Flexible photo-assisted supercapacitor utilizing ternary Mn-Ni-Co sulfides on titania electrodes

In this study, we present our photoelectrochemical investigations of a ternary metal sulfide thin film of manganese nickel cobalt sulfide (MNCS) electrodeposited on titanium dioxide nanotubes grown on flexible titanium substrates (MNCST). The resulting MNCST photoelectrodes exhibit excellent photoelectrochemical properties and exceptional energy storage capacity. The optimal MNCST4 photoelectrode exhibited an areal-specific capacitance of 4846 mF/cm2 at a current density of 1 mA/cm2 under light, which is 56 % higher than its capacitance in the dark. All fabricated supercapacitors exhibited higher specific capacitances when illuminated compared to those tested without light. Of the five supercapacitors produced, the MNCST4@MNCS/ITO device exhibited the highest specific capacitance, excellent cycling stability (90.6 % retention after 10,000 cycles), and good flexibility. In the absence of light, the device had an areal capacitance of 617 mF/cm2. However, when exposed to light, the areal capacitance increased significantly to 789 mF/cm2, which corresponds to an impressive increase of 127.9 % at a current density of 1 mA/cm2. Remarkably, the device generated a photovoltage of 594 mV within 700 s, eliminating the need for an external power supply. In addition, the device showed excellent electrochemical performance under illumination conditions with an areal energy density of 4551 mWh/cm2.