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Graphical abstract Highlights • Mo S C and Mo O Co electron transfer bridges are successfully constructed on CMS-rGO NSs. • CMS-rGO NSs possesses the function of generating and activating H 2 O 2 synchronously. • CMS-rGO NSs shows very high Fenton-like activity for degradation of pollutants. • Dye pollutants can directly act as electron donors for CMS-rGO NSs. Abstract Consumption of additional H 2 O 2 is necessary in classical Fenton catalysis. Herein, we report a novel and special nanocatalyst consisting of CoMoS 2 nanosphere-embedded, reduced graphene oxide (rGO) nanosheets (CMS-rGO NSs). This nanocatalyst was discovered to have an impressive reactivity for in situ generation and synchronistical activation of H 2 O 2 in different active centers, yielding fast and efficient degradation of the pollutants. The reaction rate is ∼21 times higher than that of conventional Fenton catalysts. The characterization shows that countless flower-like CoMoS 2 nanospheres are uniformly embedded in the rGO nanosheets through Mo S C bonding bridges in CMS-rGO NSs, which leads to activation of the π electrons and their transfer from rGO to the metal centers (π → M). The formed Mo O Co further leads to a distribution of orientations of the electrons around the metal centers due to the different electronegativity of Mo and Co. During the reaction, the dissolved O 2 is efficiently reduced to HO 2 /O 2 − around the electron-rich Mo center, and HO 2 /O 2 − is further reduced to H 2 O 2 around the Co center. The generated H 2 O 2 is finally reduced to OH for degrading dyes in the electron-rich metal (Mo or Co) centers of CMS-rGO NSs. The dye pollutants also act as electron donors, and they are directly degraded in the electron-poor π-center of CMS-rGO NSs, which promote the electron transfer cycle and achieve electron gain-loss balance. This discovery provides a new strategy for H 2 O 2 generation-activation and pollutant degradation through constructing electron transfer bridges over the surface of catalysts. [ABSTRACT FROM AUTHOR]

BiOI is widely used as photocatalysts for pollutant removal, water splitting, CO 2 reduction and organic transformation due to its excellent photoelectric properties. Here, we report for the first time that a light-free catalyst consisting of the flower-like BiOI microspheres ( f -BiOI MSs) exposing (1 0 1) and (1 1 0) crystal planes prepared by a hydrothermal method in ethylene glycol environment can rapidly eliminate the refractory BPA within only ∼3 min through a Fenton-like process. The reaction activity is ∼190 times higher than that of the conventional Fenton catalyst Fe 2 O 3 . A series of characterizations and experiments reveal the formation of the dual reaction centers on f -BiOI MSs. The electron-rich O centers efficiently reduce H 2 O 2 to OH, while the electron-poor oxygen vacancies capture electrons from the adsorbed pollutants and divert them to the electron-rich area during the Fenton-like reactions. By these processes, pollutants are degraded and mineralized quickly in a wide pH range. Our findings address the problems of the classical Fenton reaction and are useful for the development of efficient Fenton-like catalysts through constructing dual reaction centers. [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, a novel metal-free catalyst consisting of multiporous oxygen-rich carbon–nitrogen graphene-like nanosheets (O LAA -CN NSs) is first developed through a staged temperature-programmed calcination of l -ascorbic acid (LAA)-modified dicyandiamide precursor. It is found that the oxygen species from l -ascorbic acid (O LAA) are introduced into the graphene-like basic matrix and replace partial N atoms to form the C O C-R structure, leading to the non-uniform distribution of electrons on the catalyst surface, and the formation of electron-rich centers around the C O C microareas according to a series of characterization techniques. As a result, O LAA -CN NSs exhibits excellent performance for refractory pollutant removal in the presence of peroxymonosulfate (PMS) and dissolved oxygen. Some pollutants with complex structures are even completely degraded within only 1 min. The interface reaction mechanism is further revealed that PMS mainly acts as an active inducer to drive the electron donation of pollutants over O LAA -CN NSs. These electrons are finally utilized by dissolved oxygen to generate reactive oxygen species (ROS) through the interface process. This reaction system results in pollutants that can either be cleaved directly by surface oxidation process or degraded by the attack of the generated ROS, such as singlet oxygen (1O 2) and superoxide radicals (O 2 •−), through oxygen activation, which significantly reduces the resource and energy consumption in advanced wastewater treatment by harnessing the energy of pollutants and dissolved oxygen in the water. [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]

• Mesoporous reduction state cobalt species-doped silica nanospheres are first prepared. • Excellent activity is realized in mp -RSCo-SiO 2 NSs/H 2 O 2 system. • Efficient dual-pathway degradation of pollutant is achieved in Fenton-like process. • Pollutants replace H 2 O 2 as electron donors for the mp -RSCo-SiO 2 NSs system. • A new interfacial Fenton-like reaction mechanism involving pollutants is proposed. A novel heterogeneous Co-containing Fenton-like catalyst consisting of mesoporous reduction state cobalt (RSCo)-doped silica (SiO 2) nanospheres (mp -RSCo-SiO 2 NSs) was prepared by an enhanced hydrothermal process. The catalyst exhibited very high activity and stability for a series of refractory pollutant degradation in a very wide pH range of 3.1–10.9. The Fenton-like reaction rate constant of this Co-containing catalyst was approximately 290 times higher than that of Co 3 O 4 for pollutant degradation under the neutral and mild conditions. Based on the characterization, the catalyst possessed a porous nanosphere morphology, and the reduction state cobalt species, including nano-zero-valent cobalt (nZVCo) and Co2+, were found to be generated in the SiO 2 framework through forming Co O Si bonds. During the Fenton-like reaction, the electron donation effect of organic pollutants was successfully realized through the interaction of "Pollutants → Co2+/0-SiO 2 ". The obtained electrons from pollutants were transferred to the catalyst surface and captured by H 2 O 2 , resulting in the generation of hydroxyl radicals (OH). Therefore, a dual-pathway degradation of the pollutants was realized: (I) oxidation and degradation as the electron donors for the system and (II) attacking and destruction by OH radicals. This work provided a new perspective on the effective utilization of the electrons of pollutants and the improvement of Fenton reaction efficiency. [ABSTRACT FROM AUTHOR]