Improvement on electrochemiluminescence properties of graphite carbon nitride by metal oxidation state regulation

Reasonable design is of great significance for improving the performance of electrochemiluminescence (ECL) co-reactant accelerators. The different d-band structure of metal single atoms will produce different oxidation states, which may change the adsorption of reaction intermediates to the catalyst and affect its catalytic activity. In this study, we have demonstrated that the ECL performances of graphite carbon nitride (CN) can be promoted by modulating the metal oxidation states of co-reaction accelerator for the first time. The oxidation states of Au were modulated by the different electronic metal–support interaction (EMSI) between the co-reaction accelerator (Au single atoms, Au nanoparticles [Au NPs]) and CN, and the effects of Au oxidation states on the ECL performances of CN were investigated. Comparison to pristine CN and CN nanosheets supported Au nanoparticles (Au NPs/CN), stronger and more stable ECL intensity of CN nanosheets supported Au single-atoms (Au^S/CN) was obtained. The ECL signal of Au^S/CN was about 32.2 times that of the original CN, and 2.8 times that of Au NPs/CN in the same Au loading content (0.8%). Detailed mechanism revealed that Au^S/CN with higher Au oxidation state has better conductivity and stronger catalytic activity, which promotes the electric reduction of CN and S₂O₈²⁻, increases the lifetime of the excited state CN*, and significantly improves the ECL performance of CN. In addition, this work provides a detailed understanding of the essence of EMSI for the ECL intensity amplification and established a feasible method for the improvement of ECL capacities of co-reactant accelerators.