Density Functional Theory Calculations for Insight into the Heterocatalyst Reactivity and Mechanism in Persulfate-Based Advanced Oxidation Reactions

Abstract

Advanced oxidation processes (AOPs) based on persulfates such as peroxymonosulfate and peroxydisulfate via heterogeneous catalysts have been a research hotspot due to their outstanding performances in removing emerging organic contaminants (OCs). In this Review, we highlight the recent advances in theoretical simulations for persulfate-based AOPs (PS-AOPs) using density functional theory (DFT), with the emphasis on the catalyst properties and the mechanism of persulfate activation over a variety of heterogeneous catalysts (including nanocarbons, metals, and metal oxides). Moreover, the properties of OCs and their degradation mechanism by diverse reactive oxygen species investigated by theoretical computations are also summarized. The descriptors in computational studies and the related structure−performance relationships are discussed. Finally, the challenges and future research focuses of DFT simulations in PS-AOPs are proposed, including the evaluation of catalyst properties, elucidation of the persulfate activation mechanism, especially the nonradical pathway, and the rational design of on-demand catalysts.

Toward Selective Oxidation of Contaminants in Aqueous Systems

“…222 These factors are inherently determined by the surface chemistry of the catalysts, which could be tuned via introduction of heteroatoms and structural defects, and/or facet engineering. 227,228 For examples, the sp 2 -hybridized carbon materials featuring delocalized π network are more reactive for adsorption and electron conductivity than the sp 3hybridized and amorphous carbons. 227 Shao et al found that structural double-vacancies in multiwalled carbon nanotubes (MWCNTs) would induce charge polarization and decrease the HOMO−LUMO gap of MWCNTs, resulting in the intensification of PMS adsorption and the electron transfer from target pollutants to PMS.…”

“…222 N doping could also change the charge distribution of the conjugated carbon network to benefit the interfacial electron transfer process. 228 nitrogenation, where the reduction of PDS occurred at the electron-rich pyridinic and pyrrolic N sites, whereas the oxidation of pollutants occurred at the electron-deficient atoms. 229 Generally, graphitic N is critical to initiate the electron transfer process, but different results available on this topic suggest further elucidation is still required.…”

Functional Carbon Nitride Materials in Photo‐Fenton‐Like Catalysis for Environmental Remediation

“…State‐of‐the‐art in situ characterization techniques and theoretical calculations can be used as tools to reveal the potential reaction intermediates, structure‐performance relationship, and catalytic mechanism. [ 220 ] The photo‐Fenton reaction, especially for the system with in situ H 2 O 2 generation, involves complex reaction pathways with multiactivated species: O 2 •− can be produced from the one‐electron reduction of O 2 ; • OH can be generated from the activation of self‐produced H 2 O 2 ; photoexcited holes can be separated and transferred to the surface of catalyst for the direct oxidation of pollutants. Therefore, for in‐depth understanding of the reaction mechanism, it is essential to distinguish the specific roles of different activated species.…”

Structure–Function Correlations of Carbonaceous Materials for Persulfate-Based Advanced Oxidation

“…The intrinsic and external characteristics of carbonaceous materials (Figure ), including dimensionality, pristine carbon configuration, crystallinity and defects, porosity, chemical active groups, and heterogeneous doping, affect the PS activation and thus the degradation of organic pollutants. It is noteworthy that the characteristics of the carbocatalyst mentioned above also determine the radical pathway, nonradical pathway, and adsorption and cleavage of pollutants …”

“…It is noteworthy that the characteristics of the carbocatalyst mentioned above also determine the radical pathway, nonradical pathway, and adsorption and cleavage of pollutants. 13 2.1. Dimensionality.…”