Wastewater treatment plants simultaneously emit greenhouse gases and rely on external carbon sources, presenting both a challenge and an opportunity for carbon circularity. We develop a comprehensive life-cycle assessment of 32 Waste-to-Chemical pathways that integrate thermochemical and electrochemical conversions in sequential or parallel architectures to convert CH4 and CO2 into reusable carbon sources for in-plant utilization. Sequential thermochemical-electrochemical coupling consistently delivers the strongest climate benefit, with formate identified as the optimal product, reducing emissions up to ~35% reduction relative to direct-emission baselines. We further validate this pathway experimentally using commercially available Pd/Al2O3 catalysts for CH4 thermochemical oxidation and Bi2O3 catalysts for CO2 electroreduction in a porous solid electrolyte reactor. Residual heat generated during CH4 oxidation enhances downstream CO2 electroreduction, enabling 97.2 ± 1.2% Faradaic efficiency toward separation-free formate at 150 mA cm−2 and 45 °C. These results validate that commercially relevant catalysts and thermally coupled operation can deliver experimentally validated performance aligned with system-level projections. This framework establishes a scalable strategy for embedding carbon circularity into wastewater infrastructure and transforming wastewater treatment plants into distributed platforms for low-carbon chemical production.

The abuse of antibiotics leads to widespread antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in water systems, threatening public health. Existing disinfection technologies have limitations including the generation of toxic disinfection byproducts (DBPs) and inefficiency in eliminating intracellular ARGs. Herein, we provide an effective and toxic-DBP-free disinfection approach to remove ARB/ARGs by reactive species generated via activation of sodium percarbonate (SPC) inside and outside cells with naturally abundant sunlight. Combining in situ characterization and theoretical calculation, we reveal that CO3•–, •OH, and O2•– are generated both intra- and extracellularly. SPC passively diffusing into cells complexes with intracellular substances (e.g., heme, Fe–S cluster protein, and cytochrome c) to produce various reactive species in situ under sunlight irradiation, leading to the locally increased oxidation levels within cells. These reactive species synergistically contribute to the collapse of the antioxidant system, resulting in effective ARB inactivation and ARGs degradation. Owing to its limited reactivity toward background substances in water and effective intracellular oxidation mechanisms, the SPC/sunlight system demonstrates efficient ARB disinfection capabilities without any toxic DBPs generation in real water. This study presents a green, cost-effective, and toxic-DBP-free alternative for efficient ARB/ARGs removal with deep insights into intracellular oxidation mechanisms.

Hydrogen peroxide (H2O2) photosynthesis from H2O and O2 using covalent organic frameworks (COFs) is a sustainable approach, yet its efficiency is restricted by a sluggish water oxidation reaction (WOR) due to insufficient water adsorption and charge separation. Herein, we propose a facile and universal polar center spatial-manipulation strategy to enable efficient H2O2 photosynthesis by COFs via converting high-polarity C═N linkages into 4-carboxyl-quinolyl linkages with weakened-polarity quinoline backbones and ultra-polar carboxyl side chains (forming COF-TBC). This polar-center side-shifting strategy concurrently enhances water adsorption (via the polar carboxyl side chain) and water activation (enabled by efficient exciton formation and separation along the low-polarity quinoline backbone) by COF-TBC, lowering the energy barrier of the rate-determining WOR and achieving outstanding and stable H2O2 photosynthesis from O2 and H2O without sacrificial agents (5624 µmol g−1 h−1, accumulating to 41 mM, solar-to-chemical efficiency of 0.72%). The polar-center side-shifting strategy can be extended to modify other COFs for enhancing H2O2 photosynthesis, indicating its universality. COF-TBC maintains high H2O2 yield in complex real-water matrices and can be integrated into membrane-based and continuous-flow reactors for successive H2O2 generation under natural sunlight. COF-TBC also exhibits efficient photocatalytic performance toward organic contaminant degradation and microorganism inactivation, highlighting its broad potential for water purification.

Freeze–thaw (FT) cycle, a ubiquitous and important physical process in natural environments, may influence the horizontal gene transfer (HGT) process of antibiotic-resistant genes (ARGs), yet its impact and underlying mechanisms remain unclear. This study investigated the impact and mechanisms of FT cycles on ARG conjugative transfer among intra- and interspecies under different solution ionic strength conditions. The results showed that despite ionic strengths and species pairs, different FT treatment cycles induced diverse influences on ARG conjugation frequency with inhibition effect of 1 FT cycle (decreased by 3.5–76-fold) and facilitation effect of 2 and 3 FT cycles (promoted by 2–27-fold). The reduced conjugation frequency after 1 FT treatment cycle is mainly attributed to energy deficiency caused by the starvation process during FT treatment. The enhanced cell–cell adhesion induced by the increased hydrophobicity and secretion of bacterial extracellular polymeric substances (EPS) facilitated the formation of conjugative pilus, primarily promoting the ARG conjugative transfer process after 2 and 3 FT treatment cycles. The results of our study clearly show that FT cycles (intensified by the ongoing climate change) exhibit profound influence on the dissemination of ARGs, which helps understand and predict ARG risks in different natural environments.

Insufficient oxygen mass transfer and inadequate charge separation are two critical factors restricting the photocatalytic efficiency of covalent organic frameworks (COFs) for water purification. Here, we develop a facile strategy to simultaneously boost oxygen mass transfer and charge separation in COFs through constructing efficient oxygen capture tentacles via replacing conventional pyridine groups with nicotinic-acid/methyl-nicotinate groups, which have tunable oxygen affinity. Molecular dynamics simulations and in situ characterizations reveal that compared to pyridine groups in COF-EP1 and nicotinic-acid groups in COF-EP2, respectively serving as weak and medium oxygen capture tentacles, methyl-nicotinate groups in COF-EP3 can serve as strong oxygen capture tentacles due to their superb oxygen affinity, which can enhance oxygen interaction energies and thus promote oxygen mass transfer. Owing to the optimal charge polarization, methyl-nicotinate groups in COF-EP3 also strengthen internal electric fields to facilitate charge separation. COF-EP3 thus achieves exceptional photocatalytic degradation performance towards sulfadiazine (99.5% removal in 25 min, k = 0.21 min−1), which is 16.2 and 2.8 times higher than that of COF-EP1 (k = 0.013 min−1) and COF-EP2 (k = 0.076 min−1), respectively. Besides, COF-EP3 exhibits high sulfadiazine degradation performance in complicated water matrices, continuous-flow system, and scaled-up reactor, demonstrating its practical application potential.

The effects and mechanisms of carbon (C)- and nitrogen (N)-deficient nutrient conditions (prevalent in natural environment) on bacterial mobile performance in porous media are unclear. This study systematically investigated the transport/retention performance of Gram-negative Escherichia coli and Gram-positive Bacillus subtilis experiencing different nutrient conditions (i.e. nutrient-sufficient, C-deficient, or N-deficient conditions) in column, parallel plate flow chamber (PPFC) and microfluidic chamber systems. We found that compared to those in nutrient-sufficient condition, bacteria (regardless of their type) exposure to C-deficient nutrient condition exhibited 7–14% reduced mobility in porous media, whereas those experienced N-deficient condition had 7–20% enhanced transport in both simulated electrolyte solutions and real groundwater samples. The underlying mechanisms driving to different mobile performance of bacteria exposure to different nutrient conditions were correlated with the composition of proteins (one major component of extracellular polymeric substances (EPS)). Compared to nutrient-sufficient condition, C-deficient condition increased EPS hydrophobicity via enhancing hydrophobic amino acids contents and altering secondary structure within proteins thus decreased bacterial transport, while N-deficient condition decreased EPS hydrophobicity through decreasing the abundance of hydrophobic amino acids within proteins and increased cell mobility. The results showed that via changing cell surface hydrophobicity, exposure bacteria to different nutrient conditions could induce different mobile performance of bacteria.

Antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) pose global threats to human health and ecological safety. Activation of percarbonate (PC) by eco-friendly bismuth oxyiodide (BiOI) is a promising ARB/ARGs removal technique, yet its efficiency is hindered by the insufficient exposure of reactive Bi sites. Herein, we provide a facile protocol to fabricate BiOI with remarkable PC activation efficiency (BOI-C) for the ultrafast ARB/ARGs removal via modulating reactive Bi sites through introducing optimal Bi3-oxygen vacancy (OV) sites on the unsaturated facets. We show that BOI-C with optimal amount of Bi3-OV site can efficiently activate 50 µM PC to rapidly disinfect 7-log ARB to the limit of detection within only 4 min. Moreover, this reaction system can effectively degrade the released ARG and suppress the horizontal gene transfer process, greatly decreasing the risks of ARG dissemination. Negligible toxic halogen-containing disinfection byproducts is generated during the disinfection process, indicating the outstanding ecological safety of BOI-C/PC system. The reaction system can also effectively disinfect ARB under complex water chemistries including a broad pH range (3–9), high ionic strengths (up to 150 mM), copresence of natural organic matter (up to 10 mg L−1), and diverse actual water samples including tap water, lake water, groundwater and aquaculture tailwater. Furthermore, it can also be assembled into a filtration system for successive ARB disinfection, demonstrating the feasibility for practical application. The catalytic system also exhibits excellent ARB disinfection performance across various bacterial strains and effective degradation performance towards different types of emerging organic pollutants, suggesting its universal decontamination capability. Combining in-situ characterizations and theoretical calculations, we reveal that Bi3-OV sites on the unsaturated facets of BOI-C facilitate the p-p interaction with peroxy O atoms of PC molecules and trigger the electron transfer as well as the subsequent cleavage of peroxy bonds, generating abundant CO3•− for the ultrafast ARB disinfection. The results of this study show that BOI-C/PC system can be employed to effectively remove antibiotic resistance in real water.

Current antibiotic-resistant bacteria (ARB) disinfection techniques commonly rely on large dosages of oxidants, resulting in the presence of considerable amounts of residuals and toxic disinfection byproducts (DBPs) in water. Herein, we propose a highly effective ARB disinfection approach via activating an ultralow concentration (10 μM) of chlorite (ClO2–) by naturally abundant sunlight to generate various reactive species (i.e., HO•, Cl•, ClO•, and ClO2) with negligible generation of halogenated DBPs. Combining in situ characterization with theoretical calculations, we reveal that, in addition to the photolysis of ClO2– in the bulk solution, ClO2– ions electrostatically adsorbed on the positive local sites of lipids can boost light absorption and facilitate the in situ generation of reactive species upon sunlight irradiation, enabling more efficient attacks toward cell membranes and the intracellular antioxidant enzyme system. The intracellular antibiotic resistance genes (ARGs) are then released and further degraded, inhibiting horizontal ARG transfer. This approach can also achieve excellent ARB disinfection performance in real water matrices (e.g., lake and river water) in 1 L tanks and 500 mL plastic bottles with natural sunlight irradiation. Overall, this work presents an efficient, safe, and sustainable method to inactivate ARB with deep insights into disinfection mechanisms at the subcellular level.

Insufficient charge separation and sluggish two-electron water-oxidation reaction are two critical factors restricting the photosynthesis performance of metal-free covalent organic frameworks (COFs) for hydrogen peroxide (H2O2) generation from naturally abundant water and air. Herein, we develop a facile strategy to simultaneously boost the charge-separation efficiency and water-oxidation capability through constructing short and rapid charge-transfer tunnels within highly charge-confined COFs via replacing the phenyl with pyrimidine. Compared with a single charge-transfer tunnel within a lowly charge-confined COF-5-(4-aminophenyl)pyrimidin-2-amine (APM) with pyrimidine, dual charge-transfer tunnels are constructed within a highly charge-confined COF-5,5′-bipyrimidine-2,2′-diamine (BPM) with bipyrimidine due to the ground-state charge transfer between para-carbon and meta-nitrogen, which significantly accelerates the intermolecular charge-transfer process and prevents charge recombination. This strategy also decreases the energy barrier of rate-determining water oxidation in H2O2 photosynthesis and thus promotes the effective generation of the key *OH intermediates, facilitating the generation of H2O2 at a production rate of 5521 μmol g−1 h−1 from water, oxygen and light without sacrificial reagents or additional energy consumption by COF-BPM. Furthermore, COF-BPM can also efficiently produce H2O2 under broad pH conditions, in widely available real water, on a floatable foam sheet, in a continuous-flow reactor and in a scaled-up reactor by using natural solar light for water decontamination.

The initial adhesion of microbes onto plastics is crucial for the subsequent formation of the plastisphere, which might be affected by signal molecules commonly present in bacteria-related environments that regulate cell-to-cell communication. Herein, the initial retention performance of E. coli onto six types of plastics, both without and with N-acyl-homoserine lactones (AHLs, a common signal molecule) at concentrations ranging from 10 ng/L to 100 μg/L in suspension, was determined to reveal the influence of signal molecules on the formation of the plastisphere. We found that AHLs coexisting in suspensions significantly enhanced bacterial adhesion performance onto plastics, regardless of plastic types and AHL types, with a more pronounced enhancement observed at higher AHL concentrations. This enhanced bacterial adhesion induced by AHLs also held true in solutions containing humic acid, in river water, and in sewage. AHLs stimulated the synthesis of EPS, enhanced EPS hydrophobicity by altering the protein/polysaccharide ratio and its secondary structures, and upregulated pathways related to flagellar assembly, quorum sensing, protein production, and biofilm formation, thereby enhancing bacterial adhesion capability onto plastics. Moreover, AHLs adsorbed onto plastic surfaces could induce chemoattraction effects, further promoting bacterial adhesion performance. Obviously, through various mechanisms, the signal molecules greatly influence the initial adhesion of bacteria onto plastics in aquatic systems.

Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in aquatic environments pose threats to ecosystem safety and human health, which could not be efficiently removed by conventional disinfection techniques. Herein, layered FeOCl with coordinatively unsaturated Fe sites were fabricated and used to activate Fe(VI) for the efficient ARB/ARG removal in the present study. We found that highly reactive Fe(IV)/Fe(V) intermediates were generated in the FeOCl/Fe(VI) system, rapidly disinfecting 1 × 107 CFU mL–1 ARB to below the limit of detection within only 6 min. Via the combination of in situ characterization and theoretical calculations, we revealed that Fe(VI) was preferentially adsorbed onto Fe sites on the (010) plane of FeOCl and subsequently activated to produce reactive Fe(IV)/Fe(V) through direct electron transfer. Meanwhile, O2•– generated from O2 activation on the FeOCl surface enhanced Fe(VI) conversion to Fe(IV)/Fe(V). During the disinfection process, intracellular/extracellular ARGs and DNA bases were simultaneously degraded, inhibiting the potential horizontal gene transfer process. The FeOCl/Fe(VI) system could effectively disinfect ARB under complex water matrices and in real water samples including tap water, lake water, and groundwater. When integrated into a continuous-flow reactor, the FeOCl/Fe(VI) system with excellent stability successively disinfected ARB. Overall, the FeOCl/Fe(VI) system showed great promise for eliminating ARB/ARGs from water.

Injection of bacteria with petroleum degrading capability into contaminated sites is one of the most cost-effective and environmental friendly strategies for the successful remediation of petroleum-contaminated groundwater. The successful in-situ bioremediation of petroleum contamination in subsurface is greatly impacted by the mobile/retention performance of petroleum-degrading bacteria in porous media, which yet is not well understood. The present study systematically investigated the mobile performance of petroleum-degrading strains in porous media with petroleum contamination under environmentally relevant solution and flow conditions. We found that although the mobile performance of petroleum-degrading bacteria was similar to petroleum non-degrading bacteria in uncontaminated porous media, bacteria containing different petroleum degrading function yet exhibited opposite transport behaviors in petroleum contaminated porous media. Enhanced mobility in porous media with petroleum contamination was achieved for petroleum non-degrading bacteria, while reduced mobility was obtained for petroleum-degrading bacteria. Combining the batch adsorption experiments, capillary chemotaxis assays, in-situ microfluidic chamber experiments together with theoretical calculation, we found that the opposite mobile performance observed for bacteria containing different petroleum degrading functions could be mainly attributed to their different chemotactic responses towards petroleum with negative and positive chemotaxis response respectively for non- and petroleum-degrading bacteria. Clearly, pollutant-degrading bacteria exhibited different mobile performance from non-degrading bacteria in contaminated porous media. The previous findings achieved from the model bacteria without pollutant-degrading capability could not be simply used to predict the mobile performance of pollutant-degrading bacteria. To ensure the successful implementation of in-situ bioremediation, the mobility of pollutant-degrading bacteria in contaminated porous media should be fully understood.

Sunlight-driven photosynthesis by covalent organic frameworks (COFs) from water and air without using sacrificial reagents is a promising H2O2 fabrication approach, but is still restricted by the insufficient charge separation and sluggish 2e- water oxidation process. Herein, we provide a facile strategy to simultaneously improve charge separation and water oxidation in COFs via confining the charge transfer pathways from two diversion ones to a confluence one through regulating the site of nitrogen in bipyridine. Combining in-situ characterization with computational calculations, we reveal that compared to COF-BD1 containing two diversion charge transfer pathways, the charge transfer pathway in COF-BD2 is confined to a confluence one due to the electron-deficiency effect of nitrogen, which greatly accelerates the intermolecular and out-of-plane charge transfer. Via effectively reducing the energy barrier of rate-determining water oxidation reaction, the subsequent water oxidation process to produce key *OH intermediate in COF-BD2 is also greatly facilitated, boosting the yield of H2O2 (5211 μmol g-1 h-1) from water, oxygen, and light without sacrificial agents or additional energy consumption. We further demonstrate that H2O2 can be efficiently produced by COF-BD2 in broad pH range, in real water, and in enlarged reactor with using natural sunlight for water decontamination.

The proliferation and spread of antibiotic-resistant bacteria (ARB) significantly threaten human health and ecosystem. Periodate (PI) based advanced oxidation process has potentials for water purification but limited by complex activators or activation process. Herein, we demonstrated that H2O2 could be used to activate PI, achieving efficient ARB disinfection performance. Particularly, we found that the PI/H2O2 system (0.1 mM for both oxidants) could inactivate ARB (Escherichia coli) within 35 min. The intracellular defense system attacked by HO· radicals generated in the disinfection system, resulting in the inactivation of ARB. Antibiotic resistance genes (ARGs) released with the lysis of cell membrane could be further degraded by HO· radicals. Moreover, we found that the PI/H2O2 system was effective to inactivate ARB in a broad range of ionic strengths, with coexisting common ions and humic acid, as well as in four typical actual water bodies. The PI/H2O2 system could also efficiently disinfect other types of bacteria and degrade typical organic contaminants. In addition, under sunlight irradiation, the ARB inactivation performance of the PI/H2O2 system could be greatly improved. This study provided a practical and efficient way for decontaminating ARB/ARGs-polluted water.

Antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) pose a significant threat to both ecosystems and human health. Owing to the excellent catalytic activity, eco-safety, and convenience for defect engineering, BiOBr with oxygen vacancies (OVs) of different density thus were fabricated and employed to activate H2O2 for ARB disinfection/ARGs degradation in present study. We found that BiOBr with OVs of appropriate density induced via ethanol reduction (BOB-E) could effectively activate H2O2, achieving excellent ARB disinfection and ARGs degradation efficiency. Moreover, this disinfection system exhibited remarkable tolerance to complex water environments and actual water conditions. In-situ characterization and theoretical calculations revealed that OVs in BOB-E could effectively capture and activate aqueous H2O2 into HO· and O2·−. The generated reactive oxygen species combined with electron transfer could damage the cell membrane system and degrade genetic materials of ARB, leading to effective disinfection. The impressive reusability, high performance achieved in two immobilized reaction systems (packed column and baffled ditch reactor), excellent degradation of emerging organic pollutants supported the feasibility of BOB-E/H2O2 system towards practical water decontamination. Overall, this study not only provides insights into fabrication of bismuth-based catalysts for efficient ARB disinfection/ARGs degradation via OVs regulation, but also paves the way for their practical applications.

The successful implementation of in-situ bioremediation of nonaqueous-phase liquid (NAPL) contamination in soil-groundwater systems is greatly influenced by the migration performance of NAPL-degrading bacteria. However, the impact and mechanisms of NAPL on the migration/retention of pollutant-degrading bacteria remain unclear. This study investigated the migration/retention performance of A. lwoffii U1091, a strain capable of degrading diesel while producing surfactants, in porous media without and with the presence of mono- and multicomponent NAPL (n-dodecane and diesel) under environmentally relevant conditions. The results showed that under all examined conditions (5 and 50 mM NaCl solution at flow rates of 4 and 8 m/d), the presence of n-dodecane/diesel in porous media could reduce the migration and enhance retention of A. lwoffii in quartz sand columns. Moreover, comparing with mutlicomponent NAPLs of n-dodecane, the monocomponent NAPLs (diesel) exhibited a greater reduction effect on the retention of A. lwoffii in porous media. Through systemically investigating the potential mechanisms via tracer experiment, visible chamber experiment, and theoretical calculation, we found that the reduction in porosity, repulsive forces and movement speeds, the presence of stagnant flow zones in porous media, particularly the biosurfactants generated by A. lwoffii contributed to the enhanced retention of bacteria in NAPL-contaminated porous media. Moreover, owing to presence of the greater amount of hydrophilic components in diesel than in n-dodecane, the available binding sites for the adsorption of bacteria were lower in diesel, resulting in the slightly decreased retention of A. lwoffii in porous media containing diesel than n-dodecane. This study demonstrated that comparing with porous media without NAPL contamination, the retention of strain capable of degrading NAPL in porous media with NAPL contamination was enhanced, beneficial for the subsequent biodegradation of NAPL.

Owing to their capability to produce reactive oxygen species (ROS) under solar irradiation, covalent organic frameworks (COFs) with pre-designable structure and unique architectures show great potentials for water purification. However, the sluggish charge separation, inefficient oxygen activation and poor structure stability in COFs restrict their practical applications to decontaminate water. Herein, via a facile one-pot synthetic strategy, we show the direct conversion of reversible imine linkage into rigid thiazole linkage can adjust the $π$-conjugation and local charge polarization of skeleton to boost the exciton dissociation on COFs. The rigid linkage can also improve the robustness of skeleton and the stability of COFs during the consecutive utilization process. More importantly, the thiazole linkage in COFs with optimal C 2p states (COF-S) effectively increases the activities of neighboring benzene unit to directly modulate the O2-adsorption energy barrier and improve the ROS production efficiency, resulting in the excellent photocatalytic degradation efficiency of seven toxic emerging contaminants (e.g. degrading \textasciitilde99% of 5þinspace}mgþinspace}L−1 paracetamol in only 7þinspace}min) and effective bacterial/algal inactivation performance. Besides, COF-S can be immobilized in continuous-flow reactor and in enlarged reactor to efficiently eliminate pollutants under natural sunlight irradiation, demonstrating the feasibility for practical application.

The influence and mechanisms of starvation on the bacterial mobile performance in porous media with different nutrition conditions are not well understood. The present study systematically investigated the impacts of starvation on the mobility and attachment of both Gram-negative and Gram-positive strains in porous media without and with nutrients on surfaces in both simulated and real water samples. We found that regardless of strain types and water chemistries, starvation would greatly inhibit bacterial attachment onto bare porous media without nutrients yet could significantly enhance cell attachment onto porous media with nutrients on their surfaces. The mechanisms driving the opposite transport behaviors induced by starvation in porous media without and with nutrients were totally different. We found that the starvation process decreased cell motility and increased repulsive force between bacteria and porous media via decreasing cell sizes and zeta potentials, reducing EPS secretion and cell hydrophobicity, thus increasing transport/inhibiting attachment of bacteria in porous media without nutrients on sand surfaces. In contrast, through strengthening the positive chemotactic response of bacteria to nutrients, the starvation process greatly enhanced bacterial attachment onto porous media with nutrients on sand surfaces. Clearly, via modification of the nutrient conditions in porous media, the mobility/attachment performance of bacteria could be regulated.

Harmful algal blooms pose tremendous threats to ecological safety and human health. In this study, simulated solar light (SSL) irradiation was used to activate periodate (PI) for the inactivation of Microcystis aeruginosa and degradation of microcystin-LR (MC-LR). We found that PI-SSL system could effectively inactivate 5 × 106 cells·mL−1 algal cells below the limit of detection within 180 min. ·OH and iodine (IO3· and IO4·) radicals generated in PI-SSL system could rupture cell membranes, releasing intracellular substances including MC-LR into the reaction system. However, the released MC-LR could be degraded into non-toxic small molecules via hydroxylation and ring cleavage processes in PI-SSL system, reducing their environmental risks. High algae inactivation performance of PI-SSL system in solution with a wide pH range (3–9), with the coexisting anions (Cl−, NO3− and SO42−) and the copresence of natural organic matters (humic acid and fulvic acid), real water (lake water and river water), as well as in continuous-flow reactor (14 h) were also achieved. In addition, under natural sunlight irradiation, effective algae inactivation could also be achieved in an enlarged reactor (1 L). Overall, our study showed that PI-SSL system could avoid the inference by the background substances and could be employed as a feasible technique to treat algal bloom water.

Abstract The insufficient exciton (e−-h+ pair) separation/transfer and sluggish two-electron water oxidation are two main factors limiting the H2O2 photosynthetic efficiency of covalent organic frameworks (COFs) photocatalysts. Herein, we present an alternative strategy to simultaneously facilitate exciton separation/transfer and reduce the energy barrier of two-electron water oxidation in COFs via a dicyano functionalization. The in situ characterization and theoretical calculations reveal that the dicyano functionalization improves the amount of charge transfer channels between donor and acceptor units from two in COF-0CN without cyano functionalization to three in COF-1CN with mono-cyano functionalization and four in COF-2CN with dicyano functionalization, leading to the highest separation/transfer efficiency in COF-2CN. More importantly, the dicyano group activates the neighbouring C atom to produce the key *OH intermediate for effectively reducing the energy barrier of rate-determining two-electron water oxidation in H2O2 photosynthesis. The simultaneously enhanced exciton separation/transfer and two-electron water oxidation in COF-2CN result in high H2O2 yield (1601 μmol g−1 h−1) from water and oxygen without using sacrificial reagent under visible-light irradiation. COF-2CN can effectively yield H2O2 in water with wide pH range, in different real water samples, in scaled-up reactor under natural sunlight irradiation, and in continuous-flow reactor for consecutively producing H2O2 solution for water decontamination.