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Nitrate (NO3-) pollution control and resource recovery are important for water remediation and the sustainable production of value-added nitrogen chemicals. However, electrocatalytic nitrate reduction involves complex multielectron transfer processes, in which reactant adsorption, intermediate evolution, and interfacial mass transport collectively influence catalytic kinetics. Conventional ensemble-averaged measurements often obscure these dynamic interfacial processes at individual catalyst particles. To address this challenge, the research team developed an operando electrochemiluminescence (ECL) microscopy strategy that converts nitrate adsorption and the evolution of the key nitrite intermediate into visual and quantitative optical signals, thereby linking interfacial nitrate reduction processes with apparent catalytic kinetics at the single-particle level.
By exploiting the distinct effects of nitrate and nitrite on ECL signals, the researchers established two quantitative descriptors, termed the "decay ratio" and "decay time", to characterize interfacial NO3- adsorption and the dynamic evolution of the key intermediate NO2-, respectively. These descriptors further allowed spatial mapping of apparent kinetics and turnover frequency (TOF) at the single-particle level. The study revealed kinetic heterogeneity of Cu nanosheets at the single-particle level and further demonstrated the influence of intermediate diffusion and interparticle coupling on apparent catalytic kinetics. Under dilute nitrate conditions, the apparent catalytic kinetics were found to depend not only on local catalytic activity but also on reactant enrichment, intermediate accumulation, and interfacial mass transport. By transforming dynamic interfacial processes, including NO3- adsorption, NO2- evolution, and interparticle coupling, into visual and quantitative spatiotemporal information, this work provides a new operando imaging approach for elucidating complex electrocatalytic interfaces and their contributions to apparent catalytic kinetics.
This research, titled "Operando electrochemiluminescence imaging of intermediate evolution and kinetics in electrocatalytic nitrate reduction" was published in the prestigious academic journal Nature Communications (article link: https://www.nature.com/articles/s41467-026-77519-8). The team’s PhD student, Zhichen Zhang, is the first author of the paper, with Cheng Ma (Yangzhou University), and Professor Wenlei Zhu serving as corresponding authors. The study was supported by the National Natural Science Foundation of China, the Jiangsu Young Talent Lifting Project, Fundamental Research Funds for the Central Universities, State Key Laboratory of Water Pollution Control and Green Resource Recycling and State Key Laboratory of Analytical Chemistry for Life Science.
