Synergistic Coupling of Charge Extraction and Sinking in Cu5FeS4/Ni3S2@NF for Photoassisted Electrocatalytic Oxygen Evolution

Thein-situ-formed Cu5FeS4/Ni3S2@NF catalyst exhibits efficient photoassistedelectrocatalytic oxygen evolution via synergistic coupling of chargeextraction and sinking. Exploringlow-cost and high-performance oxygen evolution reaction(OER) catalysts has attracted great attention due to their crucialrole in water splitting. Here, a bifunctional Cu5FeS4/Ni3S2@NF catalyst was in situ formedon a nickel (Ni) foam toward efficient photoassisted electrocatalytic(P-EC) OER, which displays an ultralow overpotential of 260 mV at30 mA cm(-2) in alkaline solution, outperforming mostpreviously reported Ni-based catalysts. It also shows great potentialin degradation of antibiotics as an alternative anode reaction toOER owing to the prompt transfer of photogenerated holes. The photocurrenttest and transient photovoltage spectroscopy indicate that the synergisticcoupling of charge extraction and sinking effects in Cu5FeS4 and Ni3S2 is critical for boostingthe OER activity via photoassistance. Electrochemical active surfacearea and electrochemical impedance spectroscopy tests further provethat the photogenerated electromotive force can effectively compensatethe overpotential of OER. This work not only provides a good guidancefor integrating photocatalysis and electrocatalysis, but also indicatesthe key role of synergistic extraction and utilization of photogeneratedcharge carriers in P-EC.