Pt on Carbon Quantum Dot–TiO2–Ti3C2T x Heterostructures for Enhanced Photocatalytic Fast Green Dye Degradation and the Hydrogen Evolution Reaction

Abstract

The development of multifunctional catalysts with efficient charge-transfer characteristics is crucial for advancing photocatalytic wastewater remediation and electrochemical hydrogen production. In the present work, a Pt-decorated Carbon Quantum Dots (CQD)–TiO2–MXene (Pt/CTM) heterostructure was successfully synthesized through a combined hydrothermal and chemical reduction approach. The catalyst consists of uniformly dispersed Pt nanoparticles (∼2.87 nm) anchored on delaminated Ti3C2Tx MXene nanosheets, creating multidimensional nanoscale heterointerfaces that promote rapid interfacial charge transfer and abundant catalytically active sites. Structural and microscopic analyses confirmed the successful formation of a multidimensional heterointerface with uniformly dispersed Pt nanoparticles over the conductive CTM framework. X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and synchrotron-based X-ray absorption spectroscopy (XAS) revealed strong electronic interaction between Pt and CTM, resulting in electron transfer from CTM to Pt, reduced work function, modified Pt 5d electronic structure, and abundant low-coordinated Pt active sites. The Pt/CTM catalyst exhibited excellent electrocatalytic hydrogen evolution reaction (HER) activity in 0.5 M H2SO4, delivering a low overpotential of 158 mV at 100 mA cm–2 with a small Tafel slope of 25.85 mV dec–1 and excellent long-term stability. Simultaneously, the Pt/CTM photocatalyst demonstrated outstanding photocatalytic activity toward Fast Green dye degradation, achieving nearly complete degradation (∼100%) within 20 min under UV irradiation. The enhanced catalytic performance was attributed to efficient charge separation, rapid interfacial electron transfer through the MXene/CQD network, and Schottky junction formation at the Pt–CTM interface. This study establishes a direct structure–electronic property–activity relationship and highlights the importance of electronic-structure engineering for designing advanced MXene-based multifunctional catalytic heterostructures.