Photo-enhanced supercapacitive behaviour of photoactive Cu2FeSnS4 (CFTS) nanoparticles

We present here the synthesis of three different types of Cu2FeSnS4 (CFTS) nanoparticles with the help of solvothermal route. Different chain length of ethylene glycol (EG) (PEG-200, PEG-400 and PEG-600) were used as solvent in hydrothermal process which resulted in stannite phase CFTS nanoparticles which was confirmed by XRD analysis and other characterizations including Raman, SEM, TEM and XPS. Photoresponse of these as-prepared CFTS nanoparticles were studied and among them PEG-400 sample exhibited higher photoresponse and further electrochemical studies such as, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) were done. The as-prepared CFTS nanoparticles not only exhibit a significant enhancement in the electrochemical activity but also in the photo-enhanced specific capacitance under light irradiation. The CFTS nanoparticles were sulfurized at 500 degrees C to study the effect of sulfurization on photoresponse and photo-supercapacitive behaviour. Moreover, the sample synthesized with PEG-400 demonstrates an outstanding photoresponse among the three samples. The sulfurized CFTS exhibited less specific capacitance compared to the as-prepared sample probably due to the formation of some secondary phases. This study opens up for the direct utilization of this light harvesting CFTS nanoparticles for solar cell and exhibited high photon induced specific capacitance for supercapacitor application.