In-situ thermal reduction synthesis of porous carbon nitride doped gadolinium sulfide nanocomposite: An emerging electrode material for high-performance supercapacitor

The multiple-step synthesis, harmful organic solvents, and hazardous binders are the major obstacles for supercapacitor (SC) designers. A conventional synthesis of nanocomposite is normally involves complex steps and time-consuming. To reduce these multiple steps and process time, we report carbon nitride-doped gadolinium sulfide (CN/Gd₂S₃) nanocomposite obtained via a one-step in situ thermal reduction method. In our study, we introduce poly(3,4-ethylenedioxythiophenes): polystyrene sulfonate (PEDOT–PSS) to act as a dual role of binder and conducting additive, and we use DI water as the solvent for the SC electrode. Despite the reduced fabrication steps, our electrode exhibits an extraordinary specific capacity value of 1831 F g⁻¹ at 1 A g⁻¹ in an aqueous 2 M KOH electrolyte, as well as 98.5 % retention after 5000 cycles. Moreover, a solid-state asymmetric SC (ASC) was further made up with activated carbon (AC) as a negative electrode and CN/Gd₂S₃ as a positive electrode, providing a high energy density of 70.95 W h kg⁻¹ at a specific power density of 250 W kg⁻¹ at 1 A g⁻¹. The remarkable specific capacitance retention of the ASC could maintain 86.8 % after 5000 cycles, indicating the potential application of CN/Gd₂S₃ electrode material for energy storage devices. This device (CN/Gd₂S₃//AC) showcased its practical application by powering twenty-six light-emitting diodes (LEDs) (each of 2.7 V) and appeared as an attractive energy storage unit for portable devices.