Rational Design of a Copper Cobalt Sulfide/Tungsten Disulfide Heterostructure for Excellent Overall Water Splitting

Integratingdifferent components into a heterostructure is a novelapproach that increases the number of active centers to enhance thecatalytic activities of a catalyst. This study uses an efficient,facile hydrothermal strategy to synthesize a unique heterostructureof copper cobalt sulfide and tungsten disulfide (CuCo2S4-WS2) nanowires on a Ni foam (NF) substrate.The nanowire arrays (CuCo2S4-WS2/NF) with multiple integrated active sites exhibit small overpotentialsof 202 (299) and 240 (320) mV for HER and OER at 20 (50) mA cm(-2) and 1.54 V (10 mA cm(-2)) for anelectrolyzer in 1.0 M KOH, surpassing commercial and previously reportedcatalysts. A solar electrolyzer composed of CuCo2S4-WS2 bifunctional electrodes also producedsignificant amounts of hydrogen through a water splitting process.The remarkable performance is accredited to the extended electroactivesurface area, reasonable density of states near the Fermi level, optimaladsorption free energies, and good charge transfer ability, furthervalidating the excellent dual function of CuCo2S4-WS2/NF in electrochemical water splitting.