In situ synthesis of a bimetallic Co/Ni-BDC MOF for dual-function CO2/CH4 adsorption and alkene oxidation catalysis

The acceleration of industrialization has driven the increased emission of volatile organic compounds (VOCs), posing significant threats to both the ecological environment and public health. The deficiency of reactive oxygen species fundamentally restricts the low-temperature catalytic toluene combustion in transition-metal oxide catalysts. Herein, we report a strategy for intelligently designing active Cu+-Ov-Ti ensembles by coupling isolated Cu with adjacent oxygen vacancy, which can synergistically activate chemisorbed O2 into reactive superoxide species (O2-). The defective Cu/TiO2-x catalyst exhibited remarkable catalytic performance for toluene oxidation, achieving a T90 of 225 °C, significantly 100 °C lower than that of the pristine Cu/TiO2 catalyst. The low coordination geometry and electron transfer within Cu+-Ov-Ti ensembles synergistically activated O2 to form the Cu-(O-O)ad-Ti bridged superoxide O2- intermediate with an elongated O═O bond. In addition, the distinctive Cu-(O-O)ad-Ti bridging structure with localized electrons facilitated the chemisorbed O2 dissociation into electrophilic monatomic O- species, which subsequently nucleophilically attack the methyl C-H of toluene. These benzyl alcohol-derived Ph-CH2-O- intermediates can be readily and flexibly converted into reactive benzaldehyde and benzoic acid species, which were available for subsequent aromatic ring-opening reactions. This study not only advances mechanistic insights into the Cu+-Ov-Ti ensembles and electrophilic O- species in toluene catalytic oxidation but also establishes a design Cu+-Ov-Ti principle for engineering efficient VOC elimination catalysts.

To effectively treat refractory azo dye wastewater, microwave advanced catalytic oxidation technology was adopted to degrade the model pollutant methyl orange using activated carbon fiber (ACF)/CuO as the catalyst and potassium persulfate (K2S2O8) as the oxidant. The optimized experimental parameters and the degradation pathway of methyl orange were determined. The results showed that when the microwave power was 500W, the irradiation time was 2min, the dosage of potassium persulfate was 0.6g/L, and the dosage of ACF/CuO was 10g/L, the removal rate of methyl orange solution was close to 100%, the COD removal rate was 89.65%, and the TOC removal rate was 72.36%. Mechanism analysis indicated that the double bond was broken to generate acid and p-nitrophenol, which were gradually degraded to benzene and phenol under the oxidation of sulfate radical. Subsequently, the benzene and phenol underwent chain cleavage to form maleic anhydride, and part of the benzene, phenol, and the generated maleic anhydride were ultimately degraded to water and carbon dioxide.

The low-temperature direct conversion of ethane is more appealing for the utilization of shale gas. Dual-atom catalysts have attracted considerable attention due to their unique cooperative effects. Herein, we report a porous organic polymer-supported Rh1-Cu1 dual-site catalyst (Rh1-Cu1@POPs-PPh3) for the selective oxidation of ethane to ethanol, acetaldehyde, and acetic acid with auto-selective oxygen mechanism. The optimized Rh1-Cu1 centers deliver a productivity of ca. 250mol molRh -1 h-1 based on Rh with 65% acetaldehyde selectivity at 423 K, representing a four-fold improvement over the single-Rh-site catalyst. Through isotopic labeling and in situ characterizations, we uncover an auto-selective oxygen source mechanism in which dehydrogenated species of ethane with different grades possess self-selectivity for the combined oxygen source. Oxygen species derived from O2 activate ethane and subsequently couple with the ethyl fragment to produce ethanol. While OH radicals from H2O dissociation react with ethyl intermediates from ethane dehydrogenation to yield acetaldehyde. Concurrently, oxygen species recombine with reactive hydrogen species to regenerate new H2O, completing the catalytic oxidation cycle. The density functional theory (DFT) calculations reveal that the Rh-Cl-Cu configuration lowers the lowest unoccupied molecular orbital (LUMO) energy of Rh1, thereby strengthening adsorbate-metal interactions, weakening the C─H bond, and facilitating its activation.

Accurate and reliable nitrite (NO2-) detection is crucial for food safety but remains challenging. Herein, we develop a triple-signal sensing strategy utilizing bifunctional carbon dot (CD) nanozymes for NO2- analysis in diverse food matrices. CDs with blue fluorescence and photoresponsive oxidase-mimicking activity are successfully synthesized by a simple one-step hydrothermal treatment with citric acid monohydrate (CA) and triethanolamine (TEA) as precursors. The oxidase-mimicking property enables efficient catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) from colorless to blue ox-TMB. Capitalizing on the specific diazotization reaction between NO2- and o-phenylenediamine (OPD)/ox-TMB, the engineered sensor delivers ratiometric fluorescence, ratiometric colorimetric, and photothermal triple-signal outputs, displaying high performance in selectivity and anti-interference capability. The linear detection ranges for NO2- are 0.5-400 μM in ratiometric fluorescence sensing, 0.5-100 μM in ratiometric colorimetric sensing, and 5-100 μM in photothermal sensing, with corresponding limits of detection of 0.23 μM, 0.19 μM, and 1.43 μM, respectively. Furthermore, by leveraging the distinct color transitions from ratiometric fluorescence and colorimetric responses, a dual-modality sensing platform assisted by smartphones is engineered to achieve convenient, visual, and on-site NO2- detection in food samples. Notably, the integrated photothermal detection specifically overcomes the limitations of conventional optical methods for analyzing colored or autofluorescent samples, while the cross-validation capability of the multimodal strategy ensures reliable and stable results. This synergy provides a comprehensive and promising solution for the accurate and robust monitoring of NO2- in multiple types of food matrices.

Heterogeneous sulfate radical-based advanced oxidation process for the efficient pharmaceutical wastewater treatment: Performance, practicability, and mechanism.

Insights into the role and pathways of oxygen in NO catalytic oxidation over activated coke at sub-zero temperatures

Sewage sludge valorization into iron-carbon composites for environmental remediation: A critical review on synthesis, synergy, and sustainability.

Catalytic electrochemical oxidation of a bio-model, 5-hydroxymethyl furfural, toward a circular plastic economy

Emerging catalysts for catalytic ozone advanced oxidation in water purification: Metal-organic frameworks and their derivatives.

Catalytic oxidation of toluene: mechanisms, deactivation, mitigation, and regeneration

Enhanced Room-Temperature catalytic oxidation of formaldehyde via A novel Na-Doped MnO2/Co3O4 Catalyst: Oxygen vacancy engineering and application in Aqueous-Gas hybrid purification system

Cu-Co oxides supported on porous minerals for catalytic oxidation of butyl acetate: Particle dispersion, catalytic performance, and oxidation mechanism

Matching effect of surface hydroxyl content and Cu loading: Formation of CuO clusters and their determinant role in catalytic oxidation of AsH3

Efficient catalytic oxidation of chlorobenzene over Fe2(SO4)3/TiO2 catalysts with Brønsted acid sites

Trace Cr(VI)-triggered activation of iron-rich sludge ceramsite/peroxymonosulfate for efficient catalytic oxidation of tetracycline hydrochloride

Exploring novel-type nanozymes with programmatically manipulated enzyme-mimicking activity for targets' accurate identification and multimodal biosensing represents one of the most fascinating yet challenging research frontiers. Herein, taking DNAs as programmable biotemplates, we prepared bimetallic PtAg nanocluster-zyme via simple in situ reduction. Among them, the A20-templated PtAg nanozyme exhibited superior peroxidase-like (POD-like) activity, as confirmed by optical analyses, steady-state kinetics, and electron paramagnetic resonance spectroscopy, with •O2- and •OH identified as the primary reactive oxygen species. Taking Pt-AMP with the Pt-N4 coordination structure as representative, pluralistic DFT calculations were performed. Corresponding results manifested the superior affinity of nanozyme for H2O2 and TMB, the elongated O-O bond length of H2O2 and facilitated electron-transfer ability at the catalytic core. Subsequently, by harnessing the efficient catalytic oxidation of TMB and AR, we fabricated a colorimetric-photothermal-fluorescent trimodal sensing platform for assessing total antioxidant capacity and alkaline phosphatase activity. Superior to previous single/dual-modal biosensors, this work demonstrated significant advantages in sensitivity, reliability, and accuracy, and showed acceptable adaptability in diversified real matrices (human serum, tablets, and beverages). Furthermore, we fabricated target-responsive cascade logic circuits by virtue of the proper incorporation of trimodal signals and Boolean logic, and achieved the smart recognition of targets. This work not only provided a mild, simple, and efficient biotemplated approach for the programmable tuning of noble-metal nanozymes' catalytic activity but also enlightened novel pathways for the operation of logic-empowered intelligent biosensors.

Efficient photothermal catalytic oxidation of methane over acid-activated α-MnO2: Environmental implications and defect-mechanism insights.

Tungsten–Doped TiO2 for photothermal catalytic oxidation of gaseous ammonia: Synthesis, performance, and mechanism

Regulating the properties of TiO2-WO3 solid acid catalysts for catalytic oxidation of chlorine and sulfur-containing VOCs