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[Display omitted] • HA was efficiently mineralized in an Fe0-Fe y C z /Fe x -GZIF-8-rGO aqueous suspension. • The polar alkane-alcohol complex was formed with more single electrons on –OH group. • The polar alkane-alcohol complex enhanced its surface cleavage and •OH formation. • The reaction kinetics depends on the surface complex characteristic. Natural organic matter (NOM) has diverse negative impacts on water purification, however, preventing them occurrence very difficult. Herein, humic acid (10 mg/L), as the main component of NOM, is completely destructed within 120 min in the Fe0-Fe y C z /Fe x -GZIF-8-rGO air-saturated aqueous suspension without additional energy input, while its mineralization is followed by three kinetic constants within 480 min. During the process, HA was first complexed with Fe0-Fe y C z /Fe x -GZIF-8-rGO by π-π interaction and H-bonding interaction and cleaved to aromatic compounds and then to alkanes and alcohols with some small acids before 120 min. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations confirmed that a strongly polarized alkane-alcohol complex was formed after 150 min with an electron-rich hydroxyl group area in alcohol and an electron-poor alkane area. Moreover, the more electrons of alkane in the complex are delocalized and trapped by O 2 , with the adsorption of the alkane-alcohol complex on the catalyst surface based on the analyses of both electrochemical impedance spectroscopy (EIS) and chronoamperometry, greatly promoting the surface cleavage and hydrolytic process of alkane in the complex and producing more •OH for pollutant degradation than it does from the HA surface complex, which results in the highest mineralization rate in the period of 150–390 min. Our findings demonstrated that the current system is very promising for complex mixture-containing water purification without additional energy. [ABSTRACT FROM AUTHOR]

[Display omitted] The heterogeneous Fenton process suffers from low efficiency because of the low electron transfer cycle rate of Fe3+/Fe2+, which often consumes enormous amounts of hydrogen peroxide (H 2 O 2) or other energy. Herein, we report a novel Co-based Fenton-like catalyst (in-situ -Co-g-C 3 N 4) synthesized via the surface complexation method, in which Co species were modified in situ into the framework of the graphitic carbon nitride (g-C 3 N 4) substrate through C–O–Co chemical bonding. The catalyst exhibited higher Fenton-like catalytic activity than pure g-C 3 N 4 in the degradation of various pollutants under neutral conditions, as evidenced by the approximately 150-fold higher Fenton-like reaction rate constant of in-situ -Co-g-C 3 N 4 than that of g-C 3 N 4. Density functional theory (DFT) calculations and a series of experimental and characterization analyses revealed the interfacial reaction mechanism between H 2 O 2 , pollutants and in-situ -Co-g-C 3 N 4. During the Fenton-like reaction, the electron-poor C center on the aromatic ring of g-C 3 N 4 could capture the electrons deprived from pollutants, and subsequently deliver them to around the electron-rich Co center to efficiently reduce H 2 O 2 to hydroxyl radicals (•OH), enabling H 2 O 2 to be used efficiently for the degradation of pollutants. This study provides a strategy for improving Fenton-like degradation efficiency by effectively utilizing the energy of organic pollutants. [ABSTRACT FROM AUTHOR]

The catalytic activity of H 2 O 2 dissociation and formation on zinc chalcogenides was determined by the surface micro-engineering construction including surface orientation and heteroatomic doping. [Display omitted] • The activity of ZnX depends on the surface orientation and heteroatoms. • H 2 O 2 can dissociate to form •OH on ZnO(1 1 0), ZnSe(1 0 0), ZnTe(1 1 0) and ZnTe(1 0 0). • ZnO (1 1 0) surface can catalyze water oxidation to form H 2 O 2. • The selectivity of water oxidation to form H 2 O 2 can be enhanced by doping. • A descriptor was derived from the valence electrons and electronegativity. Establishing the structure–activity relationship is very important for the design of new catalysts for advanced oxidation process with low energy consumption and high efficiency. In this work, the atomic mechanism of hydrogen peroxide (H 2 O 2) dissociation and formation on zinc chalcogenides (ZnX, where X denotes O, S, Se, and Te) was investigated. It was found that the catalytic activity of H 2 O 2 dissociation and formation on ZnX was determined by the surface micro-engineering construction including surface orientation and heteroatomic doping. H 2 O 2 can dissociate to easily form hydroxyl radicals on ZnO (1 1 0), ZnSe (1 0 0), ZnTe (1 1 0) and ZnTe (1 0 0) surfaces, while only the ZnO (1 1 0) surface can catalyze water oxidation to form H 2 O 2. Furthermore, the H 2 O 2 selectivity of water oxidation on the ZnO (1 1 0) surface can be enhanced by the doping with silver atoms due to the weak adsorption strength of OH*, while introducing copper atom into the ZnO (1 1 0) surface can promote H 2 O 2 dissociation. These results not only unveil the mechanism of H 2 O 2 dissociation and formation on ZnX, but also can provide helpful guidance for the development of new catalytic oxidation systems. [ABSTRACT FROM AUTHOR]

d-g-C 3 N 4 -Fe composites was prepared via a self-assembly and calcination process. According to measurements and density functional theory (DFT) computations, the complexation of iron and pyridinic N of g-C 3 N 4 (Fe‒N) occurred with Fe(III)-π interaction, causing more oxygen vacancies (OVs) with more electrons in iron oxides. In the catalyst air-saturated suspension, the adsorbed pollutants complexed surface Fe(III) through their hydroxyl group donated electrons to around OVs, reducing the surface Fe(III) to Fe(II) and were destructed by Fe(III)-π interaction of the complexation. The addition of H 2 O 2 mainly acted as acceptor being reduced •OH at the OV centers, causing higher degradation rate of pollutants due to both •OH and the surface reaction. However, for the adsorbed hydrophobic pollutants onto the sites of peripheral structure in g-C 3 N 4 , H 2 O 2 was mainly decomposed into O 2 by the synergistic effect of iron species and OVs. Therefore, the catalyst exhibited high Fenton-like efficiency for the degradation of hydroxyl-containing pollutants and hydrophobic pollutants mixing with the former. Our results demonstrate that the Fe(III)-π interaction could carry out the oxidation of pollutants on the catalyst surface, decreasing the consumption of H 2 O 2 , and the role of OVs depends on pollutant adsorption patterns. ga1 • Fe‒N complexation formed between g-C 3 N 4 and iron oxide in d-g-C 3 N 4 -Fe. • More oxygen vacancies produced in iron oxide of d-g-C 3 N 4 -Fe. • Degradation of organics was performed from the surface oxidation rather than •OH. • d-g-C 3 N 4 -Fe shows excellent activity for hydroxyl-containing pollutants degradation. • Efficiency of H 2 O 2 depended on the synergistic effect of OVs and pollutant adsorption. [ABSTRACT FROM AUTHOR]

• N-doped porous carbon was prepared via transformation from graphitic carbon nitride. • N-doped porous carbon (NC 1.0) possesses ultrahigh N content up to 33.75 at%. • NC 1.0 exhibits excellent reactivity and stability for peroxymonosulfate activation. • DFT calculations reveal PMS activation involving PMS reduction and oxidation. • Singlet oxygen (1O 2) is the main reactive oxygen species in the NC 1.0 /PMS system. Nitrogen-doped carbon materials are proposed as promising metal-free catalysts for persulfate-mediated catalytic oxidation process, yet the nitrogen content in the final carbon products is typically low. Moreover, controversies remain in the unambiguous identification of active sites in nitrogen-doped carbons for persulfate activation. Here we report the facile synthesis of nitrogen-doped carbon material via one-step pyrolysis of urea and D-mannitol, which simultaneously combine ultrahigh nitrogen content (up to 33.75 at%) with apparent porous structure via transformation from graphitic carbon nitride. With this strategy, the highly nitrogen-doped porous carbon (NC 1.0) exhibits excellent catalytic activity toward peroxymonosulfate (PMS) activation for oxidation of organic pollutants. Both experiments and density functional theory (DFT) calculations, for the first time, revealed that the electron-rich graphitic N and electron-deficient carbon atom adjacent to graphitic N in NC 1.0 served as active sites for PMS reduction and oxidation toward the generation of hydroxyl radical (OH) and singlet oxygen (1O 2), respectively, in which PMS oxidation was the main reaction in the course of PMS activation rendering 1O 2 the dominant reactive oxygen species (ROS) in the NC 1.0 /PMS system. More importantly, NC 1.0 presents robust stability in PMS activation, superior to most reported nitrogen-doped carbon-based catalysts, offering great promise for practical environmental remediation. [ABSTRACT FROM AUTHOR]