Fe/Fe 3 C Boosts H 2 O 2 Utilization for Methane Conversion Overwhelming O 2 Generation

Oxygen vacancy-dependent synergistic disinfection of antibiotic-resistant bacteria by BiOBr nanoflower induced H2O2 activation

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

Photocatalytic CH4-to-Ethanol Conversion on Asymmetric Multishelled Interfaces

The selective oxidation of methane (CH4) features attractive potentials in both mitigating global warming and producing value-added chemicals. However, due to the short-life and unpaired concentrations of reactive intermediates (such as ·OH, ·CH3, and CO), the selective formation of multicarbon products like ethanol has remained challenging. In this work, we developed a hollow multishelled CeO2@PdO@FeOx nanosphere catalyst with two asymmetric and closely connected interfaces, featuring efficient in-tandem photo-oxidation of CH4 into ethanol with O2 as the oxidant. The outer FeOx surface promotes the photoreduction of the oxazole atoms in O2. In the meantime, the two asymmetric PdO/FeOx and CeO2/PdO catalytic interfaces enable selective photoactivation of CH4 to ·CH3 and then to CO, respectively, and the hollow multishelled structure further facilitates the directional transport and coupling of the as-generated ·CH3 and CO to produce ethanol. Under 100 mW·cm-2 light intensity and ambient conditions, the hollow multishelled CeO2@PdO@FeOx nanosphere photocatalyst exhibited a peak CH4-to-ethanol yield of 728 μmol·g-1·h-1 without photosensitizers or sacrificial agents, almost three times higher than the previous best reports on photocatalytic CH4 oxidation to ethanol, suggesting the attractive potential of the asymmetric multishelled catalytic interfaces.

Advances of Synergistic Electrocatalysis Between Single Atoms and Nanoparticles/Clusters

Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts. Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance, simultaneously provide a radical analysis of the interrelationship between structure and activity. In this review, the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized. Firstly, the synthetic strategies, characterization, dynamics and types of single atoms coupled with clusters/nanoparticles are introduced, and then the key factors controlling the structure of the composite catalysts are discussed. Next, several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated. Eventually, the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.

Iron Active Center Coordination Reconstruction in Iron Carbide Modified on Porous Carbon for Superior Overall Water Splitting

In this work, a novel liquid nitrogen quenching strategy is engineered to fulfill iron active center coordination reconstruction within iron carbide (Fe3C) modified on biomass-derived nitrogen-doped porous carbon (NC) for initiating rapid hydrogen and oxygen evolution, where the chrysanthemum tea (elm seeds, corn leaves, and shaddock peel, etc.) is treated as biomass carbon source within Fe3C and NC. Moreover, the original thermodynamic stability is changed through the corresponding force generated by liquid nitrogen quenching and the phase transformation is induced with rich carbon vacancies with the increasing instantaneous temperature drop amplitude. Noteworthy, the optimizing intermediate absorption/desorption is achieved by new phases, Fe coordination, and carbon vacancies. The Fe3C/NC-550 (550 refers to quenching temperature) demonstrates outstanding overpotential for hydrogen evolution reaction (26.3 mV at -10 mA cm-2) and oxygen evolution reaction (281.4 mV at 10 mA cm-2), favorable overall water splitting activity (1.57 V at 10 mA cm-2). Density functional theory (DFT) calculations further confirm that liquid nitrogen quenching treatment can enhance the intrinsic electrocatalytic activity efficiently by optimizing the adsorption free energy of reaction intermediates. Overall, the above results authenticate that liquid nitrogen quenching strategy open up new possibilities for obtaining highly active electrocatalysts for the new generation of green energy conversion systems.

Steering Photooxidation of Methane to Formic Acid over A Priori Screened Supported Catalysts

Efficient methane photooxidation to formic acid (HCOOH) has emerged as a sustainable approach to simultaneously generate value-added chemicals and harness renewable energy. However, the persistent challenge lies in achieving a high yield and selectivity for HCOOH formation, primarily due to the complexities associated with modulating intermediate conversion and desorption after methane activation. In this study, we employ first-principles calculations as a comprehensive guiding tool and discover that by precisely controlling the O2 activation process on noble metal cocatalysts and the adsorption strength of carbon-containing intermediates on metal oxide supports, one can finely tune the selectivity of methane photooxidation products. Specifically, a bifunctional catalyst comprising Pd nanoparticles and monoclinic WO3 (Pd/WO3) would possess optimal O2 activation kinetics and an intermediate oxidation/desorption barrier, thereby promoting HCOOH formation. As evidenced by experiments, the Pd/WO3 catalyst achieves an exceptional HCOOH yield of 4.67 mmol gcat-1 h-1 with a high selectivity of 62% under full-spectrum light irradiation at room temperature using molecular O2. Notably, these results significantly outperform the state-of-the-art photocatalytic systems operated under identical condition.

Enhancing photocatalytic hydrogen production of carbon nitride: Dominant advantage of crystallinity over mass transfer

Mass transfer enhancement and crystallinity engineering are two prevailing technologies for photocatalyst modification. However, their relative effectiveness in enhancing photocatalytic activity remains unclear due to the lack of rational probing catalysts. In this study, we synthesized two distinct carbon nitride (C3N4) catalysts: one with a high specific surface area (CN-HA) and the other with improved crystallinity (CN-HC). These catalysts served as probes to compare their respective impacts on photocatalytic activities. Comprehensive characterization techniques and density functional theory (DFT) calculation results unveiled that crystallinity played a dominant role in light absorption and charge dynamics, while surface area primarily influenced mass transfer in photocatalysis. Importantly, our findings revealed that crystallinity engineering of photocatalyst achieved a greater impact on photocatalytic hydrogen evolution than that from mass transfer enhancement. Consequently, CN-HC demonstrated a remarkable improvement in photocatalytic performance for hydrogen evolution (6465.4 μmol h-1 g-1), surpassing both C3N4 and CN-HA by 19.4- and 2.4-fold, respectively, accompanied by a high apparent quantum yield of 23.8 % at 420 nm. This study not only unveils the dominant factor influencing the activity of photocatalysts but also provides a modified approach for robust solar fuel production, shedding light on the path toward efficient and sustainable energy conversion.

Cl2 ⋅- Mediates Direct and Selective Conversion of Inert C(sp3 )-H Bonds into Aldehydes/Ketones

Developing new reactive pathway to activate inert C(sp3 )-H bonds for valuable oxygenated products remains a challenge. We prepared a series of triazine conjugated organic polymers to photoactivate C-H into aldehyde/ketone via O2 →H2 O2 →⋅OH→Cl⋅→Cl2 ⋅- . Experiment results showed Cl2 ⋅- could successively activate C(sp3 )-H more effectively than Cl⋅ to generate unstable dichlorinated intermediates, increasing the kinetic rate ratio of dichlorination to monochlorination by a factor of 2,000 and thus breaking traditional dichlorination kinetic constraints. These active intermediates were hydrolyzed into aldehydes or ketones easily, when compared with typical stable dichlorinated complexes, avoiding chlorinated by-product generation. Moreover, an integrated two-phase system in an acid solution strengthened the Cl2 ⋅- mediated process and inhibited product overoxidation, where the conversion rate of toluene reached 16.94 mmol/g/h and the selectivity of benzaldehyde was 99.5 %. This work presents a facile and efficient approach for selective conversion of inert C(sp3 )-H bonds using Cl2 ⋅- .

Selective hydroxyl generation for efficient pollutant degradation by electronic structure modulation at Fe sites

Hydrogen peroxide (H2O2) is an important green oxidant in the field of sewage treatment, and how to improve its activation efficiency and generate free radicals with stronger oxidation performance is a key issue in current research. Herein, we synthesized a Cu-doped α-Fe2O3 catalyst (7% Cu-Fe2O3) for activation of H2O2 under visible light for degradation of organic pollutants. The introduction of a Cu dopant changed the d-band center of Fe closer to the Fermi level, which enhanced the adsorption and activation of the Fe site for H2O2, and the cleavage pathway of H2O2 changed from heterolytic cleavage to homolytic cleavage, thereby improving the selectivity of •OH generation. In addition, Cu doping also promoted the light absorption ability of α-Fe2O3 and the separation of hole-electron pairs, which enhanced its photocatalytic activities. Benefiting from the high selectivity of •OH, 7% Cu-Fe2O3 exhibited efficient degradation activities against ciprofloxacin, the degradation rate was 3.6 times as much as that of α-Fe2O3, and it had good degradation efficiency for a variety of organic pollutants.

Fe–Decorated Nitrogen–Doped Carbon Nanospheres as an Electrochemical Sensing Platform for the Detection of Acetaminophen

In this work, Fe–decorated nitrogen–doped carbon nanospheres are prepared for electrochemical monitoring of acetaminophen. Via a direct pyrolysis of the melamine–formaldehyde resin spheres, the well–distributed Fe–NC spheres were obtained. The as–prepared Fe–NC possesses enhanced catalysis towards the redox of acetaminophen for abundant active sites and high–speed charge transfer. The effect of loading Fe species on the electrochemical sensing of acetaminophen is investigated in detail. The synergistic effect of nitrogen doping along with the above–mentioned properties is taken advantage of in the fabrication of electrochemical sensors for the acetaminophen determination. Based on the calibration plot, the limits of detection (LOD) were calculated to be 0.026 μM with a linear range from 0–100 μM. Additionally satisfactory repeatability, stability, and selectivity are obtained.

Molecular oxygen enhances H2O2 utilization for the photocatalytic conversion of methane to liquid-phase oxygenates

H₂O₂ is widely used as an oxidant for photocatalytic methane conversion to value-added chemicals over oxide-based photocatalysts under mild conditions, but suffers from low utilization efficiencies. Herein, we report that O₂ is an efficient molecular additive to enhance the utilization efficiency of H₂O₂ by suppressing H₂O₂ adsorption on oxides and consequent photogenerated holes-mediated H₂O₂ dissociation into O₂. In photocatalytic methane conversion over an anatase TiO₂ nanocrystals predominantly enclosed by the {001} facets (denoted as TiO₂{001})-C₃N₄ composite photocatalyst at room temperature and ambient pressure, O₂ additive significantly enhances the utilization efficiency of H₂O₂ up to 93.3%, giving formic acid and liquid-phase oxygenates selectivities respectively of 69.8% and 97% and a formic acid yield of 486 μmol_HCOOH·g_catalyst⁻¹·h⁻¹. Efficient charge separation within TiO₂{001}-C₃N₄ heterojunctions, photogenerated holes-mediated activation of CH₄ into ·CH₃ radicals on TiO₂{001} and photogenerated electrons-mediated activation of H₂O₂ into ·OOH radicals on C₃N₄, and preferential dissociative adsorption of methanol on TiO₂{001} are responsible for the active and selective photocatalytic conversion of methane to formic acid over TiO₂{001}-C₃N₄ composite photocatalyst.

The oxidation of methane to formic acid or related oxygenates relies on efficient reaction with H₂O₂. Here, the authors report a TiO₂-based catalyst to selectively form formic acid by using molecular O₂ additives to avoid unwanted side reactions.

Electronic Control of Traditional Iron-Carbon Electrodes to Regulate the Oxygen Reduction Route to Scale Up Water Purification

Shifting four-electron (4e^-) oxygen reduction in fuel cell technology to a two-electron (2e^-) pathway with traditional iron-carbon electrodes is a critical step for hydroxyl radical (HO^•) generation. Here, we fabricated iron-carbon aerogels with desired dimensions (e.g., 40 cm × 40 cm) as working electrodes containing atomic Fe sites and Fe₃C subnanoclusters. Electron-donating Fe₃C provides electrons to FeN₄ through long-range activation for achieving the ideal electronic configuration, thereby optimizing the binding energy of the *OOH intermediate. With an iron-carbon aerogel benefiting from finely tuned electronic density, the selectivity of 2e^- oxygen reduction increased from 10 to 90%. The resultant electrode exhibited unexpectedly efficient HO^• production and fast elimination of organics. Notably, the kinetic constant k_M for sulfamethoxazole (SMX) removal is 60 times higher than that in a traditional iron-carbon electrode. A flow-through pilot device with the iron-carbon aerogel (SA-Fe_0.4NCA) was built to scale up micropolluted water decontamination. The initial total organic carbon (TOC) value of micropolluted water was 4.02 mg L^-1, and it declined and maintained at 2.14 mg L^-1, meeting the standards for drinking water quality in China. Meanwhile, the generation of emerging aromatic nitrogenous disinfection byproducts (chlorophenylacetonitriles) declined by 99.2%, satisfying the public safety of domestic water. This work provides guidance for developing electrochemical technologies to satisfy the flexible and economic demand for water purification, especially in water-scarce areas.

Sulfone-Decorated Conjugated Organic Polymers Activate Oxygen for Photocatalytic Methane Conversion

Oxidizing CH₄ into liquid products with O₂ under mild conditions still mainly relies on metal catalysis. We prepared a series of sulfone-modified conjugated organic polymers and found that the catalyst with proper S^VI content (0.10) could drive O₂ →H₂ O₂ →⋅OH to oxidize CH₄ into CH₃ OH and HCOOH directly and efficiently at room temperature under light irradiation. Experimental results showed that after 4 h reaction, decomposition rate and residual amounts of H₂ O₂ were 81.21 % and 4.83 mmol g_cat ^-1 respectively, and CH₄ conversion rate was 22.81 %. Mechanism studies revealed that illumination could induce the homolytic dissociation of S=O bonds on catalyst to produce oxygen and sulfur radicals, where the ⋅O could adsorb and activate CH₄ , and the ⋅S could supply electrons for ¹ O₂ to generate H₂ O₂ and then for decomposing the H₂ O₂ into ⋅OH timely to oxidize CH₄ . This research provided a novel organic catalysis approach for oxygen activation and utilization.

Atomic-Layered Cu5 Nanoclusters on FeS2 with Dual Catalytic Sites for Efficient and Selective H2 O2 Activation

Regulating the distribution of reactive oxygen species generated from H₂ O₂ activation is the prerequisite to ensuring the efficient and safe use of H₂ O₂ in the chemistry and life science fields. Herein, we demonstrate that constructing a dual Cu-Fe site through the self-assembly of single-atomic-layered Cu₅ nanoclusters onto a FeS₂ surface achieves selective H₂ O₂ activation with high efficiency. Unlike its unitary Cu or Fe counterpart, the dual Cu-Fe sites residing at the perimeter zone of the Cu₅ /FeS₂ interface facilitate H₂ O₂ adsorption and barrierless decomposition into ⋅OH via forming a bridging Cu-O-O-Fe complex. The robust in situ formation of ⋅OH governed by this atomic-layered catalyst enables the effective oxidation of several refractory toxic pollutants across a broad pH range, including alachlor, sulfadimidine, p-nitrobenzoic acid, p-chlorophenol, p-chloronitrobenzene. This work highlights the concept of building a dual catalytic site in manipulating selective H₂ O₂ activation on the surface molecular level towards efficient environmental control and beyond.

Oxo dicopper anchored on carbon nitride for selective oxidation of methane

Selective conversion of methane (CH₄) into value-added chemicals represents a grand challenge for the efficient utilization of rising hydrocarbon sources. We report here dimeric copper centers supported on graphitic carbon nitride (denoted as Cu₂@C₃N₄) as advanced catalysts for CH₄ partial oxidation. The copper-dimer catalysts demonstrate high selectivity for partial oxidation of methane under both thermo- and photocatalytic reaction conditions, with hydrogen peroxide (H₂O₂) and oxygen (O₂) being used as the oxidizer, respectively. In particular, the photocatalytic oxidation of CH₄ with O₂ achieves >10% conversion, and >98% selectivity toward methyl oxygenates and a mass-specific activity of 1399.3 mmol g Cu⁻¹h⁻¹. Mechanistic studies reveal that the high reactivity of Cu₂@C₃N₄ can be ascribed to symphonic mechanisms among the bridging oxygen, the two copper sites and the semiconducting C₃N₄ substrate, which do not only facilitate the heterolytic scission of C-H bond, but also promotes H₂O₂ and O₂ activation in thermo- and photocatalysis, respectively.

Selective conversion of methane into value-added chemicals is a promising approach for utilization of hydrocarbon sources. Here the authors develop dimeric copper centers supported on graphitic carbon nitride (denoted as Cu₂@C₃N₄) with >10% conversion and >98% selectivity toward methyl oxygenates in both thermo- and photo- catalytic reactions.

Fe3O4 nanoparticles encapsulated in boron nitride support via N-doped carbon layer as a peroxymonosulfate activator for pollutant degradation: Important role of metal boosted C-N sites

Developing highly efficient and stable catalysts for peroxymonosulfate (PMS) based advanced oxidation processes (AOPs) are crucial in the field of environmental remediation. In this work, a facile encapsulated-precursor pyrolysis strategy was reported to prepare a competent PMS-activation catalyst, in which uniformly distributed Fe3O4 nanoparticles were firmly anchored on porous boron nitride (BN) nanosheets by N-doped carbon shell (NC layer). Taking advantage of strong metal-support interaction, the as-synthesized catalyst (BFA-500) could efficiently activate PMS to achieve 100% removal of 4-chlorophenol (4-CP) in 6 min, and the corresponding turnover frequency (TOF) value was 1-2 orders of magnitude higher than that of the benchmark homogeneous (Fe2+) and nanoparticle (Fe0 and Fe3O4) catalysts. Moreover, the well protected encapsulated structure of BFA-500 ensured the remarkable stability that could effectively resist the interference of complex water environment, including initial pH value, various inorganic ions and actual water, and its catalytic activity remained almost unchanged in 5 use-regeneration cycles. More importantly, the generation of O2•- and 1O2 radicals for the 4-CP removal in BFA-500/PMS system was ascribed to Fe3O4 boosted C-N sites containing pyridinic N, where electrons transferred from the embedded Fe3O4 nanoparticles to C-N sites to secure the PMS dissociation into reactive radicals. Overall, this work provided a promising way to design desired PMS-activation catalyst toward wastewater purification.

Catalyzed H2O2 decomposition over iron oxides and oxyhydroxides: Insights from oxygen production and organic degradation

Iron minerals, such as iron oxides and iron oxyhydroxides, are the main influential soil components in catalyzed hydrogen peroxide propagation (CHP). Due to their dual effects on H₂O₂ activation to produce reactive oxygen species (ROS) and invalid consumption to produce oxygen, the intrinsic reactivity of iron minerals toward H₂O₂ decomposition requires comprehensive investigations. Herein, six iron minerals (hematite, magnetite, maghemite, goethite, feroxyhyte, and ferrihydrite) for H₂O₂ decomposition were investigated by a combination of normalized kinetic rate constants of H₂O₂ decomposition (Nk_H2O2), O₂ production (Nk_O2), benzoic acid degradation (Nk_BA), and hexachloroethane degradation (Nk_HCA) over the surface area of each mineral. The results indicate H₂O₂ decomposition over iron minerals is a surface-related heterogeneous process. Hematite and goethite are the most promising minerals for environmental cleanup in terms of ROS production, because their H₂O₂ utilization efficiency for benzoic acid (BA) degradation (0.138 and 0.024 mol BA/mol H₂O₂ for hematite and goethite, respectively) are highest among the six iron minerals. Magnetite and maghemite are highly active for both H₂O₂ decomposition and O₂ production at neutral and basic pHs. The presence of organic compounds suppresses O₂ production by more than 60%, which favors H₂O₂ utilization. Ferrihydrite and feroxyhyte are considered as the problematic mineral for CHP due to that the two minerals acquire a high O₂ production and negligible ROS generation at all pHs. The results of this study provide new insights to increase the understandings of H₂O₂-iron mineral systems and guide the application of iron minerals in chemical oxidation technologies.

Elucidating the Mechanistic Origin of a Spin State-Dependent FeNx-C Catalyst toward Organic Contaminant Oxidation via Peroxymonosulfate Activation

Atomically dispersed metals on nitrogen-doped carbon matrices have attracted extensive interest in the removal of refractory organic pollutants. However, a thorough exploration of the particular structure for each active site and specific effects of these sites still remains elusive. Herein, an Fe-pyridinic N₄ structure in a single-atom catalyst (FeN_x-C) was constructed using a facile pyrolysis strategy, and it exhibited superior catalytic activity in peroxymonosulfate (PMS) activation toward organic contaminant oxidation. The various Fe species and relative amounts of each Fe site in the FeN_x-C catalyst were validated using X-ray absorption spectroscopy and ⁵⁷Fe Mössbauer spectroscopy, which showed critical dependencies on the precursor ratio and calcination temperature. The positive correlations between relative content of high-spin state species (Fe^II and Fe^III) and catalytic performance were found to determine the reactive species generation and electron transfer pathway in the FeN_x-C/PMS system. Moreover, catalytic performance and theoretical calculation results revealed that Fe^II-N₄ in the high-spin state (S = 2) tends to activate PMS to form sulfate and hydroxyl radicals via a one-electron transfer process, while the Fe^III-N₄ moiety (S = 5/2) is prone to high-valent iron species generation with lower free energy. Benefiting from finely tuned active sites, a single-atom FeN_x-C catalyst achieved favorable applicability in actual wastewater treatment with efficient resistance of the common water matrix. The present work advances the mechanistic understanding of spin state-dependent persulfate activation in single-atom catalysts and provides guidance to design a superior catalyst based on spin state descriptions.

Synergic Photocatalytic CH4 Conversion to C1 liquid products using Fe oxides species-modified g-C3N4

CH4 direct conversion into high valued liquid oxygenated products at mild experimental conditions is of great significance to solve both environment and energy problems. Although great effort has been made,...

Selective oxidation of CH4 to valuable HCHO over a defective rTiO2/GO metal-free photocatalyst

A specially designed metal-free rTiO2/GO catalyst retarded the recombination of photo-generated electrons and holes and improved photocatalytic CH4 conversion performance.

Green Carbon Science: Efficient Carbon Resource Processing, Utilization, and Recycling Towards Carbon Neutrality

Green carbon science is defined as "Study and optimization of the transformation of carbon containing compounds and the relevant processes involved in the entire carbon cycle from carbon resource processing, carbon energy utilization, and carbon recycling to use carbon resources efficiently and minimize the net CO2 emission." [1] Green carbon science is related closely to carbon neutrality, and the relevant fields have developed quickly in the last decade. In this Minireview, we proposed the concept of carbon energy index, and the recent progresses in petroleum refining, production of liquid fuels, chemicals, and materials using coal, methane, CO2, biomass, and waste plastics are highlighted in combination with green carbon science, and an outlook for these important fields is provided in the final section.

Dihydroxyacetone valorization with high atom efficiency via controlling radical oxidation pathways over natural mineral-inspired catalyst

Diminishing fossil fuel resources and calls for sustainability are driving the urgent need for efficient valorization of renewable resources with high atom efficiency. Inspired from the natural goethite mineral with Mn paragenesis, we develop cost-effective MnO2/goethite catalysts for the efficient valorization of dihydroxyacetone, an important biomass-based platform molecule, into value-added glycolic acid and formic acid with 83.2% and 93.4% yields. The DHA substrates first undergo C-C cleavage to selectively form glycolic acid and hydroxymethyl (·CH2OH) radicals, which are further oxidized into formic acid. The kinetic and isotopic labeling experiments reveal that the catalase-like activity of MnO2 turns the oxidative radicals into oxygen, which then switches towards a hydroxymethyl peroxide (HMOO) pathway for formic acid generation and prevents formic acid over-oxidation. This nature-inspired catalyst design not only significantly improves the carbon efficiency to 86.6%, but also enhances the oxygen atom utilization efficiency from 11.2% to 46.6%, indicating a promising biomass valorization process.

Regulating Local Electron Density of Iron Single Sites by Introducing Nitrogen Vacancies for Efficient Photo-Fenton Process

The activity of heterogeneous photocatalytic H₂ O₂ activation in Fenton-like processes is closely related to the local electron density of reaction centre atoms. However, the recombination of electron-hole pairs arising from random charge transfer greatly restricts the oriented electron delivery to active center. Here we show a defect engineered iron single atom photocatalyst (Fe₁ -N_v /CN, single Fe atoms dispersed on carbon nitride with abundant nitrogen vacancies) for the activation of H₂ O₂ under visible light irradiation. Based on DFT calculations and transient absorption spectroscopy results, the engineered nitrogen vacancies serve as the electron trap sites, which can directionally drive the electrons to concentrate on Fe atoms. The formation of highly concentrated electrons density at Fe sites significantly improves the H₂ O₂ conversion efficiency. Therefore, the optimized single atom catalyst exhibiting a higher ciprofloxacin degradation activity, which was up to 18 times that of pristine CN.

Cu,Zn Dopants Boost Electron Transfer of Carbon Dots for Antioxidation

Enzyme-mimicking nanomaterials for antioxidative therapy is a promising star to treat more than 200 diseases or control their progressions through scavenging excessive reactive oxygen species (ROS), such as O₂^•- and H₂ O₂ . However, they can inversely produce stronger ROS (e.g., •OH) under many disease conditions (e.g., low pH for myocardial ischemia). Herein, a biocompatible -Cu-O-Zn- bimetallic covalent doped carbon dots (CuZn-CDs) processing both catalase (CAT) and superoxide dismutase activities are reported, mainly because of their abundant electrons and the excellent electron transfer abilities. In addition, Cu dopant helps to balance the positive charge at Zn dopant resulting from low pH, enabling CuZn-CDs to still process CAT ability rather than peroxidase ability. Benefiting from it, CuZn-CDs exhibit sufficient in vitro ROS scavenging ability and cardiomyocyte protective effect against ROS-induced damage. In vivo results further demonstrate that CuZn-CDs can protect the heart from ischemia-reperfusion injury. In addition to antioxidative therapy, the rapid renal clearance and low toxicity properties of CuZn-CDs in animal model reveal high biocompatibility which will facilitate clinical use.