Ti₃C₂T_X-Protected CsPbBr₃ Perovskite Quantum Dot Architecture for Enhanced Charge Transport in Hydrogen Evolution and Supercapacitor Applications

Hydrogen generated via electrochemical water splitting is a sustainable energy carrier, however, sluggish hydrogen evolution reaction (HER) kinetics necessitate efficient, low-cost alternatives to Pt-based catalysts. In this regard, CsPbBr₃ perovskite and Ti₃C₂T_X MXene offer complementary advantages, CsPbBr₃ provides tunable ionic-electronic conductivity and a narrow band gap, while Ti₃C₂T_X ensures high metallic conductivity, abundant surface terminations, and structural robustness. A hierarchical CsPbBr₃@Ti₃C₂T_X nanohybrid synthesized via an in situ hot-injection method achieved strong interfacial coupling, where -OH, -O, and -F terminations of MXene enhanced charge redistribution and electron mobility, stabilizing CsPbBr₃ PQDs and preventing aggregation. This engineered interface promoted efficient charge transfer, maximizing active site utilization. The hybrid exhibited remarkable HER performance with a low onset potential (-231.12 mV) and a Tafel slope of 48.04 mV·dec^-1, following the Volmer-Heyrovsky mechanism, along with superior stability and favourable hydrogen adsorption energy. Additionally, it delivered a high specific capacitance and excellent cycling durability, underscoring its multifunctional energy potential.