Flexible multi-layered porous CuxO/NiO (x = 1, 2) photo-assisted electrodes for hybrid supercapacitors: Design and mechanism insight

With the utilization of sustainable sunlight efficiently, it is of paramount important to develop a new type of electrode for boosting photo-assisted supercapacitor performance. Herein, this work originally designs the Ni35Cu15Zr15Ti35 metallic glass (MG) ribbon as dealloying precursor. Benefiting from the different oxidation behavior of Ni and Cu metals during the dealloying and anodizing processes, a new type of multi-layered porous hybrid photoelectrode (namely CuxO/np-NiCu@NiCuO/MG, x = 1, 2) that simultaneously achieve the flexible, hierarchical porous structure as well as the NiO/Cu2O heterojunction, are successfully synthesized. An intriguing multi-layered structure consists of the outermost photosensitive CuxO nanowire layer formed by the anodizing technique, the nanoporous NiCu@NiCuO layer just beneath the nanowire layer via the dealloying as well as the glass central layer offering an excellent flexibility. In particular, 3D interconnected hierarchical porous structure is benefit to the penetration and utilization of visible light efficiently. The photoelectrode demonstrates a maximum specific capacitance of 1182.2 F cm−3 with light irradiation, which is 18% higher than that without light. This photo-assisting charging for the supercapacitor is ascribed to the combination of photosensitive CuxO and pseudocapacitive NiO components. Moreover, the photoelectrode exhibits an excellent flexibility and the photocurrent response is basically unchanged after bending for 1000 times. The aqueous supercapacitor shows a maximum energy density of 44.9 mWh cm−3 under light. This work provides new insights into the development of next generation wearable photo-assisted supercapacitor.