CoFe-Layered Double Hydroxide Needles on MoS₂/Ni₃S₂ Nanoarrays for Applications as Catalysts for Hydrogen Evolution and Oxidation of Organic Chemicals

Electrochemical water splitting prompted by organic molecules presents a competitive prospect for implementing energy-efficient hydrogen evolution and alleviating organic-rich water pollution. In this work, we fabricated a heterojunction of CoFe-layered double hydroxide (CoFe LDH) needles on MoS2/Ni3S2/nickel foam (NF) nanoarrays (CoFe LDH/MoS2/Ni3S2/NF) by forming a Schottky interface and a p–p heterojunction interface. The prepared CoFe LDH/MoS2/Ni3S2/NF exhibits superior electrocatalytic activities with low potentials to drive 50 mA cm–2 for the hydrogen evolution reaction (HER, 0.098 V vs the reversible hydrogen electrode (RHE)), oxygen evolution reaction (OER, 1.507 V vs RHE), urea oxidation reaction (UOR, 1.460 V vs RHE), and ethanol oxidation reaction (ETOR, 1.484 V vs RHE). Meanwhile, the electrode can maintain robust stability in these reactions. The enhanced electrocatalytic activities result from the increased active sites and the acceleration of charge transfer caused by the built-in electric fields. Moreover, the prepared catalyst also exhibits remarkable catalytic performance in two-electrode electrocatalytic systems of KOH, KOH assisted by urea, and KOH assisted by polylactic acid. This work offers a rational method for designing efficient electrocatalysts via combining heterojunctions to effectively generate hydrogen energy and treat organic pollutants.