Self-standing photo-assisted NiCo2O4/Cu2O electrode with boosted energy storage performance by an ultra-simple approach

Abstract

With the efficient use of sustainable sunlight, the development of the novel photo-assisted supercapacitor electrode is a practical method to improve energy storage performance by sunlight irradiation. Herein, the new type of self-standing NiCo₂O₄/Cu₂O photoelectrode with dual-component pseudocapacitive NiCo₂O₄ and photosensitive Cu₂O are successfully synthesized on copper foam via an ultra-simple approach. Intriguingly, the copper foam substrate is ingeniously designed to serve as the growth skeleton for the formation of NiCo₂O₄ as well as the light-sensitive copper source, which significantly simplifies the preparation process of the photoelectrode. The NiCo₂O₄/Cu₂O photo-assisted electrode demonstrates markedly high specific capacitance of 7.16F cm⁻² at 1 mA cm⁻² under light irradiation (the light intensity is 100 mW cm⁻²), which far exceeds those of conventional similar active materials. A maximum energy density of 105.38 Wh kg⁻¹ at power density of 1.86kW kg⁻¹ is demonstrated by the photo-assisted supercapacitor under light. More importantly, this work builds the energy band structure by DFT calculations and the electron transfer path in NiCo₂O₄/Cu₂O heterojunction, which contributes to a deeper understanding of the mechanism of photo-assisted supercapacitors.