Catalysis Letters最新文献

Electrochemical reduction of CO₂ to valuable C1 products is a promising strategy for carbon mitigation and renewable energy storage. Copper-based single-atom catalysts have garnered significant attention due to their exceptional catalytic performance for CO₂ reduction reactions. In this study, we used density functional theory to systematically investigate the effect of heteroatom (B, O, S) doping on Cu–N–C SACs. By adjusting the coordination environment of Cu active sites, we aimed to enhance the catalytic efficiency and selectivity for C1 products, such as CO, HCOOH, CH₃OH, and CH₄. Our results reveal that doping with heteroatoms significantly modulates the electronic structure of the Cu active sites, thereby influencing CO₂ adsorption, intermediate stabilization, and reaction pathways. The S-doped Cu-N₂S₂-1 and Cu-N₂S₂-2 catalysts exhibit superior CO selectivity, while B-doped Cu-N₂B₂-2 and Cu-N₁B₃ catalysts demonstrate high HCOOH production efficiency. The Cu-N₂B₂-1 catalyst shows optimal activity for multi-electron products (CH₃OH and CH₄), while Cu-N₁B₃ and Cu-N₀O₄ display superior selectivity for CH₃OH and CH₄, respectively. Stability analyses confirm the structural and electrochemical robustness of these catalysts under operating conditions. This work provides critical insights into the coordination engineering of Cu SACs and establishes a rational design strategy for high-performance catalysts in sustainable CO₂ conversion.

A green and efficient method has been developed for the synthesis of chromene analogues via atom-economical heterocyclization. This methodology enables ultrarapid and sustainable synthesis of heterocyclic analogues, without generating byproducts and multiple reuse cycles of the nanocatalyst. This process involves the reaction of different aldehydes, 4-hydroxycoumarin, and malononitrile in water using 8-hydroxyquinoline-5-sulfonic acid@CoFe₂O₄ (HQS@CoFe₂O₄) as a magnetic catalyst under mild reaction conditions (70 °C). The procedure offers several advantages, including operational simplicity, high yields (97%), short reaction times, and no need for laborious purification steps. The catalyst demonstrates excellent activity in aqueous media and its easy preparation and straightforward magnetic separation make it a practical and effective heterogeneous system. Notably, the catalyst can be reused multiple times with minimal loss of performance. The synthesized chromene analogues were characterized by melting point, IR, and ¹H NMR spectroscopy, confirming their successful formation.

Graphical Abstract

Developing highly active and stable non-precious-metal electrocatalysts for the oxygen evolution reaction (OER) is essential for efficient green hydrogen production. However, monometallic catalysts exhibit poor stability and high overpotentials under high current densities. Therefore, the development of multi-metallic catalysts has become a focus of attention. Herein, we report a NiCoFeS/NF catalyst that exhibits higher OER activity in alkaline solution compare with commercial RuO₂-based catalysts. The synthesized NiCoFeS/NF catalyst delivers a current density of 100 mA cm^− 2 at a low overpotential of 280 mV and exhibits a Tafel slope of 49 mV dec^− 1, reflecting its favorable kinetics. Furthermore, the NiCoFeS/NF catalyst exhibited a long-term stability over 120 h, ensuring its potential for practical applications. Detailed characterizations revealed that sulfur incorporation not only creates additional active sites but also induces the self-unfolding of nanoparticles into nanosheets, thereby enlarging the electrochemically active surface area (ECSA).

Graphical Abstract

Hydrogenation of organic carbonates on heterogeneous catalysts is one of the ways of indirect conversion of carbon dioxide, which is essential for addressing the urgent problem of decarbonization. Cu-based catalysts are the most widely used in hydrogenation, but their properties strongly depend on the characteristics of the heterogeneous carriers used. Although SiO₂-based catalysts are the most extensively studied, it is of interest to develop catalysts based on new types of carriers such as MOFs, COFs and PAFs. In the current work, a series of copper-based catalysts with different metal contents (2, 5, 10, 30 wt%) based on porous aromatic framework PAF-30 and its amino-functionalized derivative PAF-30-NH₂ were synthesized and investigated in the hydrogenation of ethylene carbonate. The influence of reaction temperature, hydrogen pressure, concentration of ethylene carbonate in its solution in THF, copper content in the catalysts and reduction conditions on the activity of the catalysts was systematically studied. A high activity of 940 mg_EC g_cat⁻¹ h⁻¹ was attained with 30Cu-PAF-30-NH₂ catalyst at 200 °C and 4 MPa H₂ in 4 h.

Graphical Abstract

The widespread occurrence of pharmaceutical pollutants, particularly ciprofloxacin, in aquatic environments threatens ecosystem health and promotes bacterial resistance to antibiotics. Conventional wastewater treatments fail to meet the standards (< 0.1 µg/L), while TiO₂ photocatalysts show limited visible-light activity because of their wide band gaps (3.0-3.2 eV). In this study, Co-doped Co_xSr_0.7−xMn_0.3Al_0.4Fe_1.6O₄ (X = 0,0.2) spinel ferrites were synthesized, and X-ray diffraction confirmed a cubic spinel ferrite structure, with cobalt doping reducing the crystallite size (from 28.371 to 20.488 nm). FTIR spectroscopy revealed the incorporation of Co through the peak shifts. The Co-doped catalyst exhibited enhanced properties: BET surface area increased from 6.63 to 32.14 m²/g, pore volume from 0.86 to 1.29 cm³/g, and optical band gap narrowed from 2.82 to 2.61 eV. Ciprofloxacin degradation improved from 53.65% to 100% in 70 min, with a quantum efficiency of 1.85 × 10⁻⁶ molec/photon and a space-time yield of 9.24 × 10⁻⁸ molec/ph. Kinetic analysis showed first-order behaviour (k₁ = 0.02411 min⁻¹, R² = 0.98864). The catalyst degraded Rhodamine B (82%), Methylene Blue (71.81%), tetracycline (66.82%), and sulfamethoxazole (42%) with hydroxyl radicals as the primary oxidisers, maintaining 91.66% efficiency after five cycles.

Graphical Abstract

Biomass, as a renewable and environmentally friendly energy source, has attracted widespread attention in recent years. Among biomass-derived platform molecules, 5-hydroxymethylfurfural (HMF) is particularly important due to its potential to be converted into a variety of high-value chemicals. The development of green and efficient catalysts is crucial for the selective conversion of HMF. In this study, industrial solid waste coal fly ash (CFA) was utilized as a support to prepare a series of iron–nickel bimetallic catalysts via a simple grinding method for the catalytic hydrogenolysis of HMF to biofuel 2,5-dimethylfuran (DMF), a promising biofuel. The structural and surface properties of the catalysts were characterized by XRD, TG, XPS, and TEM. The effects of Fe–Ni composition, reaction temperature, catalyst dosage, and reaction time on HMF conversion and DMF selectivity were systematically investigated. The results revealed that the optimized catalyst achieved complete conversion of HMF and a DMF selectivity of up to 97.4% under mild conditions. Furthermore, the incorporation of Fe significantly enhanced the hydrogenation selectivity of Ni, demonstrating a strong synergistic effect in the bimetallic system. This work provides a sustainable approach for biomass valorization and highlights the potential of repurposing industrial waste materials for catalytic applications.

Graphical Abstract

Electrochemical ammonia treatment has garnered significant interest due to its operational simplicity, environmental compatibility, and adaptability to diverse conditions. A key challenge remains the development of robust, highly active, and cost-effective anodes for ammonia oxidation. Herein, we report a ternary metal oxides electrode for ammonia oxidation reaction, fabricated by integrated electrochemical deposition and thermal treatment. The resulting NiCoCu oxides electrode achieves a net current density of 75.2 mA/cm² at 1.62 V vs. RHE for ammonia oxidation. The electrolytic cell exhibits a Faradaic efficiency of ~ 24% and enables ~ 93% ammonia removal after 24 h of operation. Density functional theory (DFT) analysis reveals that incorporating Ni and Co modulates the catalyst’s electronic structure, inducing surface charge redistribution and optimizing adsorption strength of reaction intermediates. This work establishes a versatile strategy for fabricating NiCoCu oxides electrode with high efficacy in electrocatalytic ammonia oxidation.

Graphical Abstract

This study provides a ternary metal oxides electrode for ammonia oxidation reaction, fabricated by integrated electrochemical deposition and thermal treatment.

The introduction of a second metal into Au/TS-1 can increase the number of active sites and control the size of metal particles to enhance catalytic activity. In this study Au-Fe bimetallic catalyst Au-Fe/TS-1 was prepared by the deposition-precipitation (DP) method, the structure and morphology of the catalyst were characterized by XRD, BET, and HRTEM. The effects of Fe source (such as Fe(NO₃)₃, Fe₂(SO₄)₃, NaFeEDTA) and Fe/Au ratio on propylene epoxidation performance were systematically investigated. The facile hydrolysis of Fe³⁺ and the absence of ligand coordination resulted in substantial coating of the TS-1 surface with Fe(OH)₃ which severely impaired propylene oxide (PO) selectivity and promoted the peroxidation reaction. However, using NaFeEDTA as Fe source can significantly inhibit excessive Fe deposition and the Au nanoparticles of Au-Fe/TS-1 is around 2 nm (smaller than the 3 nm in Au/TS-1). The synergistic effect of Au-Fe enhances the epoxidation activity of the catalyst, thereby increasing the rate of PO formation. Specifically, the optimal catalyst, Au-Fe_0.2(E)/TS-1(using NaFeEDTA as Fe source), achieved a maximum PO formation rate of 146 g_PO·h⁻¹·kg_Cat⁻¹ at 200 °C (significantly higher than 96 g_PO·h⁻¹·kg_Cat⁻¹ of Au/TS-1), with PO selectivity exceeding 90%. These findings provide valuable insights for the rational design and development of more efficient Au-M bimetallic catalysts.

Graphical Abstract

Emerging pollutants such as methylparaben (MePB) are increasingly detected in aquatic environments and require effective removal strategies. This study reports the synthesis of Ni–Ce (x: y) composite catalysts as thin films via ultrasonic spray pyrolysis and evaluates their performance in catalytic ozonation. Although conventional ozonation resulted in complete MePB degradation, it exhibited limited mineralization efficiency. In contrast, the integration of Ni–Ce films significantly improved total organic carbon (TOC) removal, with the Ni–Ce (50:50) composition achieving the highest mineralization (52.1%) after 120 min, compared to 35.4% with ozone alone. The TOC removal efficiency followed the trend: Ni–Ce (50:50) > Ni–Ce (25:75) > Ni–Ce (75:25) ≈ Ni–Ce (10:90) > Ni–Ce (5:95). X-ray photoelectron spectroscopy (XPS) revealed that the enhanced catalytic activity was associated with higher Ce³⁺ content and increased oxygen vacancy concentrations, which facilitated the formation of reactive oxygen species (ROS), including hydroxyl radicals (·OH), superoxide anions (·O₂⁻), and singlet oxygen (¹O₂). The Ni–Ce (50:50) film maintained stable performance across five successive reaction cycles, confirming its reusability. Additionally, phytotoxicity assays using Lactuca sativa seeds demonstrated the treated effluents’ non-toxic nature, supporting the process’s environmental safety.

Graphical Abstract