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A low-consumption water purification system is firstly constructed based on a new dual-reaction-center (DRC) catalyst molybdenum-doped zinc sulfide (Mo-ZnS, MZS) with a confined nonequilibrium surface. The extremely strong electron trapping ability of the Mo site is realized by the substitution of Mo for ZnS lattice. In this way, the electrons of emerging contaminants (ECs) are efficiently transferred to the nonequilibrium surface through the oriented interface process (Mo-S-Zn bond bridge), and obtained by the natural dissolved oxygen (DO) to generate hydrogen peroxide (H 2 O 2) under trace H 2 O 2 trigger without light and electricity assistant. The highest yield of H 2 O 2 is even up to ∼230 % of the initial value, and the ECs removal can reach 100 % within 60 min, which is far superior to conventional Fenton catalysts. This work realized the efficient utilization of the contaminant electrons through the construction of Mo-S-Zn bond bridge, which greatly reduced the energy consumption of water purification and improved the resourcefulness of ECs. [Display omitted] • DRC catalyst MZS with the confined nonequilibrium surface is first prepared. • MZS shows excellent performance for water purification. • Efficient H 2 O 2 generation is achieved without light and electricity assistant. • The highest H 2 O 2 concentration reaches up to ∼230 % of the initial concentration. • ECs electrons are efficiently utilized in ORR processes and water purification. [ABSTRACT FROM AUTHOR]

• The Fenton-like Cu-PAN 3 catalysts is first synthesized by co-precipitation and carbon thermal reduction method. • Dual reaction centers are constructed around graphene-like carbon and Cu species. • The pollutants as electron donors inhibit the ineffective decomposition of H 2 O 2 at the electron-poor centers. • The pollutant removal mainly relies on the surface cleavage at the electron-poor centers. High energy consumption has seriously hindered the development of Fenton-like reactions for the removal of refractory organic pollutants in water. To solve this problem, we designed a novel Fenton-like catalyst (Cu-PAN 3) by coprecipitation and carbon thermal reduction. The catalyst exhibits excellent Fenton-like catalytic activity and stability for the degradation of various pollutants with low H 2 O 2 consumption. The experimental results indicate that the dual reaction centers (DRCs) are composed of Cu-N-C and Cu-O-C bridges between copper and graphene-like carbon, which form electron-poor/rich centers on the catalyst surface. H 2 O 2 is mainly reduced at electron-rich Cu centers to free radicals for pollutant degradation. Meanwhile, pollutants can be oxidized by donating electrons to the electron-poor C centers of the catalyst, which inhibits the ineffective decomposition of H 2 O 2 at the electron-poor centers. This therefore significantly reduces the consumption of H 2 O 2 and reduces energy consumption. [Display omitted] [ABSTRACT FROM AUTHOR]

• A highly crystalline BiOBr (c-BiOBr) is synthesized by a two-step process. • A high crystallinity of c-BiOBr enhances the interaction of pollutant and [Bi 2 O 2 ]2+. • The adsorbed pollutant on c-BiOBr plays a role of molecular modification. • The molecular modification effect facilitates the direct pollutant oxidation. • The active electron transfer from pollutant promotes the generation of more O 2 •–. The adsorption of pollutants can not only promote the direct surface reaction, but also modify the catalyst itself to improve its photoelectric characteristics, which is rarely studied for water treatment with inorganic photocatalyst. A highly crystalline BiOBr (c-BiOBr) was synthesized by a two-step preparation process. Owing to the calcination, the highly crystalline enhanced the interface interaction between pollutant and c-BiOBr. The complex of organic pollutant and [Bi 2 O 2 ]2+ could promote the active electron transfer from the adsorbed pollutant to c-BiOBr for the direct pollutant degradation by holes (h+). Moreover, the pollutant adsorption actually modified c-BiOBr and promoted more unpaired electrons, which would coupling with the photoexcitation to promote generate more O 2 •–. The molecular modification effect derived from pollutant adsorption significantly improved the removal of pollutants. This work strongly deepens the understanding of the molecular modification effect from the pollutant adsorption and develops a novel and efficient approach for water treatment. [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]

In common advanced oxidation processes, excess reagents and energy are often added to the reaction system to maintain the continuity of the reaction. These additions result in a large waste of resources and energy, which has become a bottleneck in the development of water treatment technology. In this study, we propose a new strategy to solve this problem based on a novel dual-reaction-center (DRC) Fe-ZnS quantum dots (Fe–ZnS QDs) catalyst that forms a non-equilibrium surface with an electron-polarized distribution. Through experimental and theoretical studies, it was verified that the activation of trace amounts of H 2 O 2 could break the energy barrier for pollutants to transfer electrons. The dissolved oxygen (DO) in the reaction system could be activated by gaining energy on the surface of the Fe–ZnS QDs catalyst, and was converted to 1O 2 to attack organic pollution. In addition, the pollutants themselves supplied electrons to H 2 O 2 through the surface of the Fe–ZnS QDs catalyst to generate more •OH radicals for pollutant degradation, thus providing two fast paths for pollutant degradation. The system could drive the reaction through a trace amount of H 2 O 2 , thereby activating DO to generate 1O 2 while effectively using the energy of pollutants. Therefore, the proposed system offers a new direction for the development of environmentally-friendly catalysts and greatly reduces the consumption of resources and energy. [Display omitted] • Fe–ZnS QDs is successfully developed as a Fenton catalyst for the first time. • The surface of ZnS QDs is regulated by trace Fe to form a non-equilibrium surface with an electron-polarized distribution. • The Fe–ZnS QDs/H 2 O 2 system exhibits excellent activity for pollutants degradation. • Inert oxygen species in reaction system are easily activated to 1O 2 to attack 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]

[Display omitted] • Single-atom Fe, Co, and Cu on the supports with similar properties are synthesized. • Single-atom catalysts were efficient in degradation of the pollutants. • The durability of single-atom metal is in an order of Co − N 4 ≈ Fe − N 4 ≫ Cu − N 4. • Co(IV) = O was evidenced to be contribute predominantly to pollutant degradation. Single-atom metal catalyzed peroxymonosulfate (PMS) activation shows great potential in water treatment; and the activity of various metal centers have been explored. The properties of the support contribute significantly to the catalytic performance of the metal centers. The knowledge on the intrinsic distinctions of the elements in single-atom catalyzed PMS activation is, however, relatively in lack. In this work, via a facile one-step method, three representative elements of Fe, Co, and Cu were configured in a metal − N 4 structure and anchored on N-doped carbon matrix with similar composition and structure. The atomic dispersity of the metal centers was experimentally substantiated by electronic microscopic technique in atomic scale and X-ray absorption spectroscopy. All these single-atom metal centers exhibit high activity in PMS activation for selective degradation of the organic pollutants, while the durability of the single-atom metal centers is vastly distinct as examined in continuous flow-mode. The water treatment capacity is in an order of Co − N 4 ≈ Fe − N 4 ≫ Cu − N 4 for the elimination of 0.1 mM 4-chlorophenol from water. Based on the analysis of the qunching effect by various probe molecules and electron spin resonance spectra at various reaction conditions, the high-valent Co(IV) O species is proposed to be the predominant active species for pollutant degradation in Co − N 4 catalyzed PMS activation. The findings in this work sheds light on the desgin of efficent and durable single-atom catalyst for water treatment. [ABSTRACT FROM AUTHOR]

Single-atom Fe catalysis has exhibited remarkable potentials in water treatment applications. However, rational design of single-atom Fe catalysts with controlled catalytic performance is still challenging, due to the lack of the fundamental understanding on the corelated factors of structure, property, and catalytic behavior. Herein, PMS activation performance of the single-atom Fe sites is successfully boosted by molecular-engineering on the polymeric carbon nitride (CN) framework. Benzene-1,4-diamine regulates the polymerization process, and rises the ratio of carbon/nitrogen; the valence of the single-atom Fe is thereby positively shifted, leading to favorable thermal dynamics of the high-valent Fe(IV)=O involved oxidation reaction. The carbon-rich CN supported single-atom Fe catalyst thus exhibits remarkable performance in selective degradation of a series of organic pollutants via high-valent Fe(IV)=O oxidation pathway. The findings in this work implicate the significance of electronic properties of the support as one of the essential descriptors for a robust single-atom catalyst for pollutants abatement. [Display omitted] • Benzene diamine in precursor for synthesis of single-atom Fe catalyst could positively shift the valence of Fe center. • A 5.1 times of performance improvement in bisphenol A degradation reaction was realized. • The single atom Fe catalyst with optimized valence is durable in a fixed-bed reactor. • Theoretical simulation states that positive valence of Fe center lowered the energy barrier of the catalytic reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zero-added conversion of chicken manure into water treatment catalyst (RCM) is realized. • Electron-poor/rich microregions are successfully constructed on RCM. • Pollutant degradation processes can be driven by a little bit of peroxymonosulfate. • RCM has excellent performance on actual wastewater treatment. • Water treatment with low consumption is achieved by utilization of pollutants. Fecal pollution in rural areas and water pollution caused by emerging contaminants (ECs) are two international environmental problems. Here, we propose a new strategy to address the two problems simultaneously through the resource utilization and harmless transformation of poultry manure as a kind of water purification catalyst with zero addition. The ordered bonding of intrinsic metal-organic species is realized in the resourcelized procedure by a one-stage calcination-annealing method, which results in the formation of electron-rich/poor microregions. With the triggering of a small amount of peroxymonosulfate (PMS), the energy/electrons of ECs are utilized by the dissolved oxygen in water driven by the electron-rich/poor microregions on the catalyst surface. As a result, the system exhibits excellent performance in removing various ECs. The degradation rate can even be maintained above 94.3 % after 10,000 cycles. This work indicates a sustainable approach to the effective utilization and treatment of rural waste and pollutants. [ABSTRACT FROM AUTHOR]

A twofold cation-π-assembled catalyst consisting of honeycomb microsphere-like MoS 2 cross-linking g-C 3 N 4 hybrid (HM-MS/CN) is first developed to address the bottleneck of excessive resource and energy consumption in Fenton chemistry. A series of modern characterization techniques combined with theoretical calculation are used to reveal and verify the twofold cation-π interaction (Mo-O-C and Mo-S-C bonding bridges). It is found that the electrons of pollutants can be captured by H 2 O 2 and O 2 through the twofold cation-π interaction during Fenton-like reaction, which inhibits the oxidative decomposition of H 2 O 2 and promotes its hydroxylation. As a result, HM-MS/CN shows excellent performance for water purification by initiating pollutants as electron donors substituting H 2 O 2 consumption under mild natural conditions, and the actual consumption of H 2 O 2 in this system is only 6–8% of that in the common Fenton systems. This discovery is of great significance for the development of novel water purification technology with high efficiency and low consumption. [Display omitted] • A twofold cation-π-assembled catalyst consisting of HM-MS/CN is first prepared. • HM-MS/CN shows excellent performance for actual water purification. • The actual consumption of H 2 O 2 is only 6–8% of that in the common Fenton systems. • Twofold cation-π interaction based on Mo-O-C and Mo-S-C is responsible for excellent performance. • Pollutants act as electron donors substituting H 2 O 2 consumption via twofold cation-π. [ABSTRACT FROM AUTHOR]

• Co2+-N-C π is constructed via atomically dispersed Co bonding with C-based graphene-like structure. • Co2+-N-C π (Co−π) structure plays key role for PMS activation and pollutant degradation. • Electron donation effect of pollutants is realized through π-π interaction in SACo-NGs system. • High efficiency and low consumption are realized in SACo-NGs/PMS water treatment system. Orbital interaction involving metal cation−π is an important form for electron transfer regulation. To accelerate the interfacial electron transfer of peroxymonosulfate (PMS) activation for water treatment, we report a new strategy through bonding atomically dispersed cobalt with nanospheric C-based graphene-like structures (SACo-NGs) to form metal cation−π structure, driving rapid and directional transfer of the electrons of pollutants to PMS on the catalyst surface. The catalyst SACo-NGs is synthesized by an enhanced hydrothermal-sintering method and the formation of metal cation−π structure is demonstrated by X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR) and Raman spectroscopy. It is found that Co−π structures (Co2+-N-C π) play a key role for the efficient activation of PMS, which results in pollutants being greatly removed in a few minutes. During the reaction, pollutants can donate electrons for the system through π−π interaction accompanying by the direct oxidative degradation of pollutants. The obtained electrons are quickly transferred to the atomically dispersed cobalt sites through the formed cation−π structure, which promotes the activation of PMS. This is a successful practice in the field of PMS activation using cation−π structure to accelerate electron transfer and achieve rapid degradation of pollutants. [ABSTRACT FROM AUTHOR]

• Excellent activity for water purification is realized in cobalt-zinc ferrite/PMS system. • Surface oxygen vacancy induces PMS activation to generate •OH, SO 4 •− and H 2. • An efficient dual-pathway removal of pollutants is first achieved in PMS activation. • Pollutants replace PMS as electron donors for the V O -rich ZnFe 0.8 Co 0.4 O 2.4 system. • A novel solid-liquid interfacial reaction mechanism is proposed in PMS activation. Peroxymonosulfate (PMS) activation in heterogeneous processes for pollutant degradation is a promising water purification technology. However, the existed rate limiting step greatly restrains its performance and increases the consumption of PMS and energy. Herein, we offer a new strategy to solve this problem. In this work, surface oxygen vacancy (V O)-rich ZnFe 0.8 Co 0.4 O 2.4 nanoparticles were prepared and characterized, which exhibited high activity and stability for refractory pollutant degradation with PMS activation. It was found that PMS ([O 3 S O I O II H]−) could be adsorbed and trapped by the surface oxygen vacancies in the form of O I - Vo or O II - Vo during the reaction. Different electron transfer pathways from Vo to different O sites of PMS was realized in the solid-liquid interface based on the generation of OH, SO 4 − or H 2 from PMS reduction. Pollutants were predominantly adsorbed at metal Co sites in which their electrons were captured by metal species and then transferred to the surface oxygen vacancies, achieving efficient recycling of electrons in the aqueous suspensions. This system achieves a dual-pathway degradation of pollutants and electron transfer from pollutants to PMS to produce free radicals and H 2 , essentially changing the traditional concepts of pollutant removal and providing a sustainable strategy for pollutant utilization during water purification. [ABSTRACT FROM AUTHOR]