Engineering Ti₃C₂T_X@rGO Heterostructures for Synergistic Hydrogen Evolution and Supercapacitive Energy Storage Applications

The escalating global energy demand and depletion of fossil fuels necessitate the development of clean and sustainable technologies. Hydrogen, a high-energy-density and zero-carbon fuel, can be efficiently generated via electrochemical water splitting; however, sluggish hydrogen evolution reaction (HER) kinetics demand cost-effective catalysts. Concurrently, supercapacitors are vital for stabilizing renewable energy systems. Two-dimensional MXenes, particularly Ti₃C₂T_X, exhibit excellent conductivity, hydrophilicity, and tunable surface chemistry but suffer from restacking and surface oxidation. Integrating Ti₃C₂T_X with reduced graphene oxide (rGO) overcomes these limitations by preventing aggregation, enhancing conductivity, and promoting active site exposure. The optimized Ti₃C₂T_X@rGO (90:10) heterostructure enables efficient charge transport through conductive rGO interlayers, yielding a high capacitance of 357 F g^-1 at 1 A g^-1 and an overpotential of 131 mV at 10 mA cm^-2 for HER with low Tafel slope and resistance. DFT+U calculations reveal a near-optimal ΔG_H* (-0.08 eV), confirming interfacial coupling-induced electronic modulation. This hierarchical hybrid exemplifies a multifunctional platform for high-performance energy conversion and storage applications.