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

The heterojunction photoelectrode with dual-component photosensitive Cu 2 O and pseudocapacitive NiCo 2 O 4 demonstrates light irradiation-enhanced energy storage performance. • The self-standing NiCo 2 O 4 /Cu 2 O heterogeneous photoelectrode is designed. • The photoelectrode demonstrates enhanced energy storage with light radiation. • The band structure between the NiCo 2 O 4 and Cu 2 O is studied by DFT. • The electron transfer path in NiCo 2 O 4 /Cu 2 O heterojunction is established. • The photo-assisted SC device possesses high energy density of 105.38 Wh kg −1 . 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 NiCo 2 O 4 /Cu 2 O photoelectrode with dual-component pseudocapacitive NiCo 2 O 4 and photosensitive Cu 2 O 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 NiCo 2 O 4 as well as the light-sensitive copper source, which significantly simplifies the preparation process of the photoelectrode. The NiCo 2 O 4 /Cu 2 O 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 NiCo 2 O 4 /Cu 2 O heterojunction, which contributes to a deeper understanding of the mechanism of photo-assisted supercapacitors.