In situ visualizing reveals potential drive of lattice expansion on defective support toward efficient removal of nitrogen oxides.

As a sustainable and promising approach of removing of nitrogen oxides (NOx), catalytic reduction of NOx with H2 is highly desirable with a precise understanding to the structure-activity relationship of supported catalysts. In particular, the dynamic evolution of support at microscopic scale may play a critical role in heterogeneous catalysis, however, identifying the in situ structural change of support under working condition with atomic precision and revealing its role in catalysis is still a grand challenge. Herein, we visually capture the surface lattice expansion of WO3-x support in Pt-WO3-x catalyst induced by NO in the exemplified reduction of NO with H2 using in situ transmission electron microscopy and first reveal its important role in enhancing catalysis. We find that NO can adsorb on the oxygen vacancy sites of WO3-x and favorably induce the reversible stretching of W-O-W bonds during the reaction, which can reduce the adsorption energy of NO on Pt4 centers and the energy barrier of the rate-determining step. The comprehensive studies reveal that lattice expansion of WO3-x support can tune the catalytic performance of Pt-WO3-x catalyst, leading to 20% catalytic activity enhancement for the exemplified reduction of NO with H2. This work reveals that the lattice expansion of defective support can tune and optimize the catalytic performance at the atomic scale.

Superexchange-induced Pt-O-Ti3+ site on single photocatalyst for efficient H2 production with organics degradation in wastewater.

Efficient photocatalytic H2 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 BaTiO3 single catalyst with oxygen vacancies (BTPOv) that features Pt-O-Ti3+ short charge separation site, which enables excellent H2 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 BaTiO3 (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 Ti3+ 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 Ti3+ defects for oxidation of moxifloxacin. Impressively, the BTPOv shows an exceptional atomic economy and potential for practical applications, a best H2 production TOF (370.4 h-1) among the recent reported dual-functional photocatalysts and exhibiting excellent H2 production activity in multiple types of wastewaters.

Generating dual-active species by triple-atom sites through peroxymonosulfate activation for treating micropollutants in complex water.

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 Bi2O2CO3 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 SO4•- and •OH at the Bi site and an oxidation reaction to generate 1O2 at the Co site. We suggest that the synergistic effect of SO4•-, •OH, and 1O2 enables efficient removal and mineralization of micropollutants without interference from organic and inorganic compounds under the environmental background. As a result, the Co-doped Bi2O2CO3 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.

In situ formation of cocatalytic sites boosts single-atom catalysts for nitrogen oxide reduction.

Nitrogen oxide (NOx) pollution presents a severe threat to the environment and human health. Catalytic reduction of NOx with H2 using single-atom catalysts poses considerable potential in the remediation of air pollution; however, the unfavorable process of H2 dissociation limits its practical application. Herein, we report that the in situ formation of PtTi cocatalytic sites (which are stabilized by Pt-Ti bonds) over Pt1/TiO2 significantly increases NOx conversion by reducing the energy barrier of H2 activation. We demonstrate that two H atoms of H2 molecule are absorbed by adjacent Pt atoms in Pt-O and Pt-Ti, respectively, which can promote the cleave of H-H bonds. Besides, PtTi sites facilitate the adsorption of NO molecules and further lower the activation barrier of the whole de-NOx reaction. Extending the concept to Pt1/Nb2O5 and Pd1/TiO2 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.

Single cobalt atoms anchored on Ti3C2Tx with dual reaction sites for efficient adsorption-degradation of antibiotic resistance genes.

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 CoSA/Ti3C2Tx (single cobalt atoms immobilized on Ti3C2Tx 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-O3 sites). The Ti sites on CoSA/Ti3C2Tx nanosheets bound with PO43- on the phosphate skeletons of ARGs via Ti-O-P coordination interactions, achieving excellent adsorption capacity (10.21 × 1010 copies mg-1) for tetA, and the Co-O3 sites activated PMS into surface-bond hydroxyl radicals (•OHsurface), 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 NO3. 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 strong metal-support interactions induced electrocatalytic three-electron oxygen reduction to hydroxyl radicals for water treatment.

As a promising environmental remediation technology, the electro-Fenton (EF) process is mainly limited by the two rate-limiting steps, which are H2O2 generation and activation. The electrocatalytic three-electron oxygen reduction reaction (3e- ORR) can directly activate oxygen to hydroxyl radicals (•OH), which is expected to break through the rate-limiting steps of the EF process. However, limited success has been achieved in the design of 3e- ORR electrocatalysts. Herein, we propose Cu/CoSe2/C with the strong metal-support interactions to enhance the 3e- ORR process, exhibiting remarkable reactivity and stability for •OH generation. Both experiment and DFT calculation results reveal that CoSe2 is conducive to the generation of H2O2. Meanwhile, the metallic Cu can enhance the adsorption strength of *H2O2 intermediates and thus promotes the one-electron reduction to •OH. The Cu/CoSe2/C catalyst exhibits the electron-transfer number close to 3.0 during the ORR process, and exhibits the outstanding •OH generation performance, achieving a higher apparent rate constant (6.0 times faster) toward ciprofloxacin compared with its analogy without the SMSI effect. Our work represents that the SMSI effect endows Cu/CoSe2/C high activity and selectivity for •OH generation, providing a unique perspective for the design of a high-efficiency 3e- ORR catalyst.

Enhanced localized dipole of Pt-Au single-site catalyst for solar water splitting.

Solar water splitting is regarded as holding great potential for clean fuels production. However, the efficiency of charge separation/transfer of photocatalysts is still too low for industrial application. This paper describes the synthesis of a Pt-Au binary single-site loaded g-C3N4 nanosheet photocatalyst inspired by the concept of the dipole. The existent larger charge imbalance greatly enhanced the localized molecular dipoles over adjacent Pt-Au sites in contrast to the unary counterparts. The superposition of molecular dipoles then further strengthened the internal electric field and thus promoted the charge transportation dynamics. In the modeling photocatalytic hydrogen evolution, the optimal Pt-Au binary site photocatalysts (0.25% loading) showed 4.9- and 2.3-fold enhancement of performance compared with their Pt and Au single-site counterparts, respectively. In addition, the reaction barrier over the Pt-Au binary sites was lowered, promoting the hydrogen evolution process. This work offers a valuable strategy for improving photocatalytic charge transportation dynamics by constructing polynary single sites.

Constructing Nano-Heterostructure with Dual-Site to Boost H2 O2 Activation and Regulate the Transformation of Free Radicals.

A major issue with Fenton-like reaction is the excessive consumption of H2 O2 caused by the sluggish regeneration rate of low-valent metal, and how to improve the activation efficiency of H2 O2 has become a key in current research. Herein, a nano-heterostructure catalyst (1.0-MnCu/C) based on nano-interface engineering is constructed by supporting Cu and MnO on carbon skeleton, and its kinetic rate for the degradation of tetracycline hydrochloride is 0.0436 min-1 , which is 2.9 times higher than that of Cu/C system (0.0151 min-1 ). The enhancement of removal rate results from the introduced Mn species can aggregate and transfer electrons to Cu sites through the electron bridge Mn-N/O-Cu, thus preventing Cu2+ from oxidizing H2 O2 to form O2 •- , and facilitating the reduction of Cu2+ and generating more reactive oxygen species (1 O2 and ·OH) with stronger oxidation ability, resulting in H2 O2 utilization efficiency is 1.9 times as much as that of Cu/C. Additionally, the good and stable practical application capacity in different bodies demonstrates that it has great potential for practical environmental remediation.

Spin Polarization: A New Frontier in Efficient Photocatalysis for Environmental Purification and Energy Conversion.

As a promising strategy to improve photocatalytic efficiency, spin polarization has attracted enormous attention in recent years, which could be involved in various steps of photoreaction. The Pauli repulsion principle and the spin selection rule dictate that the behavior of two electrons in a spatial eigenstate is based on their spin states, and this fact opens up a new avenue for manipulating photocatalytic efficiency. In this review, recent advances in modulating the photocatalytic activity with spin polarization are systematically summarized. Fundamental insights into the influence of spin-polarization effects on photon absorption, carrier separation, and migration, and the behaviors of reaction-related substances from the photon uptake to reactant desorption are highlighted and discussed in detail, and various photocatalytic applications for environmental purification and energy conversion are presented. This review is expected to deliver a timely overview of the recent developments in spin-polarization-modulated photocatalysis for environmental purification and energy conversion in terms of their practical applications.

Deep Oxidation of Chlorinated VOCs by Efficient Catalytic Peroxide Activation over Nanoconfined Co@NCNT Catalysts.

The catalytic removal of chlorinated VOCs (CVOCs) in gas-solid reactions usually suffers from chlorine-containing byproduct formation and catalyst deactivation. AOP wet scrubber has recently attracted ever-increasing interest in VOC treatment due to its advantages of high efficiency and no gaseous byproduct emission. Herein, the low-valence Co nanoparticles (NPs) confined in a N-doped carbon nanotube (Co@NCNT) were studied to activate peroxymonosulfate (PMS) for efficient CVOC removal in a wet scrubber. Co@NCNT exhibited unprecedented catalytic activity, recyclability, and low Co ion leakage (0.19 mg L-1) for chlorobenzene degradation in a very wide pH range (3-11). The chlorobenzene removal efficiency was kept stable above 90% over Co@NCNT, much higher than that of nonconfined Co@NCNS (45%). The low-valence Co NPs achieved a continuous electron redox cycling (Co0/Co2+ → Co3+ → Co0/Co2+) and greatly promoted the O-O bond dissociation of PMS with the least energy (0.83 eV) inside the channel of Co@NCNT to form abundant HO• and SO4•-. Thus, the deep oxidation of chlorobenzene was achieved without any biphenyl byproducts from the coupling reaction. This study provided a new avenue for designing novel nanoconfined catalysts with outstanding activity, paving the way for the deep oxidation of CVOC waste gas via AOP wet scrubber.

Iron hydroxyphosphate electro-Fenton catalyst for efficient removal of sulfamethoxazole and resource recycling into slow-release fertiliser ammonium ferrous phosphate.

Although the electro-Fenton (EF) process is effective for wastewater treatment, recycling spent catalysts remain a major challenge. Therefore, we introduce a reuse strategy for spent catalysts where an iron hydroxyphosphate [Fe5(PO4)4(OH)3·2H2O] catalyst is utilized. Fe5(PO4)4(OH)3·2H2O obtained •OH and •O2- by activating in-situ produced H2O2, and the degradation rate of sulfamethoxazole reached 94.5% after 120 min and showed excellent stability (maintained above 90%) for 10 cycles. Finally, the used catalyst was converted into slow-release ammonium ferrous phosphate (NH4FePO4·H2O) fertiliser at a conversion rate of 85.6%. NH4FePO4·H2O significantly promoted plant and seed growth within 6 days, highlighting the contribution of the resource recycling of the spent catalyst. This study serves as a valuable reference for the efficient utilization of spent catalysts. This study successfully applied EF catalysts and explored the recycling of spent catalysts.

Tailoring of electronic and surface structures boosts exciton-triggering photocatalysis for singlet oxygen generation.

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 Bi3O4Br, thereby enhancing the propensity to generate 1O2 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 O2 causes the changes in the magnetic moment (i.e., spin state) of O2 through electron-mediated triplet energy transfer, resulting a spontaneous spin-flip process and highly specific 1O2 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.

Selective Photoreforming of Waste Plastics into Diesel Olefins via Single Reactive Oxygen Species.

The accumulation of plastic waste poses a pressing environmental challenge. Catalytic conversion stands out as an ideal approach for plastics upcycling, particularly through solar-driven plastics photoreforming. However, due to the common effects of multiple reactive oxygen species (ROS), selectively generating high-value chemicals becomes challenging. In this study, we developed a universal strategy to achieve >85 % selective production of diesel olefins (C15-C28) from polyolefin waste plastics via single ROS. Using tetrakis (4-carboxyphenyl) porphyrin supramolecular (TCPP) with different central metals as an example to regulate single ROS generation, results show Ni-TCPP facilitates triplet exciton production, yielding 1O2, while Zn-TCPP generates ⋅O2 - due to its strong built-in electric field (IEF). 1O2 directly dechlorinates polyvinyl chloride (PVC) due to the electro-negativity of chlorine atoms and the low dissociation energy of C-Cl bonds, while ⋅O2 - promotes direct dehydrogenation of polyethylene (PE) due to the electro-positivity of hydrogen atoms and the high dissociation energy of C-H bonds. This method is universally applicable to various single ROS systems. Installation experiments further affirm the application potential, achieving the highest diesel olefin production of 76.1 µmol h-1. Such a universally adaptive approach holds promise for addressing the global plastic pollution problem.

Electronic Metal-Support Interactions Boost *OOH Intermediate Generation in Cu/In2Se3 for Electrochemical H2O2 Production.

Two-electron oxygen reduction reaction (2e- ORR) is a promising method for the synthesis of hydrogen peroxide (H2O2). However, high energy barriers for the generation of key *OOH intermediates hinder the process of 2e- ORR. Herein, we prepared a copper-supported indium selenide catalyst (Cu/In2Se3) to enhance the selectivity and yield of 2e- ORR by employing an electronic metal-support interactions (EMSIs) strategy. EMSIs-induced charge rearrangement between metallic Cu and In2Se3 is conducive to *OOH intermediate generation, promoting H2O2 production. Theoretical investigations reveal that the inclusion of Cu significantly lowers the energy barrier of the 2e- ORR intermediate and impedes the 4e- ORR pathway, thus favoring the formation of H2O2. The concentration of H2O2 produced by Cu/In2Se3 is ~2 times than In2Se3, and Cu/In2Se3 shows promising applications in antibiotic degradation. This research presents a valuable approach for the future utilization of EMSIs in 2e- ORR.

Enhancement of Pt-O Synergistic Sites through Titanium Vacancies for Low-Temperature Nitrogen Oxide Reduction.

Improving the reaction rate of each step is significant for accelerating the multistep reaction of NO reduction by H2. However, simultaneously enhancing the activation of different gaseous reactants using single-atom catalysts remains a challenge to maximize the activity. Herein, we propose a strategy that utilizes titanium-vacancy-regulated electronic properties of single atoms and defective support (Pt1/d-TiO2) to facilitate electron transfer from edge-share O atoms (OTi) to adjacent Pt single atoms. This leads to the formation of low-valence Pt and unsaturated-charge OTi sites, which causes the catalytic reaction to follow a synergistic mechanism. Specifically, experimental and theoretical analyses demonstrate that low-valence Pt sites finely tune the adsorption of H2 molecules, consequently lowering the dissociation energy from 0.15 to as low as 0.01 eV. Moreover, using quasi-in situ spectroscopy, we clearly observe NO molecules being adsorbed on interfacial oxygen sites of a defective support. Then, the bond energy of the N-O bond is weakened through an electron acceptance-donation mechanism between unsaturated-charge OTi sites and NO, thereby facilitating NO activation. The designed single-atom catalysts with synergistic sites exhibit unmatched activity at low temperatures (above 90% NOx conversion at 100 °C), along with higher turnover frequency value (0.74 s-1) and superior stability, making them potentially suitable for industrial applications.

Degradation of bisphenol A by persulfate activation of MoS2 composite iron tailings.

In this paper, molybdenum disulfide was grown on the surface of iron-containing tailings by hydrothermal method, and a series of highly efficient activated persulfate (PMS) iron-based catalysts were successfully prepared. The results show that in the CTM 1-200/PMS system, the additional ratio of tailings and the hydrothermal temperature have important effects on the catalyst. The catalyst prepared under the conditions of CT:MoS2 (molar ratio 1:1) and hydrothermal temperature of 200 °C (CTM 1-200) had the best degradation effect on BPA, and the degradation effect was increased by four times. The reason for the improvement of degradation efficiency is that the introduction of MoS2 accelerates the REDOX cycle between Fe(II)/Fe(III), and the reduction of Fe(III) is mainly related to Mo(IV), while the reduction capacity of S is relatively weak. Molybdenum disulfide/iron tailing composite material provides a way for tailings to solve the problem of water pollution.

Enhanced Interfacial Electron Transfer by Asymmetric Cu-Ov -In Sites on In2 O3 for Efficient Peroxymonosulfate Activation.

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 In2 O3 (Cu-In2 O3 /Ov ) catalysts containing asymmetric Cu-Ov -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-Ov -In sites significantly stretches the O-O bond length. Meanwhile, the Cu-Ov -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 SO4 ⋅- and ⋅OH. The degradation rate constant of tetracycline achieved by Cu-In2 O3 /Ov is 31.8 times faster than In2 O3 /Ov , and it shows the possibility of membrane reactor for practical wastewater treatment.

Regulating Spin Polarization through Cationic Vacancy Defects in Bi4 Ti3 O12 for Enhanced Molecular Oxygen Activation.

Molecular oxygen (O2 ) activation technology is of great significance in environmental purification due to its eco-friendly operation and cost-effective nature. However, the activation of O2 is limited by spin-forbidden transitions, and efficient molecular oxygen activation depends on electronic behavior and surface adsorption. Herein, we prepared cationic defect-rich Bi4 Ti3 O12 (BTO-MV2) catalysts containing Ti vacancies (VTi ) for O2 activation in water purification. The VTi 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 VTi is also formed, serving as a center for adsorbing O2 and extracting electrons, effectively generating ⋅OH, O2 ⋅- and 1 O2 . 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.

Efficient Removal of Antibiotic Resistance Genes through 4f-2p-3d Gradient Orbital Coupling Mediated Fenton-Like Redox Processes.

Peroxymonosulfate (PMS) mediated radical and nonradical active substances can synergistically achieve the efficient elimination of antibiotic resistance genes (ARGs). However, enhancing interface electron cycling and optimizing the coupling of the oxygen-containing intermediates to improve PMS activation kinetics remains a major challenge. Here, Co doped CeVO4 catalyst (Co-CVO) with asymmetric sites was constructed based on Ce 4f-O 2p-Co 3d gradient orbital coupling. The catalyst achieved approximately 2.51×105 copies/mL of extracellular ARGs (eARGs) removal within 15 minutes, exhibited ultrahigh degradation rate (k=1.24 min-1 ). The effective gradient 4f-2p-3d orbital coupling precisely regulates the electron distribution of Ce-O-Co active center microenvironment, while optimizing the electronic structure of Co 3d states (especially the occupancy of eg ), promoting the adsorption of oxygen-containing intermediates. The generated radical and nonradical generated by interfacial electron cycling enhanced by the reduction reaction of PMS at the Ce site and the oxidation reaction at the Co site achieved a significant mineralization rate of ARGs (83.4 %). The efficient removal of ARGs by a continuous flow reactor for 10 hours significantly reduces the ecological risk of ARGs in actual wastewater treatment.

Facilitating Redox Cycles of Copper Species by Pollutants in Peroxymonosulfate Activation.

The redox behavior of metal active sites determines the rate of heterogeneous catalysis in peroxymonosulfate activation. Previous reports focused on the construction of catalysts for accelerating interfacial electron transfer. In this work, a new strategy was proposed for facilitating valence cycles of Cu+/Cu2+ by using pollutants. The 2.5Cu/CeO2/PMS system was capable of achieving the efficient removal of pollutants, including tetracycline, oxytetracycline, and rhodamine B, in a wide pH working range. In the presence of tetracycline, a Cu-N bond was formed between the -NH2 group of tetracycline and the Cu site of the catalyst, showing that the coordination of Cu active sites changed to CuO4N1. The charge of CuO4N1 active sites rearranged, making it easier to obtain electrons and promote the PMS oxidation, thereby accelerating the reduction of Cu2+ to Cu+ and PMS activation. The PMS activation system showed excellent sustainability and selectivity for the removal of organic pollutants. This study provides a novel routine to promote peroxymonosulfate activation by utilizing pollutants to accelerate the redox behavior of metal species.