Designed formation of CuS 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, CuS photoelectrodes composed of hierarchical nanostructures were synthesised on copper foam (CF) by varying thiourea concentrations (10-120 mg) to modulate the CuS hierarchical nanostructures and then optimise the photoelectrochemical performance. The results show that the CF@CuS-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) at 10 mA cm, 50.61% (from 980 to 1476 mF cm) at 20 mA cm, and 58.82% (from 918 to 1458 mF cm) at 30 mA cm. Over 5000 cycles, the specific capacitance remains stable, with an initial areal capacitance of 550 mF cm in the dark and a 22.73% enhancement (675 mF cm) under illumination with a single wavelength of 365 nm. These findings underscore the significance of thiourea concentration in optimizing the properties of CuS and enhancing its photo-assisted electrochemical performance for self-charging PSCs.