Exploring of SnS/Nb₄C₃(GQDs) as electrode materials for energy storage devices performance evaluation and development opportunities and hydrogen evolution reactions

In response to the increasing need for energy, supercapacitors developed to store an additional energy level and exhibit superior efficiency in accumulating energy compared to traditional batteries that undergo several charge–discharge cycles. Transition metal carbides/nitrides, known as MXenes (Nb₄C₃ MXene), have been the primary subject of advanced research by scientists in energy storage. MXenes, a promising class of 2D materials, offer a unique combination of high conductivity, hydrophilicity, tunable surface chemistry, mechanical resilience, and outstanding electrochemical properties, making them ideal candidates for electrode applications. The recently developed pseudocapacitive material optimizes electrochemical energy storage through its abundant interlayer ion diffusion channels and ion storage sites. Moreover, the MXene has some low conductivity issues; to overcome these issues, the Nb₄C₃ MXene structure was decorated with Tin monosulfide (SnS). Furthermore, the GQDs were introduced as 6 wt.% dopants to improve the additional conductivity level. The alterations above lead to enhanced porosity, surface area, density, particle structure, shape, and size. These features substantially contribute to improving the electrochemical process (energy storage and hydrogen evaluation reaction). The resulting SnS/Nb₃C₄(GQDs)-fabricated electrode displayed an excellent specific capacity of 300 C/g and maintained significant charge–discharge cycle stability; capacity retention and coulombic efficiency are 95.52 and 98.61% over 12,000 cycles. The resulting symmetric device achieved a high E_d of 68.2 Wh/kg and Pd of 1315 W/kg at a current density of 2 A/g. Moreover, the SnS/Nb₃C₄(GQDs) electrode demonstrated a significantly lower HER overpotential of 88.7 mV and Tafel slope values of 83.7 mV/dec. The proposed approach offers a hydrothermal method to combine electrochemically active metal sulfide-based and 2D nanostructured materials, enhancing their energy storage and conversion performance. After the stability test, we have performed the CV, GCD and EIS analyses which show the optimal performance with minor change (Fig. S1).