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Direct solar-to-hydrogen conversion from pure water using all-organic heterogeneous catalysts remains elusive. The challenges are twofold: (i) full-band low-frequent photons in the solar spectrum cannot be harnessed into a unified S1 excited state for water-splitting based on the common Kasha-allowed S0 → S1 excitation; (ii) the H+ → H2 evolution suffers the high overpotential on pristine organic surfaces. Here, we report an organic molecular crystal nanobelt through the self-assembly of spin-one open-shell perylene diimide diradical anions (:PDI2-) and their tautomeric spin-zero closed-shell quinoid isomers (PDI2-). The self-assembled :PDI2-/PDI2- crystal nanobelt alters the spin-dependent excitation evolution, leading to spin-allowed S0S1 → 1(TT) → T1 + T1 singlet fission under visible-light (420 nm~700 nm) and a spin-forbidden S0 → T1 transition under near-infrared (700 nm~1100 nm) within spin-hybrid chromophores. With a triplet-triplet annihilation upconversion, a newly formed S1 excited state on the diradical-quinoid hybrid induces the H+ reduction through a favorable hydrophilic diradical-mediated electron transfer, which enables simultaneous H2 and O2 production from pure water with an average apparent quantum yield over 1.5% under the visible to near-infrared solar spectrum. Achieving direct solar-to-hydrogen conversion from pure water using solely organic heterogeneous catalysts is still challenging. Here the authors report an all-organic semiconductor catalyst system for overall water splitting under visible to near-infrared light via triplet-triplet annihilation up conversion based on spin coupling. [ABSTRACT FROM AUTHOR]

During the discharge of Na–O2 batteries, O2 is reduced and combines with Na+ to form an insulating solid sodium oxide on the cathode, which severely hinders the mass transfer path, resulting in high polarization voltage, low energy efficiency, and short battery life. Hereby, we proposed a novel illumination-assisted Na–O2 battery in which bismuth vanadate (BiVO4) with few defects and high surface areas was used as the catalyst. It showed that the charge overpotential under photo assistance reduced by 1.11 V compared with that of the dark state one. Additionally, the insolating sodium oxide discharge products were completely decomposed, which was the key to running Na–O2 batteries over 200 cycles with a charge potential of no more than 3.65 V, while its counterpart (under dark condition) at 200 cycles had the charge potential higher than 4.25 V. The experiment combined with theoretical calculation shows that few defects, high surface areas, the altered electron transfer kinetics, and the low energy gap and low oxygen absorption energy of the (040) crystal face of monoclinic BiVO4 play an important role in catalyzing oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). [ABSTRACT FROM AUTHOR]

Mixotrophic bacteria provide a desirable alternative to the use of classical heterotrophic or chemolithoautotrophic bacteria in environmental technology, particularly under limiting nutrients conditions. Their bi-modal ability of adapting to inorganic or organic carbon feed and sulfur, nitrogen, or even heavy metal stress conditions are attractive features to achieve efficient bacterial activity and favorable operation conditions for the environmental detoxification or remediation of contaminated waste and wastewater. This review provides an overview on the state of the art and summarizes the metabolic traits of the most promising and emerging non-model mixotrophic bacteria for the environmental detoxification of contaminated wastewater and waste containing excess amounts of limiting nutrients. Although mixotrophic bacteria usually function with low organic carbon sources, the unusual capabilities of mixotrophic electroactive exoelectrogens and electrotrophs in bioelectrochemical systems and in microbial electrosynthesis for accelerating simultaneous metabolism of inorganic or organic C and N, S or heavy metals are reviewed. The identification of the mixotrophic properties of electroactive bacteria and their capability to drive mono- or bidirectional electron transfer processes are highly exciting and promising aspects. These aspects provide an appealing potential for unearthing new mixotrophic exoelectrogens and electrotrophs, and thus inspire the next generation of microbial electrochemical technology and mixotrophic bacterial metabolic engineering. Key points: • Mixotrophic bacteria efficiently and simultaneously remove C and N, S or heavy metals. • Exoelectrogens and electrotrophs accelerate metabolism of C and N, S or heavy metals. • New mixotrophic exoelectrogens and electrotrophs should be discovered and exploited. [ABSTRACT FROM AUTHOR]

Designing a semiconductor‐based heterostructure photocatalyst for achieving the efficient separation of photogenerated electron‐hole pairs is highly important for enhancing H2 releasing photocatalysis. Here, a new class of Ni1−xCoxSe2–C/ZnIn2S4 hierarchical nanocages with abundant and compact ZnIn2S4 nanosheets/Ni1−xCoxSe2C nanosheets 2D/2D hetero–interfaces, is designed and synthesized. The constructed heterostructure photocatalyst exposes rich hetero‐junctions, supplying the broad and short transfer paths for charge carriers. The close contacts of these two kinds of nanosheets induce a strong interaction between ZnIn2S4 and Ni1−xCoxSe2C, improving the separation and transfer of photo‐generated electron‐hole pairs. As a consequence, the distinctive Ni1−xCoxSe2C/ZnIn2S4 hierarchical nanocages without using additional noble‐metal cocatalysts, display remarkable H2‐relaesing photocatalytic activity with a rate of 5.10 mmol g−1 h−1 under visible light irradiation, which is 6.2 and 30 times higher than those of fresh ZnIn2S4 nanosheets and bare Ni1−xCoxSe2C nanocages, respectively. Spectroscopic characterizations and theory calculations reveal that the strong interaction between ZnIn2S4 and Ni1−xCoxSe2C 2D/2D hetero‐interfaces can powerfully promote the separation of photo‐generated charge carriers and the electrons transfer from ZnIn2S4 to Ni1−xCoxSe2C. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) is a pivotal element of electrochemical water splitting which is able to produce clean hydrogen as an alternative to fossil fuel. Developing efficient Pt‐based electrocatalysts for the HER to work at all pHs is highly desirable, however, still a significant challenge, especially in alkaline conditions due to sluggish water dissociation and OHad transfer. Here, a new strategy for making a class of amorphous WOx‐surface decorated PtNi@Pt dendritic nanowires (WOx‐PtNi@Pt DNWs) to achieve highly efficient pH‐universal HER electrocatalysis is reported. The as‐made WOx‐PtNi@Pt DNWs display superior HER performance with the overpotentials of 24, 5, and 22 mV in 0.1 m KOH, 0.1 m HClO4, and 0.5 m phosphate‐buffered saline, respectively, at a current density of 10 mA cm−2. The mass activity of WOx‐PtNi@Pt DNWs in alkaline conditions is 3.3 mA μgPt−1 at an overpotential of 70 mV, among the best in all the reported materials. Theoretical calculations confirm the introduction of WOx to the PtNi DNWs plays a pivotal role in promoting the efficient electron transfer for the alkaline and acidic HER. The activation of the PtNi region within the PtNiWO interface is achieved by the WOx induced strain effect, which guarantees the superior performance in the HER. [ABSTRACT FROM AUTHOR]

The photocatalytic behavior of the graphene oxide (GO) modified Fe(III)/peroxymonosulfate (Fe/PMS) system for bisphenol A (BPA) degradation was investigated. With the addition of GO, a dramatic enhancement of BPA degradation was obtained at pH 3.0 under visible light irradiation. According to ESR analysis and quenching tests, both SO 4 - and OH are responsible for BPA degradation. The characterization analysis demonstrates that Fe(III) can chelate with the oxygenic functional groups on the surface of GO forming a stable GO-Fe(III) complex. The detections of different kinds of Fe species reveal that Fe(III) can be reduced to Fe(II) by GO via intramolecular electron transfer in the GO-Fe(III) complex, and visible light could enhance this process. The Fe(III)/Fe(II) cycle not only occurs on the surface of GO, but also in aqueous solution via homogeneous reactions. In addition, the degradation pathway of BPA was proposed based on the identification of the intermediates using GC–MS and LC-MS techniques. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of Mg and IAA on the photosystems of Al-stressed alfalfa (Medicago sativa L.). Alfalfa seedlings with or without apical buds were exposed to solutions fully mixed with 0 or 100 μM AlCl3 and 0 or 50 μM MgCl2 followed by foliar spray with water or IAA. Results from seedlings with apical buds showed that application of Mg and IAA either alone or combine greatly alleviated the Al-induced damage on photosystems. The values of photosynthetic rate (Pn), effective quantum yields [Y(I) and Y(II)] and electron transfer rates (ETRI and ETRII), proton motive force (pmf), cyclic electron flow (CEF), proton efflux rate (gH+), and activities of ATP synthase and PM H+-ATPase significantly increased, and proton gradient (ΔpH pmf) between lumen and stroma decreased under Al stress. After removing apical buds of seedlings, the Y(I), Y(II), ETRI, ETRII, pmf , and gH+ under exogenous spraying IAA significantly increased, and ΔpH pmf significantly decreased in Mg addition than Al treatment alone, but they were no significant difference under none spraying IAA. The interaction of Mg and IAA directly increased quantum yields and electron transfer rates, and decreased O2– accumulation in Al-stressed seedlings with or without apical buds. These results suggest that IAA involves in Mg alleviation of Al-induced photosystem damage via increasing pmf and PM H+-ATPase activity, and decreasing ΔpH pmf. [ABSTRACT FROM AUTHOR]

• The nZVW/H 2 O 2 system effectively degraded RhB. • The stepwise oxidation of nZVW can generate low valence tungsten species. • The corrosion of nZVW can produce H 2 O 2. • ·OH was produce via Fenton-like system between tungsten species and H 2 O 2. • RhB degradation pathways were proposed based on the variation of intermediates. Rhodamine B (RhB) removal in a tungsten species-catalyzed Fenton-like system using nanoscale zero valent tungsten (nZVW) was investigated. The nZVW system can effective remove RhB in oxygenated water, and the nZVW/H 2 O 2 system significantly enhances the RhB removal. Mechanism investigation shows that hydroxyl radical (·OH) is the primary reactive oxidant for removing RhB in both systems. The stepwise oxidation of nZVW can release reactive tungsten species and produce H 2 O 2 by electron transfer from W0 or low valent tungsten species to O 2 , and ·OH was then formed via a Fenton-like reaction between low valent tungsten species and H 2 O 2. The addition of H 2 O 2 in the nZVW/H 2 O 2 system can increase the RhB removal ratio by accelerating nZVW corrosion and enhancing the Fenton-like reaction. Moreover, higher pH inhibits the RhB removal due to the consumption of reactive tungsten species by OH−, and both higher nZVW and H 2 O 2 dosages can enhance the RhB removal. RhB degradation pathways in the nZVW/H 2 O 2 system are proposed involving N-de-ethylation, chromophore cleavage, ring open, and mineralization. In addition, the present study puts forward a new water treatment technique and contributes to understand the role of tungsten species in advanced oxidation processes. [ABSTRACT FROM AUTHOR]

• rGO exhibits excellent performance for enhancing PM oxidation. • Oxygen containing groups can provide electrons for activating PM. • Structural defects can mediate electron transfer between organics and PM. • Changeover between electron donor and mediator can be controlled by regulating active sites. Reports that the exploitation of metal-free carbon materials to enhance permanganate (PM) oxidation to abate organic pollution in water have emerged in recent publications. However, the activation mechanism and active sites involved are ambiguous because of the intricate physicochemical properties of carbon. In this study, reduced graphene oxide (rGO) as a typical carbon material exhibits excellent capability to boost permanganate oxidation for removing a wide array of organic contaminants. The simultaneous two reaction pathways in the rGO/PM system were justified: i) rGO donates to electrons to decompose PM and produce highly reactive intermediate Mn species for oxidizing organic contaminants; ii) rGO mediates electron transfer from organics to PM. Oxygen-containing groups (hydroxyl, carboxyl, and carbonyl) were justified as electron-donating groups, while structural defects (vacancy and edge defects) were shown to be critical for rGO-mediated electron transfer. Therefore, the oxidation pathway of the rGO/PM system can be controlled by regulating oxygen functional groups and structural defects. The changeover from electron donor to electron mediator by decorating surface active sites of carbon materials will be of great help to the design and application of carbocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Scandium oxide functionalized carbon nitride (5-ScO-CN) is successfully prepared. • A new approach to boost PMS based oxidation is proposed. • 5-ScO-CN mediate the photoexcited electron transfer between PMS and organic contaminants. • Sc 2 O 3 causes fast oxidation of organic contaminants and activation of PMS to produce radicals. • 5-ScO-CN exhibits high stability for multiple usage and the potential of practical application. Generation of reactive radicals via photocatalytic peroxymonosulfate (PMS) is restricted by the sluggish kinetics of PMS decomposition and lack of electron transfer channel. Herein, we firstly prepared rare earth oxide functionalized carbon nitride (5-ScO-CN) by simple in-situ one-step calcination method, and surprisingly found it mediated photoexcited electron transfer between PMS and organic contaminants to boost PMS based oxidation decontamination. Rare earth oxide proceeds as active sites to mediate electron transfer from organic contaminants and PMS under visible light irradiation, it concurrently elevates fast oxidation of organic contaminant and activation of PMS to produce reactive radicals to further oxidize organic contaminants. We conducted density functional theory (DFT) calculation and galvanic oxidation process (GOP) to further unveil the role of 5-ScO-CN for mediating photoexcited electron transfer and generation of reactive radicals. This work proposes a novel mechanism for visible light boosted PMS based oxidation and provides a novel strategy for application of photocatalytic oxidation in environmental remediation field. [ABSTRACT FROM AUTHOR]

Background: In acidic soils, aluminum (Al) competing with Zn results in Zn deficiency in plants. Zn is essential for auxin biosynthesis. Zn-mediated alleviation of Al toxicity has been rarely studied, the mechanism of Zn alleviation on Al-induced photoinhibition in photosystems remains unclear. The objective of this study was to investigate the effects of Zn and IAA on photosystems of Al-stressed alfalfa. Alfalfa seedlings with or without apical buds were exposed to 0 or100 μM AlCl3 combined with 0 or 50 μM ZnCl2, and then foliar spray with water or 6 mg L− 1 IAA. Results: Our results showed that Al stress significantly decreased plant growth rate, net photosynthetic rate (Pn), quantum yields and electron transfer rates of PSI and PSII. Exogenous application of Zn and IAA significantly alleviated the Al-induced negative effects on photosynthetic machinery, and an interaction of Zn and IAA played an important role in the alleviative effects. After removing apical buds of Al-stressed alfalfa seedlings, the values of pmf, gH+ and Y(II) under exogenous spraying IAA were significantly higher, and ΔpHpmf was significantly lower in Zn addition than Al treatment alone, but the changes did not occur under none spraying IAA. The interaction of Zn and IAA directly increased Y(I), Y(II), ETRI and ETRII, and decreased O2− content of Al-stressed seedlings. In addition, the transcriptome analysis showed that fourteen functionally noted genes classified into functional category of energy production and conversion were differentially expressed in leaves of alfalfa seedlings with and without apical buds. Conclusion: Our results suggest that the interaction of zinc and IAA alleviate aluminum-induced damage on photosystems via increasing pmf and decreasing ΔpHpmf between lumen and stroma. [ABSTRACT FROM AUTHOR]

• Coffee grounds as a carbon source, it's environmentally sustainable. • High tetracycline removal rate is due to 1O 2 and electron transfer. • Point defects and carbonyl groups were critical for 1O 2 and electron transfer. • N/S-codoped carbons may provide an advanced strategy for green wastewater treatment. Nitrogen and sulfur-codoped porous carbons (SNCs) with porous structures and high surface areas were successfully synthesized employing coffee grounds, sodium bicarbonate and L-cysteine monohydrochloride as precursors. The SNCs were highly efficient for adsorption and exhibited outstanding catalytic performance for the oxidative degradation of tetracycline hydrochloride (TeC) solutions, especially at a calcined temperature of 700 °C (SNCs-700). The radical quenching, advanced in situ electron paramagnetic resonance (EPR) technology, PS decomposition rates and Linear Sweep Voltammetry (LSV) indicated that the excellent oxidative effectiveness of the PS/SNCs-700 system originated from the nonradical pathways (singlet oxygen (1O 2) and electron transfer). It's supposed that N and S doping can effectively create point defects, which could generate 1O 2 , while carbonyl groups were determined to be the main active sites contributing to the electron transfer. TeC degradation intermediates were also identified, three degradation pathways, revealing that the pre-adsorption significantly accelerated the nonradical oxidation pathways. This approach provides an innovative method for the large-scale production and application of high-quality catalysts in water treatment. [ABSTRACT FROM AUTHOR]

• Fullerol strongly enhances Fe(III)/H 2 O 2 Fenton system to degrade DMP. • Fullerol promotes Fe(III)/Fe(II) cycles as electron donor and mediator. • Fe(III) combines with Fullerol to form Fe(III)-Fullerol complex. • Fe(III)-Fullerol complex produces Fe(II) via intramolecular electron transfer. • DMP degradation pathway were proposed involving three ways. Hydroxylated C 60 Fullerene (Fullerol) induced photochemical production of reactive oxygen species (ROS, e.g. singlet oxygen (1O 2) and hydroxyl radical (OH)) is a slow process, and the role of its surface groups other than high water-solubility is still lack of investigation. In this study, we demonstrate Fullerol can promote Fe(III)/Fe(II) cycles to degrade dimethyl phthalate (DMP) in Fe(III)/H 2 O 2 Fenton system as both an electron donor and an electron-transfer mediator. At acidic condition, the formation of carbonyl and carboxyl via pinacol rearrangement and subsequent keto-enol isomerization can produce cage-opened structure of Fullerol, resulting in the pH-dependent formation of Fe(III)-Fullerol complex. Two pathways of Fe(II) recovery via intramolecular electron transfer of Fe(III)-Fullerol complex to enhance Fe(III)/H 2 O 2 Fenton oxidation were proposed: 1) Fullerol direct reduces Fe(III) into Fe(II) as an electron donor in dark, and it was strongly enhanced under visible light irradiation; 2) Fullerol mediates electron transfer from electron donor (e.g. hydrogen peroxide and organics) to Fe(III) in visible light condition. Furthermore, DMP degradation pathway was proposed based on variation of main intermediates. [ABSTRACT FROM AUTHOR]

Magnetic field (MF, 200 mT) and Fe 3 O 4 (26 g/m2) are simultaneously employed to enhance acetate production from bicarbonate reduction in Serratia marcescens catalyzed cathode of microbial electrosynthesis system (MES), reaching 8.5 mM at an operational time of 9 d, higher than the controls by 1.7-time (Fe 3 O 4 only), 1.8-fold (MF only), and 2.3-time (neither Fe 3 O 4 nor MF). This confirms synergetic interaction of the MF and Fe 3 O 4 for enhanced acetate production in the MES. The presence of MF and Fe 3 O 4 induces the S. marcescens physiologically releasing more extracellular polymeric substances with a compositional diversity and containing more c -type cytochromes for facilitating extracellular electron transfer for efficient acetate production. Moreover, the favorable MF for less shedding (approximate 40%) of Fe 3 O 4 from the biocathode, also contributes to the efficient MES. This study provides a feasible strategy of the Fe 3 O 4 and MF for efficient acetate production from bicarbonate reduction in the MES. Image 1 • Synergetic interaction of magnetic field and loaded Fe 3 O 4 is observed in MES. • Magnetic field favors for less shedding of loaded Fe 3 O 4 from biocathode. • Magnetic field and Fe 3 O 4 regulate electrotrophic physiological activity. • Electrotroph releases EPS with a compositional diversity. • EPS contain c -type cytochromes for facilitating extracellular electron transfer. [ABSTRACT FROM AUTHOR]

The performance of four indigenous electrochemically active bacteria (EAB) ( Stenotrophomonas maltophilia JY1, Citrobacter sp. JY3, Pseudomonas aeruginosa JY5 and Stenotrophomonas sp. JY6) was evaluated for Cu(II) reduction on the cathodes of microbial fuel cells (MFCs). These EAB were isolated from well adapted mixed cultures on the MFC cathodes operated for Cu(II) reduction. The relationship between circuital current, Cu(II) reduction rate, and cellular electron transfer processes was investigated from a mechanistic point of view using X-ray photoelectron spectroscopy, scanning electronic microscopy coupled with energy dispersive X-ray spectrometry, linear sweep voltammetry and cyclic voltammetry. JY1 and JY5 exhibited a weak correlation between circuital current and Cu(II) reduction. A much stronger correlation was observed for JY3 followed by JY6, demonstrating the relationship between circuital current and Cu(II) reduction for these species. In the presence of electron transfer inhibitors (2,4-dinitrophenol or rotenone), significant inhibition on JY6 activity and a weak effect on JY1, JY3 and JY5 was observed, confirming a strong correlation between cellular electron transfer processes and either Cu(II) reduction or circuital current. This study provides evidence of the diverse functions played by these EAB, and adds to a deeper understanding of the capabilities exerted by diverse EAB associated with Cu(II) reduction. [ABSTRACT FROM AUTHOR]

• cMnO 2 can significantly promote Fe(VI) to oxidize various micropollutants. • High-valent Fe species were the primary active oxidants in the cMnO 2 −Fe(VI) system. • A novel surface-promoted mechanism was fully verified in the cMnO 2 −Fe(VI) system. • cMnO 2 showed outstanding catalytic stability in actual water. Current research focuses on introducing additional energy or reducing agents to directly accelerate the formation of Fe(IV) and Fe(V) from ferrate (Fe(VI)), thereby ameliorating the oxidation activity of Fe(VI). Interestingly, this study discovers that colloid manganese dioxide (cMnO 2) can remarkably promote Fe(VI) to remove various contaminants via a novel surface-promoted pathway. Many lines of evidence suggest that high-valent Fe species are the primary active oxidants in the cMnO 2 −Fe(VI) system, however, the underlying activation mechanism for the direct reduction of Fe(VI) by cMnO 2 to generate Fe(IV)/Fe(V) is eliminated. Further analysis found that Fe(VI) can combine with the vacancies in cMnO 2 to form precursor complex (cMnO 2 −Fe(VI)*), which possesses a higher oxidation potential than Fe(VI). This makes cMnO 2 −Fe(VI)* is more vigorous to oxidize pollutants with electron-rich moieties through the electron transfer step than alone Fe(VI), resulting in producing Fe(V) and Fe(IV). The products of Fe(VI) decay (i.e., Fe(II), Fe(III), and H 2 O 2) are revealed to play vital roles in further boosting the formation of Fe(IV) and Fe(V). Most importantly, the catalytic stability of cMnO 2 in complicated waters is superior to popular reductants, suggesting its outstanding application potential. Taken together, this work provides a full-scale insight into the surface-promoted mechanism in Fe(VI) oxidation process, thus providing an efficient and green strategy for Fe(VI) activation. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, the effects of ferric ion (Fe3+) on the degradation of atrazine (ATZ) in Bi 2 MoO 6 /peroxymonosulfate (PMS) system under visible light irradiation was investigated. With the addition of Fe3+, ATZ in the visible light/Bi 2 MoO 6 /PMS system degraded rapidly after 20 min treatment (removal rate > 99%). The enhancement of ATZ removal can be attributed to the role of Fe3+. As an electron transfer mediator, Fe3+ not only inhibits the recombination of photo-charges and prolongs the life of photogenerated carriers, but also promotes the activation of PMS by accelerating the electron transfer from Bi 2 MoO 6 to PMS. The generation of •OH and SO 4 •− in the system was determined via electron paramagnetic resonance (EPR) technology and quenching experiments. Furthermore, the characterization of Bi 2 MoO 6 before and after reaction, influence of the reaction parameters (i.e., catalyst and PMS dosages, Fe3+ and ATZ concentration, initial pH), influence of inorganic anions and humic acid, and the recyclability of catalyst in the vis/Bi 2 MoO 6 /PMS/Fe3+ system was also investigated. Additionally, the existence of Fe3+ also exhibits a wide selectivity for the degradation of different pollutants and high treatment efficiency. In general, the vis/Bi 2 MoO 6 /PMS/Fe3+ system demonstrated the potential as an efficient, economical, and environment-friendly water treatment process. [Display omitted] • Fe3+addition not only inhibits the recombination of the photo-charges, but also promotes PMS activation. • Fe3+ can activate PMS and capture photo-electron to enhance the photo-synergy for ATZ degradation. • •OH and SO 4 •− were the dominant species in the degradation of atrazine. • Bi 2 MoO 6 nanosheet showed excellent reusability and wide degradation selectivity in vis/Bi 2 MoO 6 /PMS/Fe3+ system. [ABSTRACT FROM AUTHOR]

Fenton oxidation technology is a widely-used advanced oxidation technology. However, the generation of hydroxyl radicals is restrained by the sluggish recovery of Fe(II), thus affecting its long-lasting performance for water decontamination. Here, a novel niobium carbide (Nb 2 C) MXene material was applied as a green co-catalyst. Nb 2 C MXene can significantly promote Fenton reactions to produce hydroxyl radicals for degrading dimethyl phthalate (DMP) with high efficiency and high stability for long-term operation, which outperforms than various reported co-catalysts. Meanwhile, the Nb 2 C/Fe(III)/H 2 O 2 system is capable of non-selectively degrading a wide spectrum of refractory pollutants. Mechanism investigation reveals that Nb 2 C MXene as an electron donor can straight reduce Fe(III), meanwhile mediate electron shuttle from Fe(II) to H 2 O 2 to strongly expedite the generation of hydroxyl radicals. In addition, four main degradation routes of DMP were proposed. Therefore, this study offers an updated and valid strategy for the refractory organic pollutants elimination by coupling Nb 2 C MXene and Fenton oxidation. [Display omitted] • Nb 2 C MXene outperformed than a variety of co-catalysts of enhanced Fenton system. • The Nb 2 C/Fe(III)/H 2 O 2 can non-selectively degrade a wide spectrum of organic contaminants. • Nb 2 C MXene can provide electrons for direct Fe(III) reduction by cleaving Nb-C bonds. • Nb 2 C MXene can mediate electron transfer between Fe(II) and H 2 O 2 to promote Fenton reaction. [ABSTRACT FROM AUTHOR]

Periodate (PI) has recently been studied as an excellent oxidant in advanced oxidation processes, and its reported mechanism is mainly the formation of reactive oxygen species (ROS). This work presents an efficient approach using N-doped iron-based porous carbon (Fe@N-C) to activate periodate for the degradation of sulfisoxazole (SIZ). Characterization results indicated the catalyst has high catalytic activity, stable structure, and high electron transfer activity. In terms of degradation mechanism, it is pointed out that the non-radical pathway is the dominant mechanism. In order to prove this mechanism, we have carried out scavenging experiments, electron paramagnetic resonance (EPR) analysis, salt bridge experiments and electrochemical experiments, which demonstrate the occurrence of mediated electron transfer mechanism. Fe@N-C could mediate the electron transfer from organic contaminant molecules to PI, thus improving the efficiency of PI utilization, rather than simply inducing the activation of PI through Fe@N-C. The overall results of this study provided a new understanding into the application of Fe@N-C activated PI in wastewater treatment. [Display omitted] • The activation of PI was successfully promoted with Fe@N-C. • The reaction mechanism of Fe@N-C/PI system is electron transfer mechanism. • The degradation pathway of pollutants in Fe@N-C/PI system was proposed. • No iodate and other harmful byproducts were produced during the reaction. [ABSTRACT FROM AUTHOR]

Biocathode microbial electrolysis cells (MECs) with electrotrophs on the cathodes are proved to be attractive for Cd(II) removal with simultaneous hydrogen production. However, the underlying roles of current and electron transfer inhibitor of 2,4-dinitrophenol (2,4-DNP) in the distribution of dissolved Cd(II) ions in the electrotrophs are largely unknown. Based on four indigenous electrotrophs ( Ochrobactrum sp X1, Pseudomonas sp X3, Pseudomonas delhiensis X5 and Ochrobactrum anthropi X7) isolated from well developed Cd(II)-removal biocathodes of MECs, a quinoline-based Cd(II) fluorescent probe was used to imaginably and quantitatively map Cd(II) ions in electrotrophs, and its response to current and 2,4-DNP in MECs. Current directed the distribution of Cd(II) ions in the electrotrophs with the occurrence of an initial quicker import and the subsequent quicker export, both of which were somewhat inhibited by 2,4-DNP. In terms of total cadmium, current always directed less cadmium in catholyte and electrotrophs with independence of the presence of 2,4-DNP. This study gives an alternative approach for developing imaging and mapping Cd(II) ions in the electrotrophs, and thus benefits for clarifying the roles of current and 2,4-DNP in electrotrophic removal of Cd(II) ions from catholyte in MECs. [ABSTRACT FROM AUTHOR]

The low cost and high performance via a simple way of fabrication are considerable challenges for Si-based anode in the application of lithium-ion batteries. In this study, we synthesize a novel free-standing Si/C anode, consisting of yolk (Si)-shell (amorphous carbon) nanoparticles and carbon nanofibers (denoted as Si@void@C/CNFs), via a facile route of template removal and electrospun. The designed yolk-shell structure help buffer the volume expansion of silicon during the discharge/charge cycles, and the intertwined CNFs are conducive to electron fast transmission and guarantee structural integrity. As expected, with a low Si content (∼23 wt%), the self-supporting electrode of Si@void@C/CNFs exhibits a high specific capacity of ∼627.5 mAh g−1 as well as 69.3% capacity retention at 0.1 A g−1 after 100 cycles, better than Si@C/CNFs (20%) and Si/CNFs (9.5%) electrodes. The superior performance of Si@void@C/CNFs indicates that it is an attractive anode material for the practical application of Lithium-ion batteries. [Display omitted] • A facile strategy is designed to prepare free-standing Si@void@C/CNFs composite. • This structure consists of the yolk-shell structure and a 3D conducting network. • The structure can buffer the volume expansion of Si and accelerate electron transfer. • The composite demonstrates ideal cycle stability as lithium-ion batteries anode. [ABSTRACT FROM AUTHOR]

Herein, an electrochemical (EC) system was applied as "co-catalyst" to enhance the activation of peroxymonosulfate (EC/Fe(III)/PMS) for efficient Sulfamethoxazole (SMX) degradation. The cathodic reduction reaction can facilitate electron transfer to Fe(III) and trigger the sustainable Fe(III)/Fe(II) redox cycle. Unexpectedly, in addition to hydroxyl radical (•OH) and sulfate radical (SO 4 •−), non-radicals mechanism including singlet oxygen (1O 2) and Fe(IV) were also found involved in EC/Fe(III)/PMS system. The degradation of SMX in EC/Fe(III)/PMS system was accomplished by the collaboration of radicals and non-radicals oxidation. The generation routes and mechanisms of involved reactive oxygen species (ROS) were explored. The relative contributions of •OH, SO 4 •−, and nonradical species for the degradation of SMX were calculated to 4.75 %, 25.31 %, and 69.94 %, respectively. Besides, multiple degradation pathways of SMX were proposed by identifying the formed byproducts. The EC/Fe(III)/PMS process could efficiently degrade SMX under the influence of co-existing ions and inactivate pathogens in the wastewater. [Display omitted] • Electrochemical system was used as a "co-catalyst" to promote the Fe(III)/Fe(II) redox cycle. • SMX is effectively degraded with a weak electrical current consumption in EC/Fe(III)/PMS system. • EC/Fe(III)/PMS system is mainly a non-radical pathway dominated by 1O 2 and Fe(IV). • EC/Fe(III)/PMS system demonstrated the ability to simultaneously eliminate contaminants and pathogens. [ABSTRACT FROM AUTHOR]

In this study, N and O co-doping carbon materials with porous structure (NOPC-x) were applied to activate peroxymonosulfate (PMS) for bisphenol (BPA) degradation and the underlying effects in affecting NOPC-x activity were revealed. Electrochemical characterization, electron paramagnetic resonance (EPR) tests, quenching and PMS adsorption experiments were applied to clarify the mechanism of BPA degradation. It's found that BPA can be completely removed within 20 min (k obs = 0.30 min−1) in the NOPC/PMS system depending on the electron transfer path with the necessity of moderate surfaced unpaired electrons for electrons delivery, which could be regulated by the modifier dosage. However, excessive surfaced unpaired electrons were unfavorable to PMS adsorption, resulting in deterioration of BPA degradation. This study indicates that controlling the amount of surfaced unpaired electrons in an appropriate range is essential to ensure the carbonaceous materials activity in PMS activation to obtain a satisfactory BPA degradation. [Display omitted] ● NOPC exhibited superior activity for BPA degradation by PMS activation. ● Increasing heteroatomic doping enhanced the amount of surfaced unpaired electrons. ● Degradation of BPA was proposed to follow a nonradical electron transfer pathway. ● The role of surfaced unpaired electrons of NOPC in PMS activation was clarified. [ABSTRACT FROM AUTHOR]

• Satisfactory degradation efficiency of pollutants was achieved by FeS/PAA system. • S(-II) and H 2 S (aq) played a significant role in Fe(II) regeneration. • •OH played a dominant role in pharmaceuticals degradation. • The R-O• generated was supposed to be quickly consumed by sulfur specie. • Degradation products of three pharmaceuticals were successfully detoxified. As peracetic acid (PAA) is being increasingly used as an alternative disinfectant, efficient activation of PAA by low-cost and environmentally friendly catalysts over a wide pH range is potentially useful for simultaneous sterilization and pharmaceutical degradation in wastewater, such as hospital wastewater. In this study, peracetic acid (PAA) was successfully activated by low-cost and environmental-friendly FeS (25 mg/L) for efficient oxidative removal of three pharmaceuticals over a wide pH range (3.0∼9.0) as indicated by 80∼100% removal rate within 5 min. As expected, Fe(II) rather than sulfur species was the primary reactive site for PAA activation, while unlike the homogeneous Fe2+/PAA system with organic radicals (R-O·) and ·OH as the dominant reactive oxidized species (ROS), ·OH is the key reactive species in the FeS/PAA system. Interestingly and surprisingly, in-depth investigation revealed the dual role of sulfur species in regulating the reactive oxidized species: (1) S(-II) and its conversion product H 2 S (aq) played a significant role in Fe(II) regeneration with a result of accelerated PAA activation; (2) however, the R-O· generated in the initial seconds of the FeS/PAA process was supposed to be quickly consumed by sulfur species, resulting in ·OH as the dominant ROS over the whole process. The selective reaction of sulfur species with R-O· instead of ·OH was supported by the obviously lower Gibbs free energy of CH 3 COO· and sulfur species than ·OH, suggesting the preference of CH 3 COO· to react with sulfur species with electron transfer. After treatment with the FeS/PAA system, the products obtained from the three pharmaceuticals were detoxified and even facilitated the growth of E. coli probably due to the supply of numerous carbon sources by activated PAA. This study significantly advances the understanding of the reaction between PAA and sulfur-containing catalysts and suggests the practical application potential of the FeS/PAA process combined with biotreatment processes. [Display omitted] [ABSTRACT FROM AUTHOR]

Photoreforming of plastic waste is a novel approach, which can not only degrade plastic waste into valuable chemicals, but also produce high-energy-density hydrogen fuels. Here, we developed an in-situ derived carbon nitride-carbon nanotubes-NiMo hybrids via NiMo-assisted catalysis route, which works as an efficient and stable photocatalyst for plastics photoreforming. The strong π-π interaction between in-situ derived CNTs and CN promotes electron transfer, increases carrier lifetime and improves photocatalytic activity. The DFT calculations and single-particle PL quenching phenomenon confirmed the strong interface effect and charge transport for CN-CNTs-NM. In addition, the strong interaction between photocatalyst and ethylene glycol in plastics was observed in situ by single-particle PL. This work provides a smart strategy of utilizing in-situ derived π-π interaction as well as direct evidence of the charge transfer from the photocatalysts to ethylene glycol, which provides guidance for the rational design of highly efficient photocatalysts for plastics photoreforming. Photoreforming of plastics is a novel approach, which can not only degrade plastic waste into valuable chemicals, but also produce high-energy-density hydrogen fuels. Here, we developed an in-situ derived carbon nitride-carbon nanotubes-NiMo hybrids (CN-CNTs-NiMo) via NiMo self-catalytic route, which works as an efficient and stable photocatalyst for photoreforming of plastics under alkaline conditions. [Display omitted] • PET photoreforming can convert plastics into value-added chemicals and hydrogen using sunlight. • In situ-derived CN-CNTs-NM hybrids were synthesized NiMo-assisted catalysis route for photoreforming of PET. • Single-particle PL and DFT calculations confirm the existence of π-π interactions between CN and CNTs. • The real-world applicability of plastics photoreforming was confirmed by photoreforming of PET bottle. • The mechanism of plastics photoreforming was investigated in situ using single-particle PL. [ABSTRACT FROM AUTHOR]

[Display omitted] • A heterogeneous catalytic system of NaBiO 3 for PMS without light irradiation was investigated. • Both radical (SO 4 −• and •OH) and non-radical (1O 2) were contributed to BPAF degradation. • The contribution rate of 1O 2 , · SO- 4, and · OH was calculated as 80.4%, 8.7%, and 9.9%, respectively. It has been shown previously that the NaBiO 3 (NBO) could efficiently photocatalytically degrade organic contaminants because of its excellent photocatalytic property. In this study, we proposed a heterogeneous catalytic system of NBO for peroxymonosulfate (PMS) without light irradiation. The results showed that NBO/PMS exhibited excellent performance toward bisphenol AF (BPAF) degradation and mineralization. The effectiveness of the NBO/PMS system was also investigated in different multicomponent systems. The effects of initial pH, NBO dosages, and PMS concentration for BPAF degradation were also investigated. Radical quenching experiments combined with electron spin resonance analysis indicated that singlet oxygen (1O 2) was the main reactive oxygen species, and · SO 4 - and · OH– radicals participated in the process. X-ray photoelectron spectroscopy revealed the main catalytic mechanism: lattice oxygen (O vac) was extruded during the transformation of Bi(V) to Bi(III) to form and activate oxygen (O*), and the generated O* between the [BiO 6 ] regular octahedral layers reacted with PMS on the NBO surface to form 1O 2. Based on the results of the Bi element, it is suggested that the activation process proceeded through electron transfer from NBO to PMS. The stability of NBO and applicability of the NBO/PMS system in a natural water environment were explored. This work provides a novel approach to PMS activation and the potential use of NBO for the decontamination of organic pollutants. [ABSTRACT FROM AUTHOR]

A stressful heavy metal circumstance disfavors production of acetate from bicarbonate reduction in the biocathode of microbial electrosynthesis system (MES) with simultaneous function of heavy metal removal/recovery. It is of great interest to explore effective approaches to moderate the heavy metal stress with achievement of simultaneous enhanced acetate production and heavy metal removal in MES. Herein, a magnetic field strength of 100 mT was successfully employed to moderate Cr(VI) stress, achieving simultaneous production of acetate at a rate of 1.48 ± 0.01 mg/L/h and Cr(VI) removal at a rate of 1.67–2.42 mg/L/h in the Serratia marcescens Q1 catalyzed cathode of MES under periodical addition of bicarbonate and Cr(VI), 1.35-fold (acetate production) and 1.34–1.46 times (Cr(VI) removal) of those in the controls in the absence of magnetic field. This simultaneous efficient acetate production and Cr(VI) removal was regulated by the magnetic field and the stressful Cr(VI), which induced the S. marcescens to physiologically release additive amounts of extracellular polymeric substances with a compositional diversity and containing the electrochemically active c -type cytochromes to facilitate extracellular electron transfer. This study confirmed the importance of magnetic field in developing the S. marcescens catalytic activity for moderating Cr(VI) stress, and thus provided a feasible approach for simultaneous efficient acetate production and Cr(VI) removal/recovery in MES, from waters contaminated with Cr(VI). Image 1 • An external magnetic field moderated the stress of Cr(VI) to Serratia marcescens. • Simultaneous enhanced acetate production and Cr(VI) removal was observed. • External magnetic field and stressful Cr(VI) induced S. marcescens to release EPS. • The EPS contained c -type cytochromes to facilitate extracellular electron transfer. [ABSTRACT FROM AUTHOR]

In this study, the catalytic ability and mechanisms involved in activating peroxymonosulfate (PMS) with Mn 3 O 4 and the degradation pathways of bisphenol-AF (BPAF) removal was investigated. SO 4 −• and · OH which were explored by and scavenging tests were the major reactive radicals in the Mn 3 O 4 /PMS system. A simple simulation algorithm was also used to calculate the relative concentrations of SO 4 −• ([SO 4 −•]) and · OH ([ · OH]) which were 8.39 × 10 −15 M and 6.96 × 10 −13 M, respectively. The mechanism for the electron transfer between the Mn (II) and Mn (III) species was discussed. Three degradation pathways of BPAF were determined by the GC/MS and LC/MS technology, including chemical mechanism of oxidation, hydroxylation, electron transfer, polymerization, and ring-cleavage. In addition, the results suggested that the Mn 3 O 4 /PMS system had an efficient total organic carbon (TOC) removal rate and excellent environmental adaptability, the removal rate of TOC being as high as 73.2% in the control condition. Furthermore, the reuse experiments and the comparison on the structural and componential changes of Mn 3 O 4 powder before and after reaction demonstrated that the Mn 3 O 4 catalyst possessed excellent stability and reusability. Finally, a maximum BPAF degradation of approximately 90.0% was achieved on the optimal conditions for 500 mg/L Mn 3 O 4 dosage, 4 mM PMS concentration, 7.0 ± 0.2 initial pH, and 5 mg/L BPAF concentration respectively. And the effect of the coexisting anions and natural environmental water quality were also considered. This study demonstrated the Mn 3 O 4 /PMS system can be considered as a green approach for the removal of environmental reluctant pollutants. Image 1 • A systematic study of using Mn 3 O 4 to activate PMS for BPAF removal was investigated. • The excellent mineralization of the system was confirmed. • The high stability and reusability of the Mn 3 O 4 were distinguished. • Both •OH and SO4−• were responsible for BPAF degradation. • Three degradation pathways of BPAF were proposed. [ABSTRACT FROM AUTHOR]