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[Display omitted] In the present study, an innovative carbon self-doped g-C 3 N 4 (CCN) loaded with ultra-low CeO 2 (0.067–0.74 wt%) composite photocatalyst is successfully synthesized via a facile one-pot hydrothermal and calcination method. The CeO 2 /CCN exhibits superior photocatalytic performance for tetracycline degradation (78.9% within 60 min), H 2 O 2 production (151.92 μmol L-1 within 60 min), and Cr(VI) reduction (99.5% within 40 min), which much higher than that of g-C 3 N 4 , CCN, CeO 2 , and CeO 2 /g-C 3 N 4. The enhanced photocatalytic performance is originated from the fact that the doping of C can efficaciously broaden the utilization range of solar light and improve the reduction ability of photogenerated electrons. Meanwhile, the ultra-low loading of CeO 2 can effectually promote the migration of photogenerated electrons and enhance the specific surface area. Besides, the experiments of pH effect and cycle ability indicate that CeO 2 /CCN has excellent durability and stability. Finally, the photocatalytic mechanism of CeO 2 /CCN is systematically discussed. This work proves that combining element doping and semiconductor coupling is a promising strategy to design high-efficiency g-C 3 N 4 -based photocatalysts. [ABSTRACT FROM AUTHOR]

CeO 2 nanoparticles are successfully loaded on carbonate doped Bi 2 O 2 CO 3 (CBOC) nanosheets by a facile hydrothermal and low-temperature calcination method. CeO 2 /CBOC heterojunction shows significantly enhanced photocatalytic activity, when 35 mg of CeO 2 /CBOC photocatalyst is added to tetracycline (TC) solution (20 mg/L, 100 mL), about 79.5% TC is degraded within 90 min under visible light irradiation, which is much higher than that of original CeO 2 and CBOC. According to photoelectrochemical characterization and active radical capture experiments, the Z-scheme electron transfer mechanism is the reason for the significant enhancement of photocatalytic activity. Besides, the XPS results indicate that Ce4+/Ce3+ redox pairs are formed at the contact interface between CeO 2 and CBOC, which is conducive to the transfer of photoexcited electrons and production of superoxide radicals. Additionally, the photocatalytic mechanism and possible degradation pathway of TC is proposed through free radical trapping experiments and liquid chromatography-mass (LC-MS) analysis. This study will accumulate experience for the combination of CeO 2 and bismuth-based nanomaterials, and provide a feasible way to design wide band-gap bismuth-based photocatalysts, thereby achieving efficient visible light degradation of environmental pollutants. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) have been widely used in Fenton-like water treatment, but studies on the selective induction of H 2 O 2 to produce singlet oxygen (1O 2) are rare. Herein, a carbon nitride supported high-loaded single-atom Cu-N 3 catalyst (Cu-CN, Cu load is 15.46 wt%) is prepared to activate H 2 O 2 to selectively form 1O 2. Experimental and DFT calculation results reveal that the key factor for 1O 2 production is the Cu-N 3 coordination structure. Specifically, Cu-N 3 coordination structure is conducive to decomposing H 2 O 2 into·OOH/·O 2 -. Besides, the density of Cu-N 3 sites is another key factor, high Cu-N 3 site density is conducive to the rapid conversion of·OOH/·O 2 - to 1O 2. Benefitting from the dominant role of 1O 2 , the Fenton-like degradation performance of Cu-CN/ H 2 O 2 system is not disturbed under high salinity conditions, and the performance is significantly enhanced at high pH. This work represents an important reference in understanding SACs for activated H 2 O 2 to generate 1O 2. [Display omitted] • Cu-N 3 single-atom catalyst (CuCN) can induce H 2 O 2 to selectively produce 1O 2. • The Cu-N 3 coordination structure is the key factor for 1O 2 production. • CuCN exhibits excellent Fenton-like performance under high salinity conditions. • The density of Cu-N 3 sites can modulate the Fenton-like active species. [ABSTRACT FROM AUTHOR]

[Display omitted] • FePc/g-C 3 N 4 catalysts were successfully synthesized by a facile one-pot method. • π-π interaction between FePc and g-C 3 N 4 forms a fast electron transfer channel. • g-C 3 N 4 provides photogenerated electrons to accelerate Fe (III) / Fe (II) cycles. • CNFP exhibits excellent photo-Fenton performance for OTC degradation. • CNFP exhibits a wide pH range, good anti-interference ability and stability. Antibiotic contamination has become an environmental problem that cannot be ignored, and there is an endless demand for high performance advanced oxidation technologies to efficiently remove antibiotics from wastewater. Iron (II) phthalocyanine (FePc) with monoatomic dispersed iron sites has great potential for Fenton-like catalysis, but its tendency to aggregate in aqueous environments leads to self-degradation, poor electrical conductivity, and masking of active centers, which severely limits its practice application. Herein, aiming at these disadvantages, a novel FePc/g-C 3 N 4 (CNFP)/H 2 O 2 photo-Fenton system was constructed. In CNFP, the highly dispersed FePc on g-C 3 N 4 not only avoided the self-degradation caused by high aggregation, but also provided more active centers. Additionally, the π-π interaction between FePc and g-C 3 N 4 formed a quick-speed electron transfer routeway, which enabled the fast transfer of photogenerated electrons. g-C 3 N 4 as a photocatalytic center can continuously provide photogenerated electrons for FePc to realize the rapid regeneration of Fe(II). In CNFP/H 2 O 2 photo-Fenton system, the coexistence of radicals and non-radicals (OH, O 2 −, h+, and 1O 2) enhanced the anti-interference ability. The self-degradation analysis showed that FePc had obvious self-degradation in the photo-Fenton process, while CNFP had no self-degradation. Furthermore, the CNFP/H 2 O 2 photo-Fenton system was carefully evaluated by pH effect, ions effect, toxicity assessment, and cycling experiments, revealing its application potential in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

• A novel benzene ring modified g-C 3 N 4 photocatalyst is successfully synthesized. • BCNNS exhibits excellent light response and the separation of charge carriers. • The modification of benzene ring can promote the activation of molecular oxygen. • BCCNS shows improved photocatalytic activity for OTC degradation. Popular graphitic carbon nitride (g-C 3 N 4) photocatalyst always faces the problems of weak visible light absorption and fast recombination of photogenerated electron-hole pairs. Herein, a novel benzene ring modified g-C 3 N 4 nanosheet (BCNNS) was synthesized by a simple calcination method. The degradation rate of oxytetracycline by BCNNS under visible light can reach 72% (within 60 min), significantly higher than that of the unmodified g-C 3 N 4 nanosheet (50%). And the degradation rate constant of BCNNS is 0.025 min−1, which is 2.1 times higher than that of g-C 3 N 4 (0.012 min−1). The improvement in the photocatalytic degradation performance can be attributed to the introduction of benzene ring, which can significantly broaden the light absorption range and intensify. In addition, the introduction of benzene ring can adjust the original electronic structure, thereby effectively suppressing the recombination of electron-hole pairs. Furthermore, density functional theory (DFT) calculations demonstrate that the introduction of benzene ring can significantly promote the surface adsorption of molecular oxygen and promote the transfer of electrons to molecular oxygen. This demonstrates that the embedded benzene ring can effectually advance the activation of molecular oxygen, which also well confirms that O 2 − and 1O 2 are the main active species in the system of BCNNS photocatalytic degradation of oxytetracycline. This study reveals that benzene ring modified g-C 3 N 4 has great potential in environmental purification, and provides a promising strategy for the removal of stubborn water contaminants. [ABSTRACT FROM AUTHOR]

The increasingly serious pollution of antibiotics brings an enormous threat to the ecological environment and human health. Graphite phase carbon nitride (g-C 3 N 4), as a popular photocatalytic material, is widely used in photocatalytic degradation of antibiotics in water. In order to make up for the shortage of g-C 3 N 4 monomer, CeO 2 /N-doped g-C 3 N 4 (CeNCN) composite photocatalysts co-modified with nitrogen doping and CeO 2 loading were designed and synthesized with the idea of expanding visible light absorption and promoting photogenerated carrier separation. CeNCN exhibits excellent photodegradation performance, the removal rate of tetracycline reached 80.09% within 60 min, which is much higher than that of g-C 3 N 4 (CN) and N-doped g-C 3 N 4 (NCN); and the quasi-first-order degradation rate constant is 0.0291, which is 7.86 and 2.29 times higher than CN and NCN. Electron spin resonance and free radical trapping experiments confirmed that h+, O 2 − and OH are the active substances in the photocatalytic system. After 5 cycles, the degradation efficiency of tetracycline still exceeds 75%, which indicates that CeNCN has good stability. This work proves that N-doping and CeO 2 loading can effectively broaden the photoresponse range of g-C 3 N 4 , facilitate the separation of photogenerated electron-hole pairs, and provide a reference for the construction of g–C 3 N 4 –based photocatalyst with high-efficiency photodegradation activity. [Display omitted] • CeO 2 /N-doped g-C 3 N 4 (CeNCN) photocatalyst was successfully first synthesized. • CeNCN exhibits excellent light response and the separation of charge carriers. • CeNCN exhibits significantly enhanced photocatalytic activity for TC degradation. • The proposed photocatalytic mechanism toward CeNCN photocatalyst is illustrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coordinative Fe-N x improved the catalytic ability of FeOCN for photo-Fenton process. • The consumption of H 2 O 2 was reduced in the photo-Fenton process over FeOCN. • FeOCN showed high catalytic performance for tetracycline degradation. • The improved charge separation favored Fe(III)/Fe(II) conversion. • FeOCN exhibited wide applicable pH range and anti-interference ability to anions. Tetracycline (TC) antibiotics have been widely used over the past decades, and their massive discharge led to serious water pollution. Photo-Fenton process has gained ever-increasing attention for its excellent oxidizing ability and friendly solar energy utilization ability in TC polluted water treatment. This work introduced coordinative Fe into oxygen-enriched graphite carbon nitride (OCN) to form FeOCN composites for efficient photo-Fenton process. Hemin was chosen as the source to provide the source of coordinative Fe-N x groups. The degradation efficiency of TC reached 82.1 % within 40 min of irradiation, and remained 76.9 % after five runs of reaction. The degradation intermediates of TC were detected and the possible degradation pathways were gained. It was found that h+, OH, and O 2 − played major roles in TC degradation. Notably, the photo-Fenton performance of FeOCN was stable in highly saline water or strong acid/base environment (pH 3.0–9.0). Besides, H 2 O 2 can be generated in-situ in this photo-Fenton process, which is favorable for practical application. It can be anticipated that the coordinative FeOCN composites will promote the application of photo-Fenton oxidation process in TC polluted water treatment. [ABSTRACT FROM AUTHOR]

Optimising advanced oxidation processes (AOPs) by creating oxygen vacancies (OVs) on metal oxides via doping with different ions to improve catalyst activity is currently a significant research field. OVs produced by doping have the potential to substantially reduce the reaction energy barrier, and impact the reaction products with high selectivity. However, there is currently a lack of reviews on the utilization of dopant ions to induce OVs and the application of dopant-induced OVs in AOPs. This paper provides a systematic overview of the selection of dopant ions for the construction of OVs by doping. Additionally, we present two theoretical explanations highlighting the ability of doping to obtain OVs, explaining how doping can be used to design catalysts with ample OVs. Next, we methodically illustrate the kinetic and thermodynamic interactions between OVs and dopant ions. We also discuss the direct and indirect destruction of OVs by environmental factors that influence dopant elements in AOPs. Finally, the paper concludes with a detailed account of the application of OVs induced by doping in typical advanced oxidation techniques, such as Fenton-like oxidation, activated persulfate oxidation, catalytic ozonation, photocatalysis and electrochemical oxidation. Additionally, potential avenues of future research are suggested. [ABSTRACT FROM AUTHOR]

[Display omitted] • A flower-like CdS/K 2 Ta 2 O 6 S-scheme heterojunction was prepared. • The S-scheme charge transfer mechanism between CdS and K 2 Ta 2 O 6 was revealed. • Excellent ability for photocatalytic H 2 O 2 production from water and air. • The route and mechanism of the photocatalytic H 2 O 2 production were proposed. The hydrogen peroxide (H 2 O 2) production using solar energy is of great significance in chemical industry and environmental remediation. However, this technique requires that photocatalysts have efficient charge separation and migration efficiency. Herein, we designed a flower-like CdS/K 2 Ta 2 O 6 (CdS/KTO) S-scheme heterojunction with promoted charge separation and migration by a facile two-step hydrothermal strategy. The CdS/KTO photocatalyst exhibited an outstanding performance with a H 2 O 2 production rate of 160.89 μmol g−1 h−1 without using any sacrificial agents and adding additional O 2. The combination of the in situ irradiated X-ray photoemission spectroscopy (XPS), electron paramagnetic resonance (EPR) and density functional theory (DFT) calculations revealed that the formation of an S-scheme heterojunction between CdS and KTO could greatly promote the separation of photogenerated electron-hole pairs toward efficient H 2 O 2 production. This work provides insights for the charge transfer mechanism of S-scheme heterojunction and an innovative stratagem for green, energy-saving and sustainable H 2 O 2 production. [ABSTRACT FROM AUTHOR]

[Display omitted] • The advantages and features of COFs for confining ADMCs are summarized. • The design strategies for COFs and derivatives confined ADMCs are elaborated. • Electrocatalytic application of COFs and derivatives confined ADMCs are expounded. • The existing challenges and prospect are suggested. Atomically dispersed metal catalysts (ADMCs), a kind of metal species in the form of isolated atoms, have already become a new research front in heterogeneous catalysis. Generally, ADMCs are confined on supports, offering a better opportunity to optimize the catalytic performance via making use of metal-support interface interaction. Moreover, the electronic state and coordination structure of ADMCs can be regulated by the coordinated atoms from supports, thereby affecting the interaction between catalysts and substrates. Hence, the support plays a decisive role in the coordination structure, thereby determining the catalytic performance. Recently, covalent organic frameworks (COFs) exhibit enormous potential for confining ADMCs, featuring the outstanding properties of predictable structure, adjustable pore size, and tailored functionality. Here, this review not only elaborates the advantages and features of COFs for confining ADMCs, but also highlights the design strategies of COFs and derivatives confined ADMCs. Besides, we showcase the recent advance in electrocatalytic energy conversion and storage of COFs and derivatives confined ADMCs. Finally, the current problems, feasible strategies, and future expectations for the practical applications of COFs and derivatives anchored ADMCs are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal-organic frameworks derived low-cost Cu-doped Cu-Co 3 O 4 /NF is simply prepared. • High ammonia yield rate and FE are obtained under ultra-low nitrate concentrations. • The introduction of Cu promotes the surface-to-interior charge transfer and intrinsic activity. • The results of In-situ FTIR and DFT reveal atomic hydrogen reduction pathway. • The synergistic effect of Cu and Co suppresses the HER and drops the free energy barriers of rate determining step. The electrochemical reduction of nitrate to ammonia represents a potential approach for the valorization of waste, offering the dual benefit of mitigating various environmental concerns and concurrently yielding the valuable product of ammonia. However, on the way to its further application, the lacking of low-cost and efficient electrocatalysts under low nitrate concentrations is still one pressing issue because of the intense hydrogen evolution reaction (HER) competition and many by-products. Herein, metal–organic frameworks (MOF) derived low-cost Cu-Co 3 O 4 /NF exhibits excellent electrocatalytic activity in the low nitrate concentrations (2 mmol/L), attaining the ammonia yield rate of 0.076 mmol h−1 cm−2 and 92.4 % Faradic efficiency at −0.53 V vs. RHE. The combined results of In-situ FTIR and theoretical calculation reveal the atomic hydrogen reduction pathway, decrease in free energy of intermediate reactions and inhibition of HER of Cu-Co 3 O 4 /NF. This work introduces one economical, efficient and simple strategy and further demonstrates the superior effect of MOF derivatives in fascinating low nitrate concentration reduction to ammonia. [ABSTRACT FROM AUTHOR]

[Display omitted] • The strategies for improving the PEC performance of carbon-based semiconductor photoelectrocatalysts are elaborated. • The latest applications of carbon-based semiconductor photoelectrocatalysts in organic pollutant removal are thoroughly summarized. • The mechanism of carbon-based materials improving the PEC efficiency and their roles in PEC systems are emphasized. • The profound insights into the future development of carbon-based semiconductor photoelectrocatalysts are proposed. Photoelectrocatalysis (PEC) technology has attracted broad interest due to its great application potential in pollutant removal and energy production. However, the high recombination of photogenerated electron-hole pairs, low utilization efficiency of solar energy, and limited reaction area are still the main obstacles that limit the practical applications of PEC. Carbon-based materials with unique and excellent properties are widely coupled with semiconductors to prepare composite photoelectrocatalysts to address the above problems. Carbon-based materials can serve as supporting materials, conductive substrates, electron transfer media, photosensitizers, and stabilizers to greatly improve the photoelectrocatalytic performance of semiconductors. Meanwhile, carbon-based materials can exert semiconductor properties to generate electron-hole pairs or construct heterojunctions with semiconductors to efficiently promote charge separation. In this review, a comprehensive summary is given to introduce synthetic methods and improvement strategies of carbon-based material/semiconductor composite photoelectrocatalysts, as well as their latest applications in the removal of organic pollutants. Especially, the roles of carbon-based materials in the PEC process are highlighted. Finally, current challenges and prospects are put forward. We do hope that this article can outline the recent advances and provide new insights for the future development of carbon-based semiconductor photoelectrocatalysts applied in water treatment. [ABSTRACT FROM AUTHOR]

Photocatalysis is currently a hot research field, which provides promising processes to produce green energy sources and other useful products, thus eventually benefiting carbon emission reduction and leading to a low-carbon future. The development and application of stable and efficient photocatalytic materials is one of the main technical bottlenecks in the field of photocatalysis. Perovskite has excellent performance in the fields of photocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), carbon dioxide reduction reaction (CO 2 RR), organic synthesis and pollutant degradation due to its unique structure, flexibility and resulting excellent photoelectric and catalytic properties. The stability problems caused by perovskite's susceptibility to environmental influences hinder its further application in the field of photocatalysis. Therefore, this paper innovatively summarizes and analyzes the existing methods and strategies to improve the stability of perovskite in the field of photocatalysis. Specifically, (i) component engineering, (ii) morphological control, (iii) hybridization and encapsulation are thought to improve the stability of perovskites while improving photocatalytic efficiency. Finally, the challenges and prospects of perovskite photocatalysts are discussed, which provides constructive thinking for the potential application of perovskite photocatalysts. [Display omitted] • Propose method of perovskites modification to combine high stability and efficiency. • Apply methods of improving the stability of perovskites in photocatalysis. • The challenges and prospects for more stable perovskite catalysts are presented. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY), a rising star of 2D carbon allotropes with one‐atom‐thick planar layers, has achieved the coexistence of sp‐ and sp2‐hybridized carbon atoms in a 2D planar structure. In contrast to the prevailing carbon allotropes, GDY possesses Dirac cone structures, which endow it with unique chemical and physical properties, including an adjustable inherent bandgap, high‐speed charge carrier transfer efficiency, and excellent conductivity. Additionally, GDY also displays great potential in photocatalysis, rechargeable batteries, solar cells, detectors, and especially electrocatalysis. In this work, various GDY‐supported electrocatalysts are described and the reasons why GDY can act as a novel support are analyzed from the perspective of molecular structure, electronic properties, mechanical properties, and stability. The various electrochemical applications of GDY‐supported electrocatalysts in energy conversion such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, overall water splitting, and nitrogen reduction reaction are reviewed. The challenges facing GDY and GDY‐based materials in future research are also outlined. This review aims at providing an in‐depth understanding of GDY and promoting the development and application of this novel carbon material. [ABSTRACT FROM AUTHOR]

At present, environmental pollution caused by refractory organic pollutants becomes more serious. Semiconductor-based photocatalysis technology, an idea and continuable technology by solar-light-driven, is widely employed to address this situation. Here, oxygen-vacancy rich WO 3 decorated monolayer Bi 2 WO 6 nanosheet composite as an atomic scale heterojunction with high active species and ultrafast charge carrier transfer was rationally constructed. The atomic scale V o -WO 3 /Bi 2 WO 6 composite displayed remarkable photoactivity comparing with pristine V o -WO 3 and Bi 2 WO 6 ultrathin nanosheet, and about 79.5% of Ciprofloxacin can be degraded within 120 min under visible light irradiation when 40 mg of photocatalyst was added into CIP solution (10 mg/L). The promoted photoactivity can be ascribed to the following points: (1) the composite possesses enormous surface pit, thereby expanding the species surface area and exposing more active site to promote antibiotic absorption; (2) the presence of abundant oxygen vacancy can facilitate the formation of more electrons, which can be consumed by adsorbed molecular oxygen to produce superoxide radical, thereby accelerating degradation organic pollutant; (3) ultrathin V o -WO 3 nanosheet decorated monolayer Bi 2 WO 6 can shorten the charge carrier transfer distance and enlarge interface contact area, then ensuring remarkable photodegradation efficiency. The reasons for promoted photodegradation efficiency were elaborated based on experiments results and ESR analysis and the degradation pathways of CIP were recorded via [(LC-MS)/MS]. After 5 run for the degradation of CIP, V o -WO 3 /Bi 2 WO 6 composite also exhibited great photodegradation efficiency, thereby demonstrating its excellent stability and reusability. [ABSTRACT FROM AUTHOR]

[Display omitted] • UiO-66-SO 3 H/Fe(1:1)-800 exhibited high tetracycline degradation efficiency. • The influence of operating parameters on tetracycline degradation was analyzed. • It exhibited good stability and potential for wastewater treatment applications. • Mechanism of TC degradation by heterogeneous electro-Fenton process was proposed. Designing efficient heterogeneous electro-Fenton (HEF) catalysts for in-situ H 2 O 2 generation and organic pollutant degradation in water has become a hot research topic. In this study, a series of novel UiO-66-SO 3 H/Fe(x)-800 materials were successfully prepared by carbonizing sulfonic acid metal-organic frameworks (UiO-66-SO 3 H) doped with iron for tetracycline (TC) HEF degradation. The catalytic performance of UiO-66-SO 3 H/Fe(x)-800 was evaluated by comparing different HEF systems, and the effects of different operating parameters and co-existing substances were investigated. The results indicated that UiO-66-SO 3 H/Fe(1:1)-800 displayed excellent performance for TC degradation over a broad pH range, with an optimal TC degradation efficiency of 90.10% in 90 min and a low energy consumption of 4.39 kWh/kg/TOC. Furthermore, the superior stability and reusability of this catalyst were proved in continuous cycling experiments with low iron leaching (<1.000 ug/L). The mechanism exploration demonstrated that TC was mainly oxidized by ‧OH and 1O 2. In addition, iron-doped porous carbon carrier improved the utilization rate of H 2 O 2 and accelerated the regeneration of Fe2+, which played an important role in the HEF process. The HEF system based on UiO-66-SO 3 H/Fe(1:1)-800 also exhibited satisfactory performance when treating actual water samples, presenting broad application prospects. [ABSTRACT FROM AUTHOR]

As a rising branch of advanced oxidation processes, persulfate activation has attracted growing attention. Unlike catalysts that have been widely studied, the selection of persulfate is previously overlooked. In this study, the affecting factors of persulfates were studied. The effect of target pollutant properties on superior persulfate species (the species with a higher degradation efficiency) was investigated by multiwalled carbon nanotube (MWCNT)/persulfate catalytic systems. Innovatively, the E HOMO (or vertical ionization potential (VIP)) value of the target pollutant was proposed to be an index to judge the superior persulfate species, and the threshold is VIP= 6.397–6.674 eV, E HOMO = −8.035∼− 7.810 eV, respectively. To be specific, when the VIP of phenolic compounds is higher (or E HOMO of phenolic compounds is lower) than the threshold, the catalytic performance of peroxymonosulfate would be higher than that of peroxydisulfate. Moreover, the effects of coexisting cations on peroxydisulfate superior species were further investigated. It was illustrated that the hydrated cation radius of coexisting cations would influence the pollutant degradation efficiency under some circumstances. This study provides a new approach to improve the cost of persulfate activation systems and promotes the underlying downstream application of persulfate activation systems. [Display omitted] • The properties of target pollutant would influence the superior persulfate species. • E HOMO and VIP of pollutant can be applied to judge the superior persulfate species. • Co-existing cations of PDS showed little effect on heterogeneous catalysis. • The superior peroxydisulfate species were not affected by the target pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high catalytic activity catalyst was prepared by a one-step calcination method. • Ni 4.60 CN/PMS system performed well over a wide pH and common interferences. • The Ni-N 4 -C active site of Ni 4.60 CN mediated electron transfer pathway. • Pollutants could be selectively degraded in the Ni 4.60 CN/PMS system. Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) is a hopeful method for organic pollutants degradation. However, conventional AOPs often suffer from various disturbances in applications, such as organic matter, inorganic ions, pH, etc. Herein, a novel Ni(Ⅱ)-doped g-C 3 N 4 (Ni 4.60 CN) catalyst with Ni-N 4 -C structure was prepared, which exhibited outstanding PMS activation ability. The Ni-N 4 -C active sites facilitated the electron transfer from pollutants to PMS and achieving high selectivity toward pollutant degradation. Then, integrating experimental and theoretical results, the origin of this selectivity was revealed, indicating that organic pollutants with low vertical ionization potential (VIP), high the highest occupied molecular orbital energy (E HOMO), and low potential differences between organics and Ni 4.60 CN (marked as E PD) are more beneficial to be degraded. This study unravels the electron transfer mechanism induced by Ni-N 4 -C sites in Ni 4.60 CN /PMS activation system and provides a comprehensive insight into the selective oxidation behavior of various pollutants. [ABSTRACT FROM AUTHOR]

Heterogeneous Fenton-like process based on H 2 O 2 activation has been widely tested for water purification, but its application still faces some challenges such as the use of high doses of chemicals (including catalysts and H 2 O 2). Herein, a facile co-precipitation method was utilized for small-scale production (∼50 g) of oxygen vacancies (OVs)-containing Fe 3 O 4 (V o -Fe 3 O 4) for H 2 O 2 activation. Experimental and theoretical results collaboratively verified that H 2 O 2 adsorbed on the Fe site of Fe 3 O 4 tended to lose electrons and generate O 2 •-. While the localized electron from OVs of V o -Fe 3 O 4 could assist in donating electrons to H 2 O 2 adsorbed on OVs sites, this allowed more H 2 O 2 to be activated to •OH, which was 3.5 folds higher than Fe 3 O 4 /H 2 O 2 system. Moreover, the OVs sites promoted dissolved oxygen activation and decreased the quenching of O 2 •- by Fe(III), thus promoting the generation of 1O 2. Consequently, the fabricated V o -Fe 3 O 4 achieved much higher oxytetracycline (OTC) degradation rate (91.6%) than Fe 3 O 4 (35.4%) at a low catalyst (50 mg/L) and H 2 O 2 dosage (2 mmol/L). Importantly, further integration of V o -Fe 3 O 4 into fixed-bed Fenton-like reactor could effectively eliminate OTC (>80%) and chemical oxygen demand (COD) (21.3%∼50%) within the running period. This study provides promising strategies for enhancing the H 2 O 2 utilization of Fe mineral. [Display omitted] • A facile strategy was examined to synthesize Fe 3 O 4 with oxygen vacancies. • H 2 O 2 tended to lose e- on Fe sites of Fe 3 O 4 and gain e- on OVs sites of V o -Fe 3 O 4. • The OVs sites promoted dissolved oxygen activation and conversion of O 2 •- to 1O 2. • V o -Fe 3 O 4 /H 2 O 2 system performed well in both batch and continuous-flow reactor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Green and facile α-FeOOH/GBC Fenton-like systems were constructed to remove OTC. • The performance of α-FeOOH/GBC enhanced with the increase of GBC's graphitization. • The major role of GBC was to facilitate the reaction between H 2 O 2 and Fe(III). • Donated eletrons for fasting Fe(III)/Fe(II) redox cycle was another role of GBC. • O 2 - and 1O 2 were identified as the predominant ROS for OTC degradation. Due to the contradiction between attractive properties and undesirable Fenton-like catalytic performance of iron minerals, how to enhance their Fenton-like catalytic activity is a critical but challenging issue. Here, we took an eco-friendly approach to improve the Fenton-like catalytic capacity of goethite (α-FeOOH) by loading it on graphitized biochar (GBC), and the results indicated that the existence of GBC could successfully facilitate the oxytetracycline (OTC) removal. The degradation rate constant of α-FeOOH/GBC-10 composite was approximately 2.1 times higher than that of α-FeOOH. GBCs with different graphitization degrees were obtained by adjusting the pyrolysis temperature. Interestingly, the improvement of catalytic activity of α-FeOOH/GBC was well correlated with the graphitization degree of GBC, and the graphitized structures (sp2-C) and functional group (C O) in GBC could expedite the blocked Fe(III)/Fe(II) cycling by speeding up the electrons transfer from H 2 O 2 to α-FeOOH and donating electrons to Fe(III). In addition, the electron spin resonance and quenching experiments demonstrated that OTC removal was attributed to the joint action of •OH, O 2 −, and 1O 2. This study sheds light on the possible role of GBC in Fenton-like reactions based on iron minerals and thus, lays the groundwork for the rational construction of more efficient Fenton-like catalytic systems. [ABSTRACT FROM AUTHOR]

• Metal-carbon hybrid materials are promising catalysts for PS-AOPs. • Metal-carbon interaction favors reduced metal leaching and improved catalysis. • The modulation strategies for changing PS activation mechanism are elaborated. • The existing challenges and future research directions are summarized. Proper wastewater treatment has always been the focus of human society, and many researchers have been working to find efficient and stable wastewater treatment technologies. Persulfate-based advanced oxidation processes (PS-AOPs) mainly rely on persulfate activation to form reactive species for pollutants degradation and are considered to be one of the most effective wastewater treatment technologies. Recently, metal-carbon hybrid materials have been diffusely used for PS activation because of their high stability, abundant active sites, and easy applicability. Metal-carbon hybrid materials can successfully overcome the shortcomings of onefold metal catalysts and carbon catalysts by combing the complementary advantages of the two components. This article reviews recent studies about metal-carbon hybrid materials-mediated PS-AOPs for wastewater decontamination. The interactions of metal and carbon materials, as well as the active sites of metal-carbon hybrid materials, are introduced first. Then, the application and mechanism of metal-carbon hybrid materials-mediated PS activation are presented in detail. Lastly, the modulation methods of metal-carbon hybrid materials and their tunable reaction pathways were discussed. The prospect of future development directions and challenges is proposed to facilitate metal-carbon hybrid materials-mediated PS-AOPs to take a step further for practical application. [Display omitted] [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) with unique physical and chemical properties are composed of metal ions/clusters and organic ligands, including high porosity, large specific surface area, tunable structure and functionality, which have been widely used in chemical sensing, environmental remediation, and other fields. Organic ligands have a significant impact on the performance of MOFs. Selecting appropriate types, quantities and properties of ligands can well improve the overall performance of MOFs, which is one of the critical issues in the synthesis of MOFs. This article provides a comprehensive review of ligand design strategies for functional MOFs from the number of different types of organic ligands. Single-, dual- and multi-ligand design strategies are systematically presented. The latest advances of these functional MOFs in environmental applications, including pollutant sensing, pollutant separation, and pollutant degradation are further expounded. Furthermore, an outlook section of providing some insights on the future research problems and prospects of functional MOFs is highlighted with the purpose of conquering current restrictions by exploring more innovative approaches. [Display omitted] • Three ligand design strategies for functional MOFs are systematically presented. • The recent advances of functional MOFs in environmental applications are presented. • The mechanisms of functional MOFs in environmental applications are discussed. • Problems and challenges of functional MOFs by ligand design in future research are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous bimetal-doped FTCN were successfully synthesized. • FTCN exhibited excellent photo-Fenton activity under visible light. • The important role played by bimetals in catalysts was investigated by DFT method. • The photo-Fenton mechanism of FTCN was discussed in deep. In this study, we synthesized Fe and Ti co-doped graphitic carbon nitride (FTCN) with high catalytic ability by a two-step calcination method. The photoelectrochemical results indicated that FTCN possessed a reduced bandgap and promoted photocarrier transfer efficiency, which enables FTCN excellent performance on oxytetracycline (OTC) degradation (90 % within 10 min). The main reactive oxygen species and the intermediates of OTC in the photo-Fenton process were obtained. Experimental data and density functional theory (DFT) were combined to explore the mechanism in depth. Interestingly, it was found that Fe and Ti respectively act as the main activation centers of H 2 O 2 and O 2 , while few oxygen-containing metal active sites participate in the activation process. The synergistic effect of bimetallic doping plays a significant role in enhancing the photo-Fenton catalytic performance. Hopefully, a new approach to design highly efficient multifunctional catalysts or dual single-atom catalysts can be developed. [ABSTRACT FROM AUTHOR]

• Hemin derived iron and nitrogen-doped carbon catalyst exhibited high ciprofloxacin degradation and mineralization efficiency. • KHCO 3 -MgO dual-porogen improved the porous characteristics and exposed the iron sites. • Based on degradation intermediates analysis, a possible degradation pathway of CIP was proposed. • It exhibited good stability and potential for treatment of organic pollutants in wastewater. Heterogeneous electro-Fenton (HEF) technology has become a hot topic for degradation of organic pollutants in water. However, it remains a challenge to design effective catalysts for high H 2 O 2 utilization and pollutant degradation. In this work, we explored a novel iron and nitrogen-doped carbon catalyst derived from hemin (Fe-N-C) using KHCO 3 -MgO as dual-porogen. The results suggested that the KHCO 3 -MgO dual-porogen could not only improve the porous characteristics of catalyst, but also expose iron sites and change the proportion of nitrogen species. The pollutant degradation results demonstrated that the Fe-N-C-700/HEF system exhibited high ciprofloxacin degradation efficiency of 93.82% within 50 min and mineralization efficiency of 87.87% within 90 min by low energy consumption. Moreover, cycle experiments and metal ions leaching experiments revealed that the catalyst had good stability and recyclability. Electron spin resonance (ESR) test and radical capturing experiment showed that •OH was the dominant active species in this HEF system. In addition, the Fe-N-C-700/HEF system achieved satisfactory performance in the treatment of real water matrix, indicating the possibility for practical application in wastewater purification. [ABSTRACT FROM AUTHOR]

• A synthesis temperature gradient was set to regulate the defect level of S-OMC. • Removal of sulfur heteroatom could bring more carbon defects. • A structure-activity relationship between defects and 1O2 production was built. • CIP removal reached 85.84% under unadjusted pH and slight S-OMC-1000. • S-OMC-1000/PDS system performed well in the presence of common interferents. The carbon-catalyzed persulfate-based advanced oxidation process (PS-AOP) has recently received much focus owing to the green, economical, and sustainable nature of carbon catalysts. In this study, sulfur-doped ordered mesoporous carbons (S-OMCs) were utilized to activate peroxydisulfate (PDS) for ciprofloxacin (CIP) removal. A synthesis temperature gradient was set to regulate the defect level of S-OMCs, since the thermal decomposition of oxygen- and sulfur-containing groups at different temperatures could release S and O and then create defects. In all S-OMCs/PDS systems, 1O 2 dominated CIP degradation. Interestingly, a high linear correlation (R2 = 0.9091) between defect level and 1O 2 yield was found, confirming the structure-activity relationship between defects and 1O 2 generation. Moreover, the impacts of several important reaction conditions and water matrix on S-OMC-1000/PDS activation system were surveyed. In the S-OMC-1000/PDS activation system, CIP removal could attain 85.84% under the condition of unadjusted pH (pH = 5.3) and small amount of S-OMC-1000 (50 mg/L). The S-OMC-1000/PDS activation system also exhibited relatively stable or even better performance in the presence of common inorganic anions and natural organic matter (NOM), manifesting its good potential for practical applications. In addition, the reusability of S-OMC-1000 was investigated. This study provides a practical and high-efficiency way for decontaminating antibiotic-polluted water, and gives an alternative approach for identifying the active site of catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

Recently, photo-Fenton technology has been widely used to degrade tetracycline (TC) because of its great efficiency and wide application range. Herein, Fe–Ni layered double hydroxides (FeNi-LDH)/Ti 3 C 2 photo-Fenton system was constructed in this study. The results showed the introduction of Ti 3 C 2 solved some problems of FeNi-LDH such as poor conductivity, easy aggregation, and high recombination rate of photoelectron. Benefiting from these advantages, FeNi-LDH/Ti 3 C 2 exhibited excellent TC removal rate of 94.7% while pure FeNi-LDH was only 54%. Besides, FeNi-LDH/Ti 3 C 2 possessed strong pH tolerance (2–11) and the removal efficiency was still up to 82% after the four-cycle experiment. Furthermore, the quenching experiments revealed the reaction mechanism, where ∙OH and ·O 2 − were the primary active radicals for degrading TC. Last, the results of the simulated wastewater treatment and the inorganic ion interference tests showed that FeNi-LDH/Ti 3 C 2 possessed practical application potential. In brief, this study shows that FeNi-LDH/Ti 3 C 2 can offer a certain theoretical basis for the actual development of hydrotalcite in heterogeneous photo-Fenton systems. [Display omitted] • A novel material FeNi-LDH/Ti 3 C 2 was successfully prepared by a facile method. • The incorporation of Ti 3 C 2 enhanced the photogenerated carrier separation. • The degradation efficiency of TC increased by 40% after introduce Ti 3 C 2. • FeNi-LDH/Ti 3 C 2 photo-Fenton system possessed great application prospect. • The possible mechanism and degradation pathways of TC were illustrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen vacancy assisted Fenton-like catalysts were used to degrade ciprofloxacin. • Mn-CuO/OVs/H 2 O 2 system has good buffering ability to pH. • Cu(III) was mainly responsible for the degradation of ciprofloxacin. • 1O 2 , ∙OH and ∙O 2 – play minor role in ciprofloxacin degradation. Traditional Fenton reaction is limited by the problem of free radical scavenging and always requires pre-acidification, which seriously hinders its practical application. In this study, an oxygen vacancy (OVs) assisted Fenton-like catalyst (Mn-CuO) was designed to degrade ciprofloxacin (CIP). Results showed that Mn 10 CuO exhibited 3 times decomposition rate of H 2 O 2 than that of CuO, and can make decent performances under a wide pH ranges (pH = 3.01–10.00). This can be ascribed to the Cu-Mn binary synergism and formation of OVs after addition of Mn2+, which not only improved the adsorption capacity of catalyst, but also promoted H 2 O 2 activation. Moreover, different radical scavenging experiments and characterization shows that Cu(III) rather than ·OH dominated the degradation process in Mn 10 CuO/H 2 O 2 system. The degradation intermediates were analyzed by LC-MS, and proposed the possible degradation pathways. Moreover, this system can work efficiently in tap water, river water as well as lake water without adjusting pH. This work indicates that it is an efficient strategy to constructing Fenton-like systems by using surface defect engineering to develop efficient catalyst. [ABSTRACT FROM AUTHOR]

Peroxymonosulfate (PMS)-based advanced oxidation processes for wastewater treatment have received extensive attention in the past years. Here, a novel Mn, Ce co-modified g-C 3 N 4 (MnCe-CN) composite was successfully synthesized by one-step pyrolysis for activating PMS. The physical and chemical characterization of MnCe-CN/PMS was conducted, indicating that Mn and Ce were evenly distributed on g-C 3 N 4 and existed in the form of Mn-N structure and CeO 2 , respectively. The MnCe-CN/PMS system could effectively degrade pollutants such as acetaminophen (ACT), methylparaben (MeP), p -nitrophenol (PNP), and 2,4-dichlorophenol (2,4-DCP). Among them, 2,4-DCP could be rapidly degraded, reaching 100% within 30 min. The masking experiments and electrochemical testing results revealed that 2,4-DCP was degraded via superoxide radicals (O 2 ˙ˉ), singlet oxygen (1O 2), and electron transfer path. The cyclic experiments and real water treatment experiments testified that the oxidative system had excellent stability and applicability. This study provides a facile synthetic method to fabricate bimetallic co-modified g-C 3 N 4 for the enhancement of PMS activation. [Display omitted] • A facile synthesis way for Mn and Ce co-modified g-C 3 N 4 was developed. • Mn(Ⅱ)/Mn(Ⅲ) in the N-pot was proved to be the main active site. • The MnCe-CN composites had excellent stability and applicability. • O 2 ˙ˉ, 1O 2 played a major role in the degradation of 2,4-DCP. [ABSTRACT FROM AUTHOR]

[Display omitted] • The rational design of photoelectrocatalyst is emphasized. • The recent advances of PEC in environmental applications are presented comprehensively. • The working mechanisms of photoelectrocatalysts in PEC system are discussed. • The challenges and prospects for PEC in environmental applications are put forward. Harmful contaminants and microorganisms in the environment have threatened ecological security and human health. Detecting and removing these pollutants with a simple and high-efficiency method is significantly essential. Compared to conventional sensing and eliminating routes, photoelectrocatalysis (PEC), as a recently arisen pathway, combines the advantages of photocatalysis and electrocatalysis, and unfolds a novel platform. The PEC activity is strongly linked to the composition and morphology characteristics of photosensitive semiconductor. Hence, much attention has been paid to the rational fabrication and modification of high-efficiency photoelectrocatalysts. Herein, we offer an all-around review on the design strategies of photoelectrocatalysts, including ion doping and constructing heterojunctions as well as some other methods like vacancy induction, surface treatment, crystal plane regulation, size and morphology control. The recent advances for environmental applications of these photoelectrocatalysts in PEC system involving pollutants sensing, pollutants removal, and microbial inactivation are expounded. Besides, the functional mechanisms and performance assessment of the established PEC system are discussed. More importantly, the challenges and prospects of future research are put forward. This review makes clear the application of PEC in the field of environment, and provides unique insights for the future research direction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-Co LDH/C, O co-doped g-C 3 N 4 2D/2D heterojunction has been first fabricated. • The modification of 2-methylimidazole enhanced photoconversion efficiency. • 2D/2D heterojunction exhibits excellent molecular oxygen activation. • The formed charge carrier transfer pathway promotes photoelectron transfer. • 2D/2D heterojunction possesses weakened surface charge carrier recombination. Molecular oxygen is a green and low-cost oxidant, which can be activated to produce reactive oxygen species by solar-light-driven photocatalysis. Here, Ni-Co LDH infused C, O co-doped g-C 3 N 4 two-dimensional (2D) ultrathin nanosheet was prepared by a simple thermal polymerization coupling hydrothermal method. The molecular oxygen activation was estimated by the quantitative determination of •O 2 − and 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation. 2D/2D heterojunction exhibits impressive photocatalytic performance. The arrestive activation efficiency is derived from the regulated energy band position, the broadened solar light absorption range, and the enhanced photoexcited electron transfer. Benefitting from these merits, the surface charge transfer efficiency of 2D/2D heterojunction is promoted to 51.3% from 14.3% (g-C 3 N 4). The surface recombination rate constant is reduced to 0.0011 s−1 from 0.0042 s−1 (g-C 3 N 4). The feasible photocatalytic mechanism for molecular oxygen activation is expounded based on experimental analysis. [ABSTRACT FROM AUTHOR]

• The characteristics of BP, h-BN, g-C 3 N 4 , graphene, and COFs are introduced. • The recent advances in element doping and heterojunction constructing are reviewed. • Organic amendment, hydroxyl modification, and dye sensitization are introduced. • The applications in HER, CO 2 RR, NRR, OER, and ORR are concluded. Semiconductor photocatalysis has been recognized as a feasible strategy for effective utilization of solar power to alleviate the energy shortage and environmental crisis. Efficient photocatalytic process over two dimensional (2D) ultrathin nanomaterial is one of the most paramount technologies for solving these problems. In this review, we begin with a brief introduction of five nonmetal-based 2D ultrathin nanomaterials (including black phosphorus (BP), hexagonal boron nitride (h-BN), covalent organic frameworks (COFs), graphene, and polymeric graphitic carbon nitride (g-C 3 N 4)), which mainly discusses the special characteristics of these materials. And then, as the main content of the article, recent advances of optimizing strategies for these five 2D materials are reviewed from the aspects of element doping and construction of heterojunction. We subsequently discuss the new strategies that may be effective for future optimization. Furthermore, the applications of nonmetal-based 2D photocatalysts in energy such as H 2 evolution, CO 2 reduction, N 2 fixation, O 2 evolution, and O 2 reduction are concluded. Finally, conclusions and outlooks are given for future potential directions. [ABSTRACT FROM AUTHOR]

• The roles of biochar in resource recovery from water are overviewed. • Resource recovery of components, water, and energy using biochar are discussed. • Efficiency enhancement strategies for resource recovery by biochar are evaluated. • The value and practical re-application of recovered resources are summarized. • The developments of biochar-based resource recovery are proposed. Over the past few decades, the shortage of water resource has prompted a shift in human concept about waste water: from waste to valuable resource. Utilizing wastewater can not only mitigate water scarcity, but also provide an opportunity for nutrient and energy recovery, further offsetting part of the exploitation of valuable resources. When establishing resource recovery systems of wastewater, the implemented technology and materials should be preferentially considered in order to achieve economically feasible and environmentally responsible solutions. The advantages of biochar in cost, nutrient retention and pollutant adsorption efficiency endow its possibility for resource recovery. Thus, understanding the relationship between biochar and resource recovery is essential to develop the applications of biochar in environment remediation and wastewater utilization. However, to this date there is no comprehensive review that establish the relevance between biochar and recycled substance. In this review, we aim to evaluate the roles of biochar in resource recovery from wastewater. Recyclable substances with the presence of biochar mainly include components, water resource and energy. Viable and effective methods for different recovered targets are classified. In particular, through revealing the interrelationship between biochar production methods and recovered substances, we try to provide the guideline for biochar selection. The re-application and value of recovered substances are also summarized comprehensively. Moreover, the current problems, existing limitations, and promising industrial application value of biochar in resource recovery from water are also put forward. This review can create awareness about the possibility of various options for resources recovery from water with biochar and contribute to further development and demonstration in wastewater treatment. [ABSTRACT FROM AUTHOR]

• FeOOH QDs/CQDs/g-C 3 N 4 0D/2D heterojunction has been first prepared. • 0D/2D heterojunction can realize H 2 O 2 generation and in-situ decomposition. • The composite has excellent charge carrier transfer and separation efficiency. • The introduction of CQDs can improve the photoconversion efficiency. • The generated Fe2+ in FeOOH QDs can promote H 2 O 2 in-situ decomposition. Hydrogen peroxide (H 2 O 2) was generally considered as an ideal energy carrier and environment-friendly oxidant to process environmental modification. Here, FeOOH QDs and CQDs was interspersed on g-C 3 N 4 ultrathin nanosheet to promote H 2 O 2 generation and in-situ decomposition. FeOOH QDs/CQDs/g-C 3 N 4 composite (FCCN) exhibited excellent photoactivity for degrading oxytetracycline (OTC) under visible light illumination. The accelerated photoactivity is ascribed to the following merits: 1) the exciton dissociation interface and carrier transfer channel are fabricated to facilitate photoexcited electron transfer; 2) the photoexcited electron can be rapidly utilized by molecular oxygen to generate H 2 O 2 , resulting in facilitated molecular oxygen activation; 3) Fe3+ in FeOOH QDs is reduced to Fe2+ by photoexcited electron, and then reacts with generated H 2 O 2 to produce OH, thereby promoting photodegradation efficiency. The H 2 O 2 generation yield of FCCN-2 composite was 224.24 µmol h−1 g−1, which was higher than that of pure g-C 3 N 4. 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation and O 2 − quantitative determination displayed outstanding molecular oxygen activation capacity of hybrid composite. Moreover, 0D/2D heterojunction photocatalyst displayed weakened charge carrier recombination efficiency (0.0015 s−1) and expedited surface carrier transfer efficiency (41.01%) compared to g-C 3 N 4 and CQDs/g-C 3 N 4 photocatalyst. Finally, the photodegradation mechanism were rationally evaluated based on the experiment results. [ABSTRACT FROM AUTHOR]

• The 2D/2D Bi 2 MoO 6 /Ti 3 C 2 MXene interfacial Schottky heterojunction was first prepared. • 2D/2D Schottky heterojunction accelerated charge carrier separation and transfer. • The formed built-in electric field facilitated hot electron to inject into active sites. • 2D/2D Schottky heterojunction showed superior molecular oxygen activation. • This study paved the new way to realize high molecular oxygen activation efficiency. Visible-light-driven molecular oxygen activation (MOA) is deemed as the potential route to enhance oxidation capacity of molecular oxygen, while activation efficiency is significantly impeded thanks to the deficient charge carrier separation and transfer. In this work, an atomic scale 2D/2D Schottky heterojunction is prepared using titanium carbide as 2D platform for in situ growth of 2D ultrathin bismuth molybdate nanosheet through anaerobically hydrothermal conditions. This 2D/2D Schottky heterojunction displays high performance for MOA, which is 5.56-fold higher than pristine one. The excellent activation efficiency is originated from ultrahigh charge carrier transfer channel, in which the surface charge transfer efficiency is enhanced (30.73 % vs 18.45 %) and the surface recombination constant is decreased (0.0019 s−1 vs 0.0031 s−1) compared to pristine one. The mechanism of photocatalytic MOA is unearthed based on experiment results and various characterizations. This study shows the great potential of atomic scale 2D/2D Schottky heterojunction in photocatalytic MOA. [ABSTRACT FROM AUTHOR]