Synergistic Coupling of Charge Extraction and Sinking in Cu 5 FeS 4 /Ni 3 S 2 @NF for Photoassisted Electrocatalytic Oxygen Evolution.

Exploring low-cost and high-performance oxygen evolution reaction (OER) catalysts has attracted great attention due to their crucial role in water splitting. Here, a bifunctional Cu 5 FeS 4 /Ni 3 S 2 @NF catalyst was in situ formed on a nickel (Ni) foam toward efficient photoassisted electrocatalytic (P-EC) OER, which displays an ultralow overpotential of 260 mV at 30 mA cm -2 in alkaline solution, outperforming most previously reported Ni-based catalysts. It also shows great potential in degradation of antibiotics as an alternative anode reaction to OER owing to the prompt transfer of photogenerated holes. The photocurrent test and transient photovoltage spectroscopy indicate that the synergistic coupling of charge extraction and sinking effects in Cu 5 FeS 4 and Ni 3 S 2 is critical for boosting the OER activity via photoassistance. Electrochemical active surface area and electrochemical impedance spectroscopy tests further prove that the photogenerated electromotive force can effectively compensate the overpotential of OER. This work not only provides a good guidance for integrating photocatalysis and electrocatalysis, but also indicates the key role of synergistic extraction and utilization of photogenerated charge carriers in P-EC.