DFT Calculation of Nonperiodic Small Molecular Systems to Predict the Reaction Mechanism of Advanced Oxidation Processes: Challenges and Perspectives

Advanced oxidation processes (AOPs) have a broad rangeof potentialapplications in the treatment of emerging refractory emerging pollutants.However, due to the presence of highly reactive substances such asfree radicals that are difficult to capture, it is challenging toinvestigate the mechanism of AOPs at the elementary reaction level.The conventional methods, such as electron spin resonance (ESR), freeradical quantification, and free radical quenching, are plagued bysystematic issues that have led to bottlenecks in the field of AOPstudies. The development of computational chemistry theory and computerperformance provides a new method to study the mechanism of AOPs throughdensity functional theory (DFT) calculation. Due to its excellentcost-performance benefit, DFT calculations for aperiodic smallmolecules have become popular in the field of AOPs. In this paper,a comprehensive review is presented on the applications of DFT calculationsfor predicting active sites and exploring reaction selectivity andoxidant activation mechanisms. A systematic classification of methodsrelated to molecular descriptors and transition states is provided.Furthermore, some current research issues are identified, and futuredevelopment prospects and challenges are discussed.

Automated summary

Advanced oxidation processes (AOPs) have diverse applications in treating refractory pollutants, but the investigation of AOP mechanisms at the elementary reaction level is challenging due to the presence of elusive free radicals. Conventional methods have limitations, thus computational chemistry theory, particularly density functional theory (DFT) calculation, provides a promising alternative. This review focuses on the applications of DFT calculations in predicting active sites, exploring reaction selectivity, and understanding oxidant activation mechanisms in AOPs.