanosheets/nanoparticles in situ grown on hollow (Fe,Ni)S 2 nanocubes with abundant heterointerfaces, which effectively maximizes the electrochemical active sites to the accessible electrolyte ions, leading to the promoted charge transfer. As expected, the hybrid shows remarkable alkaline electrocatalytic performance, such as hydrogen evolution overpotential of 176 mV and oxygen evolution overpotential of 342 mV at 50 mA cm−2, as well a cell voltage of 1.65 V at 20 mA cm−2. Moreover, the stability and durability are greatly enhanced under harsh electrochemical conditions. This study opens a new venue for developing earth-abundant bifunctional electrocatalysts with hollow hybrid heterostructures for alkaline water electrolysis in the future. (Fe, Ni)S 2 @MoS 2 /NiS 2 hollow hybrid heterostructures achieved with FeNi-PBA as both a precursor and morphological template by the facile and conventional strategies, were reported as active and stable bifunctional electrocatalyst for alkaline water electrolysis. Benefitted from the maximized exposure of catalytic active edges of MoS 2 nanosheets and NiS 2 nanoparticles (the outer shell) and the enhanced electrical conductivity of (Fe,Ni)S 2 (the inner core), as well as the hollow hybrid heterostructures facilitating rapid electrolyte diffusion, the hybrid exhibited remarkable alkaline electrocatalytic activity with HER overpotential of 91 mV at 10 mA cm−2 and OER overpotential of 275 mV at 20 mA cm−2. A low cell voltage of 1.65 V at 20 mA cm−2 was required for water electrolysis with satisfactory durability after continuous operation for 20 h. [Display omitted] • (Fe, Ni)S 2 @MoS 2 /NiS 2 hollow nanocubes derived from FeNi PBA were obtained. • The hybrid presents abundant heterointerfaces with maximizing active sites. • The inner hollow (Fe,Ni)S 2 nanocubes facilitate electrolyte ion diffusion. • Superior catalytic activity for HER (η 50 = 176 mV) and OER (η 50 = 342 mV) is achieved. • The stability and durability are greatly enhanced under harsh electrochemical conditions. [ABSTRACT FROM AUTHOR]