Qualitative and quantitative electrochemiluminescence evaluation of trace Pt single-atom in MXenes

The analysis of trace Pt single-atom (SA) represents a significant challenge, given the crucial role of single-atom platinum (Pt) in energy storage and electrocatalysis. Here, we present an electrochemiluminescence (ECL) platform that enables the qualitative and quantitative analysis of trace Pt SA using luminol as the ECL luminophore. It is observed that different Pt species in Ti_3-xC₂T_y MXenes resulted in distinct reactive oxygen species (ROS) potentials for luminol cathodic electrochemiluminescence (ECL), achieved through distinctive oxygen reduction reaction (ORR) pathways, in which oxygen acts as the co-reactant. Furthermore, the cathodic luminol ECL intensity increases in proportion to the Pt atom content, thereby enabling quantitative analysis of trace Pt single atoms. The detection limit is 0.014 wt%, which is comparable to the current mainstream Pt SA quantification techniques. By utilizing this ECL method, it is possible to successfully evaluate both qualitatively and quantitatively the changes in Pt SA during the ORR processes. This ECL platform provides a valuable toolbox for the analysis of Pt SA catalysts and for the evaluation of the mechanisms involved in electrocatalysis applications.