“Kill two birds with one stone” role of PTCA-COF: Enhanced electrochemiluminescence of Au nanoclusters via radiative transitions and electrochemical excitation for sensitive detection of cadmium ions

Au nanoclusters (AuNCs) have attracted significant attention in electrochemiluminescence (ECL) owing to their excellent luminescent properties; however, achieving high-efficient ECL remains a formidable challenge. Despite the extensively reported emphasis on enhancing radiative transitions, it is imperative to acknowledge that both radiation and excitation play crucial roles in ECL, thereby requiring a dual-enhanced strategy for improving ECL efficiency. Herein, we introduced PTCA-COF, a dual-functional covalent organic frameworks (COFs) with the effect of “kill two birds with one stone” to achieve this purpose. The PTCA-COF not only acted as a carrier to effectively suppress the rotational vibration of surface ligands and reduce self-quenching by minimizing non-radiative transitions, but also acted as an electrosensitiser that facilitated the generation of electrogenerated holes, thereby promoting efficient transfer of hot electrons and enhancing excitation of AuNCs due to favorable energy level alignment. As a proof of concept, by utilizing cadmium ions (Cd2+) as a model analyte, the ECL aptasensing platform fabricated based on the dual-enhancement AuNCs-COFs ECL system demonstrated a broad linear response spanning from 1 pM to 5 nM and achieved an impressive low detection limit of 0.66 pM (S/N=3) with exceptional reproducibility and selectivity. The findings of this study not only presented a novel approach for the rational dual-enhancement of ECL efficiency, but also contributed to the advancement of their potential applications in the field of environmental monitoring. •A dual-functional PTCA-COF was applied to improve the ECL of AuNCs.•Suppressing ligand rotation vibration of AuNCs enhanced emission efficiency.•Energy levels alignment between PTCA-COF and AuNCs improved excitation efficiency.•The developed ECL aptasensor showed excellent performances for Cd2+detection.