Self-standing photo-assisted NiCo2O4/Cu2O electrode with boosted energy storage performance by an ultra-simple approach
Siwen Zhang, Yang Liu, Hao Wang, Xinhao Sun, Man Li, Chunling Qin, Zhifeng Wang, Huaijun Sun
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 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.