Quantitative isotope measurements in heterogeneous photocatalysis and electrocatalysis

Heterogeneous photocatalysis and electrocatalysis have attracted tremendous interest in energy chemistry including CO2 reduction, N2 fixation, water oxidation, oxygen reduction, organic transformations, etc. The molecular-level understanding of reaction mechanisms in photocatalysis and electrocatalysis is pivotal to facilitate these processes, and the quantitative isotope measurement provides such a toolbox. Herein, we summarize the theory of two kinds of important isotope measurements (i.e., kinetic isotope effect and isotope labeling methods) and then review their important applications in photocatalytic/electrocatalytic CO2 reduction, N2 fixation, water oxidation, oxygen reduction and organic transformations on heterogeneous catalysts. Future prospects for quantitative isotope measurements are also presented.