Search Results (5,910)

Municipal sewage sludge was used to prepare sewage sludge pyrolysis char (SS-PC). The effects of pyrolysis temperature on the morphology and structure of SS-PC were investigated, and the performance of SS-PC-800, prepared at 800 °C, for promoting gas production from corn stover pyrolysis was evaluated in a fixed-bed reactor. The results suggested that adding SS-PC-800 promoted the pyrolysis of corn stover and reduced the activation energy required for thermal decomposition. A further comparison of five metal oxides indicated that CaO had the most pronounced effect on H₂ formation under the tested conditions. A synergistic effect was observed when reactive CaO was introduced into SS-PC. At a pyrolysis temperature of 800 °C, when the mass ratio of CaO to SS-PC-800 was 2:3 and the mass ratio of mixed catalyst to corn stover was 1:5, the H₂ yield was 26.5% higher than that obtained from corn stover pyrolysis alone. In this study, SS-PC was employed as a catalytic material, and the synergistic interaction between its catalytic components and CaO effectively enhanced H₂ production during biomass pyrolysis. These findings can provide a useful reference for the resource utilization of municipal sludge and the development of catalysts for biomass thermochemical conversion. Full article

Methods for the preparation of aluminum hydroxides and alumina-supported catalysts through the interaction of activated Al–In–Ga alloys with water were developed. Bayerite was obtained from an alloy containing 99.0% Al + 0.5% In + 0.5% Ga at 303 K, while pseudoboehmite was synthesized from 90% Al + 5% In + 5% Ga at 363 K. The maximum specific surface area of aluminum oxide reached 700 m²/g. Dehydration of aluminum hydroxides proceeds via a sigmoidal mechanism with induction, acceleration, and deceleration stages. The dehydration rate increases with calcination temperature. Kinetic analysis revealed both kinetic and diffusion-controlled transformation regions for pseudoboehmite and bayerite. Transformation of pseudoboehmite into γ-Al₂O₃ at 523–673 K preserves a high specific surface area of 630–640 m²/g. Two platinum deposition methods were proposed: synthesis in the presence of soluble platinum salts and incorporation of Pt into the Al–Ga–In alloy followed by reaction with water. Alongside metallic Pt, Ptδ⁺, Pt²⁺, and Pt⁴⁺ species were detected and reduced to Pt⁰ at 900 K. Alumina–platinum catalysts showed high activity in cyclohexane dehydrogenation. A Zn–Al catalyst for methanol decomposition was developed, providing up to 70% H₂ in gaseous fuel and complete methanol conversion at 573 K. Full article

Sustainable water remediation requires catalytic strategies that remove contaminants efficiently while reducing chemical input, byproduct formation, and ecological disturbance. Conventional radical-dominated advanced oxidation processes can rapidly degrade pollutants, but their reliance on high oxidant dosages and freely diffusing reactive oxygen species often causes matrix quenching, non-selective oxidation, low oxidant utilization, and potential ecological risks. Mild interfacial catalysis provides a materials-chemistry strategy to regulate oxidative intensity and direct contaminant transformation under environmentally relevant conditions. In this review, mild catalysts are defined by pathway-selective, interfacially confined, and environmentally compatible oxidation rather than by low dosage alone. Representative non-radical or low-intensity pathways, including singlet oxygen generation, surface-mediated electron transfer, high-valent metal–oxo species, and direct oxidative transfer processes, are discussed in relation to active-site structure, oxidant utilization, matrix tolerance, and byproduct control. We further summarize how coordination environments, defect chemistry, heteroatom configurations, nanoconfinement, and immobilized interfaces regulate reactive-species formation and interfacial charge transfer. Key material platforms, including single-atom catalysts, heteroatom-doped carbons, defect-engineered oxides, catalytic membranes, hydrogels, and floating or immobilized composites, are evaluated from mechanistic and application-oriented perspectives. Finally, catalyst regeneration, cost, microbial community responses, algae–bacteria balance, ecotoxicity, and long-term safety are discussed to guide sustainable aquatic ecosystem restoration. Full article

Biogenically recovered mixed metal(loid) sulfides (BPS) obtained from metallurgical effluents were evaluated as sustainable photocatalysts for the solar-driven degradation of Rhodamine B (RhB). The material, recovered using biogenic sulfide produced by sulfate-reducing bacteria in an upflow anaerobic sludge bed reactor, was mainly composed of Sb₂S₃ and Bi-containing sulfide phases and exhibited a fibrous morphology and a narrow direct band gap of 1.306 eV. Under solar irradiation, BPS achieved RhB degradation efficiencies above 98% under the evaluated conditions (0.8 g L⁻¹ catalyst and 5 mg L⁻¹ dye), consistently outperforming reagent-grade Sb₂S₃. Photocatalytic degradation followed pseudo-first-order kinetics (R² > 0.90), and the apparent reaction rate constant was more than five times higher than that of the reference material under the best-performing conditions. A preliminary reusability assessment and post-reaction characterization after three photocatalytic cycles revealed no significant morphological or compositional changes in BPS. These results demonstrate that waste-derived metal(loid) sulfides recovered through a biogenic process can serve as effective solar photocatalysts, highlighting a promising circular-economy strategy for transforming metallurgical residues into value-added materials for water remediation. Full article

Nanostructured catalysts have become a core component of energy conversion in electrocatalysis and photocatalysis; however, successfully translating their performance from laboratory scale to industrial applications remains a long-standing challenge. This paper provides a critical assessment of the field, systematically tracing the entire development trajectory from catalyst design to practical application. We focus on five major classes of catalysts—monometallic catalysts, bimetallic/multimetallic alloy catalysts, metal compound catalysts, carbon-based composite catalysts, and single-atom catalysts—and explore synthetic strategies for achieving precise structural control, including hydrothermal/solvothermal methods, electrodeposition, template-assisted and MOF-derived syntheses, high-temperature pyrolysis, and post-treatment defect engineering. This paper delves into the mechanisms and performance descriptors governing the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), urea oxidation, photocatalytic water splitting, and CO₂ reduction. Based on the above analysis, this paper lays the mechanistic foundation for five core strategies to improve catalyst performance: morphology control, elemental doping, heterostructure and interface engineering, defect and vacancy engineering, and support modification. Furthermore, this paper provides an in-depth evaluation of the applications of these catalysts in water splitting, CO₂ valorization, fuel cells, metal–air batteries, and energy-saving electrolysis, with a particular focus on earth-abundant alternatives to precious metals. We argue that in many well-studied reactions, intrinsic activity may no longer be the primary bottleneck restricting their development; instead, the core challenge now lies in maintaining excellent catalytic performance under harsh and industrially relevant conditions, especially under high-current densities, impurity-containing feed systems, and long-term operating conditions. In response to this shift in research focus, this paper clearly identifies the key obstacles hindering the industrial application of catalysts and proposes practical directions for future research. Full article

The practical application of Li–O₂ batteries is severely hindered by parasitic reactions on the cathode side, which generally lead to large charging over-potentials and degraded cyclic performance. To address this issue, it is essential to integrate high-efficiency catalysts into conventional carbon-based electrodes. Herein, we report a novel La_0.85Ca_0.15Cr_0.85O₃@Ru (LCC@R) hybrid catalyst with an ultralow Ru loading (6.55 wt.%), synthesized via a facile sol-gel combined with in-situ reduction-exsolution method. Mono-dispersed and ultrafine Ru nanocrystals (2–5 nm) are uniformly anchored on the LCC substrate and serve as the catalytically active sites. The Li–O₂ battery with the LCC@R catalyst exhibits a low charge potential of 3.75 V at a current density of 50 mAg⁻¹ with limited capacity of 500 mAhg⁻¹. Impressive cyclic stabilities of up to 80 cycles (at 1000 mAhg⁻¹) and 15 cycles (at 2000 mAhg⁻¹) are achieved. Moreover, a large specific capacity of 8630 mAhg⁻¹ is delivered at 50 mAg⁻¹. Mechanistic studies reveal that the intermediate discharge product LiO₂ can be absorbed on LCC@R, thereby inhibiting the parasitic reactions induced by LiO₂ attack on carbon. The as-prepared LCC@R hybrid material is a promising cathode catalyst for constructing long-cycle-life and low-over-potential Li–O₂ batteries. Full article

Developing cost-effective alternatives to platinum-based catalysts remains paramount for commercializing anion exchange membrane fuel cells (AEMFCs). We report a metal-free nitrogen-doped carbon catalyst derived from a rationally designed polyurea–polyimine copolymer that outperforms commercial 20 wt% Pt/C in superior relative durability and methanol tolerance. Strategic integration of polyurea’s pore-forming capability with polyimine’s thermal stability enabled the synthesis of a catalyst (NC-1000N) featuring ultrahigh surface area (1276.5 m² g⁻¹), optimal nitrogen speciation (20.5% pyridinic-N, 45.3% graphitic-N), and enhanced graphitization, which improves the electrical conductivity of catalysts. NC-1000N exhibited exceptional oxygen reduction performance with an onset potential of 0.96 V, almost four-electron selectivity (n = 3.87), a medium Tafel slope (105 mV dec⁻¹), and minimal charge transfer resistance (46.74 Ω). When evaluated in single-cell AEMFCs, NC-1000N delivered a peak power density of 372.1 mW cm⁻², which is 26% higher than Pt/C at equivalent loading, while demonstrating superior stability (94.8% retention after 7 h) and complete methanol tolerance. Systematic pyrolysis temperature optimization (800–1000 °C) revealed critical structure–property relationships governing catalyst evolution from disordered precursor to highly graphitic, nitrogen-enriched carbon with precisely engineered active sites. This work establishes polymer-derived carbons and provides design principles for scalable synthesis of high-performance metal-free electrocatalysts for sustainable energy conversion technologies. Full article

Two-dimensional heterostructures have attracted considerable attention in electrocatalytic hydrogen evolution due to their pronounced interfacial effects, tunable electronic properties, and large specific surface areas. In this work, two representative oxygen-terminated transition metal carbides (MXenes) and three typical transition metal dichalcogenides (TMDs) were selected to construct six heterostructures. Using first-principles density functional theory (DFT) calculations, their binding energies, structural stability, electronic structures, and HER catalytic performance were systematically investigated. The results showed that all heterostructures possessed good thermodynamic stability and favorable electronic properties. In particular, SnS₂/Ti₂CO₂, SnSe₂/Ti₂CO₂, SnTe₂/Ti₂CO₂, and SnTe₂/Zr₂CO₂ exhibited near-optimal hydrogen adsorption Gibbs free energy, indicating excellent HER activity. Moreover, the variation in Gibbs free energy of hydrogen adsorption from isolated monolayers to heterostructures could be effectively correlated with the work function difference. The predicted trends provided a useful descriptor for catalytic performance. Overall, this study provides theoretical insights into the rational design of efficient, advanced HER catalysts and contributes to the advancement of sustainable energy conversion technologies. As this work is based solely on first-principles calculations, the predicted catalytic activity of the heterostructure should be regarded as a theoretical prediction and awaits experimental confirmation. Full article

The influence of carbon support and Cu loading on the structural, surface, and catalytic properties of Cu-based catalysts for furfural hydrogenation was systematically investigated. Two activated carbons with distinct textural and chemical characteristics were evaluated: a biomass-derived carbon (ACS) and commercial carbon (ACC). The ACC support exhibited a higher density of thermally stable oxygen-containing functional groups, which promoted stronger metal-support interactions and an increased proportion of surface reduced Cu species (Cu⁰/Cu⁺), resulting in superior catalytic performance compared to ACS. Based on these results, the effect of Cu loading (5–20 wt.%) was further studied on the ACC support. The catalysts were characterized by N₂ physisorption, XRD, TEM, H₂-TPR, He-TPD, NH₃-TPD, and XPS. Increasing Cu loading enhanced the amount and reducibility of Cu species; however, excessive loading led to particle growth, pore blockage, and reduced metal dispersion. Catalytic activity exhibited volcano-type behavior, reaching a maximum at 15 wt.% Cu, where an optimal balance between reduced availability of Cu species and metal-support interaction was achieved. Selectivity toward furfuryl alcohol remained essentially unchanged across all catalysts, indicating that the catalytic performance is closely related to the surface chemistry and relative concentration of reduced Cu sites and is not significantly affected by acidity. These results highlight the critical role of support properties and metal loading in controlling catalyst performance, providing insights for the rational design of efficient Cu-based catalysts for biomass valorization. Full article

The rational design of metal-free catalysts capable of efficiently converting CO₂ under atmospheric pressure remains a significant challenge in sustainable chemistry. Herein, we report a series of clamp-shaped dihydrogen-bonded iodide catalysts (CDBI catalysts) featuring a preorganized bifunctional framework that integrates dual hydrogen-bond donors and an intrinsic iodide nucleophile within a single molecular scaffold. Systematic structural variation revealed that catalytic activity is highly sensitive to electronic modulation, steric accessibility, and precise spatial arrangement between the hydrogen-bonding units and the iodide center. The optimal catalyst enabled solvent-free cycloaddition of CO₂ with epoxides at 1 atm CO₂, affording up to 99% conversion and >99% selectivity at 80 °C within 12 h. Substrate scope studies demonstrated efficient transformation of a wide range of terminal epoxides, while sterically demanding substrates exhibited reduced reactivity consistent with a confined activation mode. Mechanistic investigations support a cooperative pathway in which dual hydrogen-bond activation and proximal halide nucleophilicity operate synergistically within a preorganized clamp-shaped pocket. Comparative analysis with representative catalytic systems highlights the ability of this metal-free design to achieve high efficiency under atmospheric CO₂ without cocatalysts or solvents. These findings demonstrate that structural preorganization represents an effective strategy for promoting sustainable CO₂ utilization under operationally simple conditions. Full article

The design and manufacture of bifunctional electrocatalysts are of great significance in the electrolysis of water. Herein, porous organic polymers (POPs) of metal–N-heterocyclic carbene were synthesized from imidazolium borate ionic POPs and supported on a nickel foam surface (Pd–NHC/NF, Ag–NHC/NF, and Cu–NHC/NF). Among them, Pd–NHC/NF exhibited high activity for both hydrogen evolution reaction and oxygen evolution reaction. The oxygen evolution overpotential of Pd–NHC/NF was 245 mV with a Tafel slope of 83 mV dec⁻¹; the hydrogen evolution overpotential was 139 mV with a Tafel slope of 94 mV dec⁻¹ at 10 mA cm⁻² in alkaline media. Additionally, the assembled Pd–NHC/NF||Pd–NHC/NF electrolyzer demonstrated excellent performance in electrocatalytic water-splitting, achieving a voltage of 1.55 V at 10 mA cm⁻² and showing outstanding stability for over 90 h in the long-term test. The results highlighted the substantial capability of Pd–NHC as a bifunctional catalyst for electrocatalytic water-splitting. Full article

Demand for greener and safer chemistries has driven the innovation of bioinspired and enzyme-mimicking catalysts for selective and efficient oxidation and hydrogenation under mild conditions. Natural catalysts, including peroxidases, oxidases, hydrogenases, oxygenases and dehydrogenases, boast remarkable activity, specificity, stability, selectivity, low energy requirements and atom economy. Disadvantages of enzymes, such as poor thermal stability, a narrow operational range, low recovery yield and the expense of purification, are motivating the discovery and design of enzyme substitutes. Several artificial platforms have appeared recently: nanozymes, artificial metalloenzymes, biomimetic metal Complexes, MOFs, atomic catalysts, bioinorganic hybrid systems, among others. These systems aim to replicate key structural and mechanistic features of enzymes while providing greater operational stability, recyclability, and scalability. Recent work has demonstrated the benefit of enzyme mimics in increasing eco-sustainability in reactions such as alcohol oxidation, selective alkane oxidation, waste degradation, catalytic photooxygen activation and biomass waste conversion. Similarly, biomimetic hydrogenation catalysts have shown outstanding activity in asymmetrically hydrogenating chemicals, reducing CO₂ into chemicals, hydrogenation by hydrogen transfer and creating hydrogen through water. Through control of active sites, second coordination sites, defects and electrons/protons in the system, significant gains have been seen in reaction selectivity and frequency of turning over substrate into product. Nanozymes, biohybrid catalysis and artificial catalysts guided by deep learning are further broadening the applications of biomimetic catalysis in oxidation and hydrogenation. The article review aims to provide a summary of the most current progress with bioinspired and enzyme-mimicking catalysts, focusing on catalytic mechanisms, how to design such catalysts, how green chemistry benefits from their development and where further application is likely in the coming years. Full article

Glycolysis of poly(ethylene terephthalate) (PET) offers a promising route for chemical recycling, yet conventional homogeneous catalysts often suffer from low selectivity, severe side reactions (especially diethylene glycol, DEG formation), and detrimental metal residues that compromise the quality of recycled products. To address these challenges, we herein develop dipotassium phenylphosphonate (PPOA-K) as an efficient homogeneous catalyst for PET glycolysis. Under optimized conditions (1 wt% catalyst, 197 °C, EG/PET mass ratio 3:1, 90 min, atmospheric pressure), PPOA-K achieves 100% PET depolymerization and a high BHET yield of 86.0%, and the reaction follows apparent first-order kinetics with an activation energy of 70.3 kJ·mol⁻¹. Beyond its high catalytic activity, PPOA-K effectively suppresses the acid-catalyzed etherification of ethylene glycol to DEG, a common side reaction that reduces monomer purity and degrades recycled polyester properties. Remarkably, the trace amount of PPOA-K remaining in the recovered BHET (17.3 ppm) is not detrimental; instead, it continues to inhibit DEG formation during repolymerization and acts as a thermal stabilizer, improving the melting point and thermal stability of recycled PET. The advantages of PPOA-K are further demonstrated in a partial (in situ) glycolysis–repolymerization process, where it reduces the DEG content in the final rPET to 1.78% (vs. 2.25% for conventional Zn(OAc)₂), yielding rPET with a higher melting point, higher crystallinity, and better color. This work demonstrates that dipotassium phenylphosphonate uniquely combines high catalytic activity, side reaction suppression, and beneficial residue effects, offering a new catalyst design strategy for high-quality PET recycling. Full article

Ammonia decomposition over non-precious metal thermos-catalysts offers a viable and cost-effective pathway for sustainable hydrogen production. In this study, LaCeO₃ perovskite was synthesized using a citric acid complexation method and employed as a support for mono- and bimetallic catalysts prepared by incipient wetness impregnation, maintaining a total metal loading of 10 wt%. Structural and surface properties were systematically investigated using BET, XRD, H₂-TPR, SEM, TEM, and CO₂-TPD. Among the monometallic catalysts (Ni, Co, and Fe), 10%Ni/LaCeO₃ exhibited the highest activity, which is attributed to its enhanced reducibility and optimal surface basicity, facilitating NH₃ activation. Bimetallic systems (Ni-Co, Ni-Fe, and Co-Fe) with equal metal loadings (5 wt% each) showed better activity compared to their monometallic counterparts following the order: 5%Ni–5%Co/LaCeO₃ > 5%Ni–5%Fe/LaCeO₃ > 5%Co–5%Fe/LaCeO₃. The improved performance of the Ni-Co system is due to structural interactions between Ni and Co, which promote hydrogen desorption and accelerate N–H bond cleavage, while suppressing nitrogen recombination as the rate-limiting step. Further systematic optimization of the Ni/Co ratio showed that 8%Ni–2%Co/LaCeO₃ had the highest catalytic activity with consistent performance over 50 h. This optimal composition provides a balanced distribution of active metallic sites and moderate-to-strong basic sites, enhancing NH₃ adsorption and intermediate transformation. These findings show that LaCeO₃-supported Ni-Co catalysts are promising candidates for efficient hydrogen production from ammonia without using noble metals. Full article

The discharge of pesticide residues (PRs) from agricultural activities into water bodies has raised concerns about their toxicity to humans and the ecosystem. Traditional methods such as adsorption, membrane filtration, biological treatment, and conventional filtration usually result in incomplete removal of PRs. Currently, removal of PRs using advanced oxidation processes, particularly metal oxide-based photocatalysts, is considered a promising way. This review provides a comprehensive overview of recent advances in the photocatalytic degradation of PRs using TiO₂-based photocatalysts (T-BPs), the most widely investigated metal-oxide photocatalyst systems. First, we discuss the distribution, types, and negative impacts of major PRs on humans and the ecosystem. Next, we explore modification methods to enhance the properties of T-BPs, including light absorption behavior, charge separation rate, and photocatalytic degradation performance toward PRs. Afterward, this review carefully examines current challenges, such as complex water matrices, T-BP stability, energy supply for photocatalysis, and toxicity reduction. Finally, we highlight key future research directions, like the development of visible light-driven photocatalysts, enhanced mineralization efficiency, reduced secondary environmental risks, and the design of highly reliable catalyst and reactor systems for sustainable large-scale applications. Full article