Ti ₃ C ₂ T _X NR-Accelerated Electron Transfer and Electron–Hole Recombination Boost Electrochemiluminescence in Gold Nanoclusters

Although electrochemiluminescence (ECL) systems utilizing gold nanoclusters (AuNCs) as luminophores have been widely employed in sensing applications in recent years, the luminescence efficiency of AuNCs remains constrained by their low electronic conductivity and relatively slow electron-hole (e^--h⁺) recombination rate. Moreover, current research efforts predominantly concentrate on enhancing the ECL efficiency of AuNCs solely from either the excitation or emission perspective. Herein, we propose a strategy to enhance the ECL performance of AuNCs from both excitation and emission perspectives via compositing with Ti₃C₂T_X MXene nanoribbons (Ti₃C₂T_XNR). On one hand, the high conductivity of Ti₃C₂T_XNR reduces the electron transfer resistance at the electrode-electrolyte interface, thereby facilitating more rapid electron transfer during the oxidation of AuNCs in the excitation stage and providing more AuNCs radicals for the subsequent emission process. On the other hand, the novel composite luminophore AuNCs@Ti₃C₂T_XNR exhibits fewer deep surface electron trap states, which promotes the release of captured e^- and enhances the electron utilization efficiency in the ECL process, thereby improving the efficiency of e^--h⁺ recombination in the emission stage. Ultimately, based on the dual-enhanced ECL system, an ECL aptasensor was developed for the detection of estradiol. This strategy with excitation-emission dual enhancement exhibits great development potential in the fields of nanomaterial performance improvement and sensor analytical capability enhancement.