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The assimilation of antibiotic resistance genes (ARGs) by pathogenic bacteria poses a severe threat to public health. Here, we reported a dual-reaction-site-modified Co SA /Ti 3 C 2 T x (single cobalt atoms immobilized on Ti 3 C 2 T x MXene) for effectively deactivating extracellular ARGs via peroxymonosulfate (PMS) activation. The enhanced removal of ARGs was attributed to the synergistic effect of adsorption (Ti sites) and degradation (Co-O 3 sites). The Ti sites on Co SA /Ti 3 C 2 T x nanosheets bound with PO 4 3- on the phosphate skeletons of ARGs via Ti-O-P coordination interactions, achieving excellent adsorption capacity (10.21 × 10 10 copies mg -1 ) for tetA, and the Co-O 3 sites activated PMS into surface-bond hydroxyl radicals (•OH surface ), which can quickly attack the backbones and bases of the adsorbed ARGs, resulting in the efficient in situ degradation of ARGs into inactive small molecular organics and NO 3 . This dual-reaction-site Fenton-like system exhibited ultrahigh extracellular ARG degradation rate (k > 0.9 min -1 ) and showed the potential for practical wastewater treatment in a membrane filtration process, which provided insights for extracellular ARG removal via catalysts design.

The optimization of the single-atom catalyst (SAC) performance has been the hot spot for years. It is widely acknowledged that the incorporation of adjacent single-atom sites (diatomic catalysts (DACs)) can enable synergistic effects, which can be used in cascade catalysis, dual-function catalysis, and performance regulation of intrinsic active sites. DACs have been widely applied in the CO 2 reduction reaction (CO 2 RR), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), etc. ; however, their application is limited in Fenton or Fenton-like reactions. This perspective summarizes the most advanced achievements in this field, followed by the proposed opportunities in further research, including regulation of the magnetic moment, inter-atomic distance effect, strain engineering, atomic cluster (AC)/nanoparticle (NP) modification, etc . It is demonstrated that this perspective can contribute to the DAC application in Fenton or Fenton-like reactions with innovative design and mechanisms being put forward., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Efficient photocatalytic H 2 production from wastewater instead of pure water is a dual solution to the environmental and energy crisis, but due to the rapid recombination of photoinduced charge in the photocatalyst and inevitable electron depletion caused by organic pollutants, a significant challenge of dual-functional photocatalysis (simultaneous oxidative and reductive reactions) in single catalyst is designing spatial separation path for photogenerated charges at atomic level. Here, we designed a Pt-doped BaTiO 3 single catalyst with oxygen vacancies (BTPO v ) that features Pt-O-Ti 3+ short charge separation site, which enables excellent H 2 production performance (1519 μmol·g -1 ·h -1 ) while oxidizing moxifloxacin ( k = 0.048 min -1 ), almost 43 and 98 times than that of pristine BaTiO 3 (35 μmol·g -1 ·h -1 and k = 0.00049 min -1 ). The efficient charge separation path is demonstrated that the oxygen vacancies extract photoinduced charge from photocatalyst to catalytic surface, and the adjacent Ti 3+ defects allow rapid migration of electrons to Pt atoms through the superexchange effect for H * adsorption and reduction, while the holes will be confined in Ti 3+ defects for oxidation of moxifloxacin. Impressively, the BTPO v shows an exceptional atomic economy and potential for practical applications, a best H 2 production TOF (370.4 h -1 ) among the recent reported dual-functional photocatalysts and exhibiting excellent H 2 production activity in multiple types of wastewaters.

Molecular oxygen (O 2 ) activation technology is of great significance in environmental purification due to its eco-friendly operation and cost-effective nature. However, the activation of O 2 is limited by spin-forbidden transitions, and efficient molecular oxygen activation depends on electronic behavior and surface adsorption. Herein, we prepared cationic defect-rich Bi 4 Ti 3 O 12 (BTO-MV2) catalysts containing Ti vacancies (V Ti ) for O 2 activation in water purification. The V Ti on BTO nanosheets can induce electron spin polarization, increasing the number of spin-down photogenerated electrons and reducing the recombination of electron-hole pairs. An active surface V Ti is also formed, serving as a center for adsorbing O 2 and extracting electrons, effectively generating ⋅OH, O 2 ⋅ - and 1 O 2 . The degradation rate constant of tetracycline achieved by BTO-MV2 is 3.3 times faster than BTO, indicating a satisfactory prospect for practical application. This work provides an efficient pathway to activate molecular oxygen by constructing new active sites through cationic vacancy modification technology., (© 2023 Wiley-VCH GmbH.)

The peroxymonosulfate (PMS)-triggered radical and nonradical active species can synergistically guarantee selectively removing micropollutants in complex wastewater; however, realizing this on heterogeneous metal-based catalysts with single active sites remains challenging due to insufficient electron cycle. Herein, we design asymmetric Co-O-Bi triple-atom sites in Co-doped Bi 2 O 2 CO 3 to facilitate PMS oxidation and reduction simultaneously by enhancing the electron transfer between the active sites. We propose that the asymmetric Co-O-Bi sites result in an electron density increase in the Bi sites and decrease in the Co sites, thereby PMS undergoes a reduction reaction to generate SO 4 •- and •OH at the Bi site and an oxidation reaction to generate 1 O 2 at the Co site. We suggest that the synergistic effect of SO 4 •- , •OH, and 1 O 2 enables efficient removal and mineralization of micropollutants without interference from organic and inorganic compounds under the environmental background. As a result, the Co-doped Bi 2 O 2 CO 3 achieves almost 99.3% sulfamethoxazole degradation in 3 min with a k-value as high as 82.95 min -1 M -1 , which is superior to the existing catalysts reported so far. This work provides a structural regulation of the active sites approach to control the catalytic function, which will guide the rational design of Fenton-like catalysts.

Enhancing the peroxymonosulfate (PMS) activation efficiency to generate more radicals is vital to promote the Fenton-like reaction activity, however, how to promote the PMS adsorption and accelerate the interfacial electron transfer to boost its activation kinetics remains a great challenge. Herein, we prepared Cu-doped defect-rich In 2 O 3 (Cu-In 2 O 3 /O v ) catalysts containing asymmetric Cu-O v -In sites for PMS activation in water purification. The intrinsic catalytic activity is that the side-on adsorption configuration of the O-O bond (Cu-O-O-In) at the Cu-O v -In sites significantly stretches the O-O bond length. Meanwhile, the Cu-O v -In sites increase the electron density near the Fermi energy level, promoting more and faster electron transfer to the O-O bond for generating more SO 4 ⋅ - and ⋅OH. The degradation rate constant of tetracycline achieved by Cu-In 2 O 3 /O v is 31.8 times faster than In 2 O 3 /O v , and it shows the possibility of membrane reactor for practical wastewater treatment., (© 2023 Wiley-VCH GmbH.)

Nitrogen oxide (NO x ) pollution presents a severe threat to the environment and human health. Catalytic reduction of NO x with H 2 using single-atom catalysts poses considerable potential in the remediation of air pollution; however, the unfavorable process of H 2 dissociation limits its practical application. Herein, we report that the in situ formation of Pt Ti cocatalytic sites (which are stabilized by Pt-Ti bonds) over Pt 1 /TiO 2 significantly increases NO x conversion by reducing the energy barrier of H 2 activation. We demonstrate that two H atoms of H 2 molecule are absorbed by adjacent Pt atoms in Pt-O and Pt-Ti, respectively, which can promote the cleave of H-H bonds. Besides, Pt Ti sites facilitate the adsorption of NO molecules and further lower the activation barrier of the whole de-NO x reaction. Extending the concept to Pt 1 /Nb 2 O 5 and Pd 1 /TiO 2 systems also sees enhanced catalytic activities, demonstrating that engineering the cocatalytic sites can be a general strategy for the design of high-efficiency catalysts that can benefit environmental sustainability.

Due to environmentally friendly operation and on-site productivity, electrocatalytic singlet oxygen ( 1 O 2 ) production via O 2 gas is of immense interest in environment purification. However, the side-on configuration of O 2 on the catalysts surface will lead to the formation of H 2 O, which seriously limits the selectivity and activity of 1 O 2 production. Herein, we show a robust N-doped CuO (N-CuO) with Pauling-type (end-on) adsorption of O 2 at the N-Cu-O 3 sites for the selective generation of 1 O 2 under direct-current electric field. We propose that Pauling-type configuration of O 2 not only lowers the overall activation energy barrier, but also alters the reaction pathway to form 1 O 2 instead of H 2 O, which is the key feature determining selectivity for the dissociation of Cu-O bonds rather than the O-O bonds. The proposed N dopant strategy is applicable to a series of transition metal oxides, providing a universal electrocatalysts design scheme for existing high-performance electrocatalytic 1 O 2 production., (© 2022. The Author(s).)

Arising from reduced dielectric screening, excitonic effects should be taken into account in ultrathin two-dimensional photocatalysts, and a significant challenge is achieving nontrivial excitonic regulation. However, the effect of structural modification on the regulation of the excitonic aspect is at a comparatively early stage. Herein, we report unusual effects of surface substitutional doping with Pt on electronic and surface characteristics of atomically thin layers of Bi 3 O 4 Br, thereby enhancing the propensity to generate 1 O 2 Electronically, the introduced Pt impurity states with a lower energy level can trap photoinduced singlet excitons, thus reducing the singlet-triplet energy gap by ∼48% and effectively facilitating the intersystem crossing process for efficient triplet excitons yield. Superficially, the chemisorption state of O 2 causes the changes in the magnetic moment (i.e., spin state) of O 2 through electron-mediated triplet energy transfer, resulting a spontaneous spin-flip process and highly specific 1 O 2 generation. These traits exemplify the opportunities that the surface engineering provides a unique strategy for excitonic regulation and will stimulate more research on exciton-triggering photocatalysis for solar energy conversion., Competing Interests: The authors declare no competing interest.

The sluggish regeneration rate of Fe II and low operating pH still restrict the wider application of classical Fenton process (Fe II /H 2 O 2 ) for practical water treatment. To overcome these challenges, we exploit the Mn-CNH co-catalyst to construct a solid-liquid interfacial Fenton reaction and accelerate the Fe III /Fe II redox cycle at the interface for sustainably generating • OH from H 2 O 2 activation. The Mn-CNH co-catalyst exhibits an excellent regeneration rate of Fe II (∼65%) and a high tetracycline removal rate ( K obs ) of 0.0541 min -1 , which is 19.0 times higher than that of the Fe II /H 2 O 2 system (0.0027 min -1 ) at a near-neutral pH (pH ≈ 5.8), and it also attains 100% degradation of sulfamethoxazole, rhodamine B, and methyl orange. The cyclic mechanism of Fe III /Fe II is further elucidated in an atomic scale by combining characterizations and density functional theory calculations, including Fe aq III specific adsorption and the electron-transfer process. Mn active sites can accumulate electrons from the matrix and adsorb Fe aq III to form Mn-Fe bonds at the solid-liquid interface, which accelerate electron transfer from Mn-CNH to Fe aq III and promote the regeneration of Fe II at a wide pH range with a lower energy barrier. The regeneration rate of Fe II in the Mn-CNH/Fe II /H 2 O 2 system outperforms the benchmark Fenton system and other typical metal nanomaterials, which has great potential to be widely applied in actual environment remediation.

Single-atom CoN 4 active sites have demonstrated excellent efficiency in peroxymonosulfate activation. However, the identification of CoN 4 active sites and the detailed singlet oxygen generation mechanism in peroxymonosulfate activation remains ambiguous. We demonstrate a strategy to regulate the generation of reactive oxygen species by atomically dispersed cobalt anchored on nitrogen-doped carbon. As indicated by experiment and DFT calculations, CoN 2+2 was the active site and singlet oxygen was the predominant reactive oxygen species with a proportion of 98.89 %. Spontaneous dissociation of adsorbed peroxymonosulfate on the CoN 2+2 active sites was energetically unfavorable because of the weakly positive Co atoms and CoN 2+2 coordination, which directed PMS oxidation by a non-radical pathway and with simultaneous singlet oxygen generation. The generated singlet oxygen degraded several organic pollutants with high efficiency across a broad pH range., (© 2020 Wiley-VCH GmbH.)

Defects in nanomaterials often lead to properties that are absent in their pristine counterparts. To date, most studies have focused on the effect of single defects, while ignoring the synergy of multiple defects. In this study, a model of photocatalytic O 2 activation was selected to unravel the role of dual defects by decorating bismuth oxide with surface O vacancies and bulk O substitution simultaneously. The introduction of dual defects led to a spatial and electronic synergistic process: i) O substitution induced a local electric field in the bulk of BiO 2-x , which promoted bulk separation of electrons and holes immediately after their generation; ii) O vacancies efficiently lowered the conduction band, served as the capture center for electrons, and thus facilitated the adsorption and activation of O 2 . This effect was greatly promoted by the coexistence of bulk O substitution, and DFT calculations showed that only O substitution near an O vacancy could have this effect., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Polyacrylamide (PAM) in environmental water has become a major problem in water pollution management due to its high molecular mass, corrosion resistance, high viscosity, and nonabsorption by soil. The composite of Fe-doped Ce 0.75 Zr 0.25 O 2 solid solution (Fe-Ce 0.75 Zr 0.25 O 2 ) loaded on carbon felt (CF) was fabricated by a hydrothermal synthesis method, which was used as the cathode in a heterogeneous electro-Fenton system for the degradation of PAM. It showed that the degradation efficiency of PAM by the Fe-Ce 0.75 Zr 0.25 O 2 /CF cathode was 86% after 120 min and the molecular mass of PAM decreased by more than 90% after 300 min. Total organic carbon removal reached 78.86% in the presence of Fe-Ce 0.75 Zr 0.25 O 2 /CF, while the value was only 38.01% in the absence of Fe-Ce 0.75 Zr 0.25 O 2 . Further studies showed that the breaking of the chain begins with the amide bond, and then, the carbon chain was cracked into a short alkyl chain. As degradation progressed, both the complex viscosity and elasticity modulus of PAM solutions decreased nearly 50% at 300 min. It indicated that • OH were the most significant active species for the degradation of PAM. This novel Fe-Ce 0.75 Zr 0.25 O 2 /CF composite is an efficient and promising electrode for the removal of PAM in wastewater.

The unexpected phenomenon and mechanism of the alkali metal involved NH 3 selective catalysis are reported. Incorporation of K + (4.22 wt %) in the tunnels of α-MnO 2 greatly improved its activity at low temperature (50-200 °C, 100 % conversion of NO x vs. 50.6 % conversion over pristine α-MnO 2 at 150 °C). Experiment and theory demonstrated the atomic role of incorporated K + in α-MnO 2 . Results showed that K + in the tunnels could form a stable coordination with eight nearby O sp 3 atoms. The columbic interaction between the trapped K + and O atoms can rearrange the charge population of nearby Mn and O atoms, thus making the topmost five-coordinated unsaturated Mn cations (Mn 5c , the Lewis acid sites) more positive. Therefore, the more positively charged Mn 5c can better chemically adsorb and activate the NH 3 molecules compared with its pristine counterpart, which is crucial for subsequent reactions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Visible-light-driven photocatalytic disinfection is highly desired for water treatment due to its advantages such as wide applicability and being free of disinfection byproducts. In this study, AgBr/g-C 3 N 4 hybrid nanocomposites were evaluated as photocatalysts under visible light irradiation for water disinfection using Escherichia coli as a model pathogen. The physicochemical and photo-electrochemical properties of the photocatalyst were systematically characterized using advanced techniques including scanning electron microscopy (SEM), transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra and electron spin resonance (ESR) spectroscopy. The inactivation mechanism of E. coli was systematically investigated by monitoring the morphology change of the bacteria and analyzing the role of reactive species. The optimized AgBr/g-C 3 N 4 hybrid photocatalyst exhibited remarkably enhanced visible-light-driven photocatalytic disinfection performance towards E. coli over that of pure g-C 3 N 4 and AgBr under visible light, which could completely inactivate 10 7 cfu mL -1 E. coli in 90 min. Quenching studies indicated that h + is the main reactive species responsible for inactivating E. coli . The mechanism study revealed a Z-scheme charge transfer mechanism between AgBr and g-C 3 N 4 . The g-C 3 N 4 could effectively trap the photogenerated conduction band electrons of AgBr via a Z-scheme type of route, thus significantly promoting the electron-hole separation. The trapping of electrons by g-C 3 N 4 could facilitate h + accumulation, which accounts for the better disinfection performance of AgBr/g-C 3 N 4 compared to AgBr and g-C 3 N 4 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In spite of intensive research investigating the prevalent Pt/Al 2 O 3 catalysts, achieving macroscopic morphology beyond the powder form limitations remains highly challenging. Meanwhile, current impregnation-based preparation approaches show the drawbacks of tedious procedures and inefficient use of noble metals. Therefore, it is important to search for new methods for the fabrication of Pt/Al 2 O 3 catalysts with a novel morphology. In this study, a novel Pt/Al 2 O 3 nanofibrous membrane catalyst is fabricated via a facile one-pot electrospinning process. The embedding of Pt nanoparticles is performed simultaneously with the formation of Al 2 O 3 nanofibers. The Pt/Al 2 O 3 membranes show remarkable mechanical properties with tensile stresses as high as 44.14 MPa. Notably, the Pt/Al 2 O 3 membranes exhibit multifunctionality with excellent performance characteristics. The catalytic experiments indicate that 100% of bisphenol A is removed within 60 min, and 100% of CO is completely converted to CO 2 at 242 °C when Pt/Al 2 O 3 membranes are used as catalysts. The membranes also exhibit excellent filtration performance, clearly decreasing the turbidity of water, and meet the high efficiency of particulate air filter standards. The excellent flexibility, satisfying mechanical property, and multifunctionality extend the range of potential application of the Pt/Al 2 O 3 membranes. Moreover, the facile synthesis suggests new possibilities for the fabrication of many membrane-form Al 2 O 3 -supported catalysts.

Long TiO2 hollow fibers with mesoporous walls have been fabricated with the sol-gel combined two-capillary spinneret electrospinning technique using a triblock copolymer (Pluronic, P123, (H(C2H5O)20(C3H7O)70 (C2H5O)20OH) as a pore-directing agent. The as-prepared hollow fibers were as long as 30 cm with an outer diameter of 0.1-4 microm and wall thickness of 60-500 nm. The diameters and wall thicknesses of the hollow fibers could be tuned by adjusting the electrospinning parameters. The fiber walls were composed of mesopores 6.7 nm in diameter as calculated from the N2 adsorption/desorption isotherm. The high-resolution TEM (HR-TEM) images exhibited that the mesopores were hexagonally aligned with a low order because of the curving of the pores. When comparing with other nanostructured TiO2 materials such as commercial TiO2 nanoparticles (P25, Degussa) and mesoporous TiO2 powders, the hollow fibers exhibited higher photocatalytic activities toward degradation of methylene blue and gaseous formaldehyde.