Bifunctional NiCuOx photoelectrodes to promote pseudocapacitive charge storage by in situ photocharging

Charging electrochemical devices by light irradiation may bring an essential change in energy-storage technologies. Herein, nickel copper mixed oxide (NiCuOx)-based bifunctional photoelectrodes for integrated energy conversion and storage were developed to achieve significant capacitance enhancements by a photocharging process. NiCuOx nanosheets have been directly grown on carbon cloth (CC) by a simple electrodeposition/annealing method. NiO/CuOx heterojunctions have been formed in the CC@NiCuOx nanosheet structures, which presented an intimate interfacial contact, endowing the materials with bifunctional properties for realizing photoenergy conversion and electrochemical charge storage simultaneously. When used as three-electrode supercapacitors, the as-prepared CC@NiCuOx photoelectrodes demonstrated a maximum specific capacitance of 2937 mF cm(-2) under light irradiation, corresponding to 17.5% of enhancement compared to those delivered without light irradiation. Such a significant enhancement could be contributed by the in situ photocharging process, where the photo-generated holes from CuOx (including CuO and Cu2O) were transferred to neighboring NiO and then promoted the oxidation reactions of NiO. This work has provided a tentative study to show how photo-generated charge carriers can promote electrochemical charge storage.

Automated summary

Charging electrochemical devices by light irradiation can result in significant capacitance enhancements, thereby potentially revolutionizing energy-storage technologies.