RESUMEN
Integrating different components into a heterostructure is a novel approach that increases the number of active centers to enhance the catalytic activities of a catalyst. This study uses an efficient, facile hydrothermal strategy to synthesize a unique heterostructure of 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 overpotentials of 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 an electrolyzer in 1.0 M KOH, surpassing commercial and previously reported catalysts. A solar electrolyzer composed of CuCo2S4-WS2 bifunctional electrodes also produced significant amounts of hydrogen through a water splitting process. The remarkable performance is accredited to the extended electroactive surface area, reasonable density of states near the Fermi level, optimal adsorption free energies, and good charge transfer ability, further validating the excellent dual function of CuCo2S4-WS2/NF in electrochemical water splitting.
RESUMEN
Electrocatalysts play an important role to increase the energy conversion efficiency of electrolysis processes. In this study, a heterostructure of zinc iron oxide (ZnFe2O4) and polyoxometalate (POM) nanoplates (POM-ZnFe2O4) was fabricated for the first time by a hydrothermal process. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) analysis of POM-ZnFe2O4 furnished low overpotentials of 268 and 356 mV, and 220 and 290 mV to achieve current densities of 20 and 50 mA cm-2, respectively. In addition, an electrolytic cell composed of a POM-ZnFe2O4 cathode and anode required an operating voltage of 1.53 V to deliver a current of 10 mA cm-2. The improved electrochemical performance of POM-ZnFe2O4 compared to commercial and recently reported catalysts is attributed to the high electrocatalytically active surface area, modulation in the electronic and chemical properties and the formation of heterojunction of ZnFe2O4 and POM, which are vital for accelerating HER and OER activity.