Designed formation of Cu ₂ S hierarchical nanostructures as self-supported photoelectrodes for photo-supercapacitors

Self-charged photo-supercapacitors (PSCs) have garnered significant attention due to their light chargeability, rapid charging capabilities, and compact design. In this study, Cu₂S photoelectrodes composed of hierarchical nanostructures were synthesised on copper foam (CF) by varying thiourea concentrations (10-120 mg) to modulate the Cu₂S hierarchical nanostructures and then optimise the photoelectrochemical performance. The results show that the CF@Cu₂S-100 photoelectrode exhibits the most significant photo-enhanced performance, with areal capacitance increasing under light illumination compared to the dark conditions by 32.98% (from 1140 to 1516 mF cm^-2) at 10 mA cm^-2, 50.61% (from 980 to 1476 mF cm^-2) at 20 mA cm^-2, and 58.82% (from 918 to 1458 mF cm^-2) at 30 mA cm^-2. Over 5000 cycles, the specific capacitance remains stable, with an initial areal capacitance of 550 mF cm^-2 in the dark and a 22.73% enhancement (675 mF cm^-2) under illumination with a single wavelength of 365 nm. These findings underscore the significance of thiourea concentration in optimizing the properties of Cu₂S and enhancing its photo-assisted electrochemical performance for self-charging PSCs.