Search Results (1,026)

There is increasing interest in structured layered double hydroxide (LDH)-based catalysts because they combine tunable acid–base/redox chemistry with reactor architectures that can reduce diffusion lengths, improve heat management, and lower pressure-drop penalties. This review evaluates LDH, LDH-derived oxide (LDO/MMO), reduced metal/LDO, reconstructed hydroxide-rich, and mixed dynamic states integrated into honeycomb monoliths, open-cell foams, meshes/felts, thin films, washcoats, coated plates, microchannels, capillaries, and additively manufactured lattices. To move beyond descriptive comparison, the literature is assessed using unified evaluation dimensions: operative active state, support architecture, coating/integration route, active-phase loading, coating thickness and uniformity, reactor-volume-normalized productivity or STY, ΔP/L, axial/radial thermal gradients, time-on-stream, coating loss, regeneration recovery, and pilot-readiness. Representative benchmarks illustrate both the promise and reporting gaps of the field: NiFe-LDH-derived monoliths for CO₂ methanation have reached ~70% CO₂ conversion at 300 °C with >90% CH₄ selectivity and only 0.7% post-test mass loss; NiFe-LDH/iron-foam monoliths retained 85% ozone conversion after 168 h; high-entropy LDH-derived oxides showed T50/T90 values of 246/254 °C for toluene oxidation; and Au/LDH capillary films achieved 31.9% glycerol carbonate yield and 3.78 g h⁻¹ g⁻¹ productivity. The strongest current cases are pollution abatement and CO₂ methanation, whereas biomass upgrading, fine-chemical flow, high-entropy coatings, and photo/electrocatalytic films require deeper module-level validation. Overall, structured LDH catalysts should be treated as coupled chemistry–coating–reactor systems whose performance must be judged simultaneously by activity, accessible catalyst inventory, transport efficiency, pressure drop, thermal profile, durability, regeneration, and manufacturability. Full article

Seawater zinc–air batteries (SZABs) stand out as promising candidates for marine and offshore energy supply. However, their practical implementation is greatly restricted by tardy oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics at the air cathode, severe chloride ion-induced catalyst corrosion, and structural deterioration of traditional binder-containing electrodes in seawater media. Herein, we design and fabricate a binder-free integrated electrode consisting of carbon-supported iron phthalocyanine- modified star-like cobalt sulfide arrays directly grown on nickel foam. The optimal catalyst (0.3FePc-C/CoS) integrates the respective advantages of Fe single atoms and cobalt sulfide, exhibiting excellent ORR and OER activity, delivering a prominent half-wave potential of 0.89 V versus RHE, and exhibiting a low OER overpotential of 160 mV at 50 mA cm⁻² and robust stability in seawater. As a self-supported air cathode, the 0.3FePc-C/CoS-based battery attains a favorable open-circuit voltage reaching 1.48 V, prominent peak power density (126.4 mW cm⁻²), small charge–discharge potential polarization (0.52 V), excellent energy efficiency (68.8%) and extraordinary long-term cycling durability (>360 h). This work not only discloses a feasible synergistic modulation strategy for constructing high-performance bifunctional electrocatalysts but also provides a valuable reference for developing corrosion-resistant integrated air electrodes toward practical marine energy storage applications. Full article

The purpose of this study was to investigate the effectiveness and mechanism of iron-based catalysts in the treatment of phenolic wastewater by catalyzing ozone oxidation. The removal rates of phenolics and COD were systematically examined using simulation experiments with water and actual wastewater, which involved analyzing the effects of reaction time, pH, ozone dosage, catalyst dosage, and initial concentration. The phenol and COD removal rates in the simulated wastewater were 95.9% and 93.5%, respectively, respectively, while the ozone dosage was 16 mg/L/min, pH was 6.7–6.8, and catalyst dosage was 0.3 g/L. The phenol and COD removal rates in the actual wastewater were 68.6% and 68.0%, respectively. The reaction time was 30 min. The system’s efficient removal ability for phenolic compounds, polycyclic aromatic hydrocarbons, and others was confirmed through three-dimensional fluorescence and ultraviolet spectroscopy. The iron-based catalyst generates ·OH through three pathways: adsorption of activated ozone on surface active sites, continuous production of free radicals by Fe²⁺/Fe³⁺ cycling, and direct activation of ozone by Fe²⁺. This mechanism analysis showed that the catalyst generates ·OH. These pathways convert pollutants into small molecules or mineralized by attacking the aromatic rings and conjugated structures of pollutants. Technical references for the deep treatment of phenol-containing wastewater are provided in this study. Full article

The catalytic removal of refractory VOCs in gas–solid reactions usually suffers from the formation of toxic byproducts and catalyst deactivation. The advanced oxidation process (AOP) wet scrubber has recently attracted interest in VOCs purification due to its high efficiency and inhibited gaseous byproducts emission. MOFs/metal sulfides (termed M50C50) were designed to activate peroxymonosulfate (PMS) for toluene removal in a wet scrubber. The heterojunction interface synergistically couples MIL-100(Fe) and CoS for dual functions, the M50C50 enabled the rapid transfer the toluene from the gas phase to the aqueous phase, where they were subsequently mineralized by SO₄^•− and •OH radicals. The primary active sites responsible for PMS activation were identified as reducing sulfur species, along with low-valence cobalt and iron species. Over 90% of toluene were removed with a wide pH range, while •OH and SO₄^•− were involved in the mineralization of intermediates. The process showed high mineralization efficiency (75% CO₂ evolution) and effectively reduced the formation of toxic byproducts, underscoring its potential for minimizing secondary pollution risks. This work provides a novel route to designing composite catalysts for deep VOC oxidation via AOP wet scrubbers, greatly facilitating their use in environmental remediation. Full article

Carbamazepine (CBZ), a poorly biodegradable antibiotic, is widely detected in aquatic environments, posing potential threats to ecosystems and human health. There is an urgent need to develop efficient water treatment technologies. This study successfully prepared nitrogen-doped biochar composite materials loaded with zero-valent iron (Fe⁰@CN) via a one-pot calcination method for activating peroxymonosulfate (PMS) to degrade CBZ. The material was systematically characterized using multiple analytical techniques. Results indicate that Fe⁰@CN-1.5 exhibits a high specific surface area (482.65 m²/g) and an abundant mesoporous structure, with nitrogen doping promoting graphitic structure formation and the uniform dispersion of zero-valent iron. Under conditions of a 0.3 g/L catalyst loading, a 15 mM PMS concentration, and an initial pH of 5.5, 30 mg/L of CBZ achieved 97% degradation within 30 min. Radical quenching experiments and electrochemical analysis indicate that ·SO₄⁻ and ·OH are the primary active species in this system, alongside non-radical electron transfer processes. The material demonstrates excellent degradation performance and cycling stability across various real-world water bodies and pollutant systems. This study provides a carbon-based catalytic material with application potential and a theoretical basis for the efficient treatment of antibiotic wastewater. Full article

Beauty salon wastewater is an emerging commercial greywater characterized by high chemical oxygen demand (COD), intense color, and low biodegradability due to the presence of surfactants and oxidative dye precursors. This study evaluated a solar-assisted photo-Fenton process using waste-derived iron sludge as a heterogeneous catalyst for treating real beauty salon effluent. Operational parameters, including pH, H₂O₂ concentration, iron sludge dosage, reaction time, and temperature, were optimized based on dye removal and COD reduction. Under optimal conditions (pH = 3, H₂O₂ = 400 mg L⁻¹, iron sludge = 40 mg L⁻¹), the system achieved approximately 98% dye removal and 95% COD reduction within 50 min of irradiation. Additionally, maximum performance was observed at 40 °C, while higher temperatures reduced efficiency due to non-productive H₂O₂ decomposition. Kinetic analysis was performed, and the results indicated predominant second-order behavior. Thermodynamic evaluation confirmed an endothermic process with moderate activation energy (Eₐ = 21.8 kJ mol⁻¹). Response surface methodology confirmed strong parameter interactions and high predictive accuracy. The integration of solar irradiation with iron sludge valorization provides a sustainable and decentralized solution for treating dye-loaded beauty salon wastewater. Full article

Achieving efficient overall water splitting with non-precious metal catalysts remains a significant challenge due to the sluggish kinetics of both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, we report a nickel–iron bimetallic doped geopolymer electrocatalyst (Ni_0.9Fe_0.1-GP) fabricated via a one-step alkali activation method on 316L stainless steel. Structural characterizations reveal that Fe³⁺ incorporation alters the distribution of Na⁺ and Ni²⁺ within the geopolymer network and modulates the Ni electronic structure. Electrochemical measurements show that Ni_0.9Fe_0.1-GP delivers an HER overpotential of 332.42 mV and an OER overpotential of 227.31 mV at 10 mA cm⁻², outperforming Ni-GP and bare 316L SS. The practical operating voltage of Ni_0.9Fe_0.1-GP is 1.81 V, while the two-electrode electrolyzer delivers a comparable current density at 1.90 V (after accounting for uncompensated system resistances). Long-term stability tests demonstrate the superior durability of Ni_0.9Fe_0.1-GP during HER, OER, and overall water splitting. Mechanistic studies reveal the dual role of Fe³⁺: substantially increasing the electrochemical active surface area (ECSA) while modulating the Ni electronic structure, and improving structural stability through strong chemical anchoring within the geopolymer network. This work provides new insights into cost-effective bifunctional electrocatalysts and expands the application of geopolymers as functional catalytic supports for water splitting. Full article

A facile co-precipitation method was employed to synthesize copper(II) ferrite composites with carbon materials (reduced graphene oxide, graphitic carbon nitride, and their mixture), followed by heat treatment at 700 °C. To obtain Fe-Cu-containing catalysts, copper ferrite composites were electrochemically reduced. Structures, compositions, and morphologies of the composites were studied using scanning electron microscopy, X-ray diffraction techniques, and thermogravimetric analysis. The results showed that graphitic carbon nitride had the strongest effect on the phase composition of copper ferrite. Crystalline phases of reduced copper and iron metals appear in the CuFe₂O₄/g-C₃N₄ composite during the annealing process, facilitating further complete electrochemical reduction of copper ferrite and shortening its duration. The resulting Fe-Cu/C composites were used as catalysts in the electrohydrogenation of acetophenone as a model compound. The activation of the cathode with Fe-Cu/C catalysts increases the rate of acetophenone hydrogenation and leads to the selective formation of a single product, 1-phenylethanol, in high yields. Full article

The present study investigates the solar-assisted photo-Fenton-like degradation of a reactive azo dye (Red SPR) using an iron-based metal–organic framework, MIL-100(Fe), as a heterogeneous catalyst. The synthesized MIL-100(Fe) was successfully characterized by XRD, SEM, EDX, and FTIR analyses, confirming the formation of a crystalline, porous structure with well-dispersed Fe active sites. The catalytic performance was systematically evaluated under various operational parameters, including hydrogen peroxide dosage, catalyst loading, pH, circulation flow rate, initial dye concentration, and temperature. The results demonstrated that optimal degradation efficiency was achieved at pH 3.0, H₂O₂ concentration of 400 mg L⁻¹, and catalyst dosage of 40 mg L⁻¹, while a circulation flow rate of 400 mL min⁻¹ ensured optimal hydrodynamic conditions. The system exhibited rapid degradation kinetics, achieving nearly complete dye removal within 60 min under solar irradiation. Kinetic analysis revealed that the degradation process follows pseudo-first-order behavior, with rate constants increasing from 0.1040 to 0.1589 min⁻¹ as temperature increased from 25 to 55 °C. Thermodynamic analysis indicated that the process is endothermic (ΔH` = 8.72 kJ mol⁻¹) and kinetically favorable with a low activation energy (Ea = 11.32 kJ mol⁻¹), while negative entropy values suggested the formation of an ordered transition state. Radical scavenger experiments confirmed that hydroxyl radicals (•OH) are the dominant reactive species, with secondary contributions from superoxide radicals (O₂•⁻). The enhanced performance is attributed to the synergistic effect of solar irradiation and Fe³⁺/Fe²⁺ redox cycling within the MIL-100(Fe) framework. Hence, the study demonstrates that MIL-100(Fe) is a highly efficient and sustainable catalyst for solar-driven wastewater treatment applications. Full article

This study explores the potential of utilizing biogenic manganese oxides (BMOs) produced by Mn-oxidizing Pseudomonas putida MnB1 to facilitate metal cation uptake for rare earth element (REE) sequestration and the synthesis of novel materials. Previous studies have shown that P. putida MnB1 efficiently oxidizes environmental Mn(II) to Mn(IV)-oxides, producing BMOs with unique physicochemical properties. Unlike their abiotic counterparts, BMOs exhibit high surface area, reactivity, and amorphous, poorly crystalline structures, making them promising platforms for adsorbing metal cations. This research study, building on the prior work, demonstrates the incorporation of ten different main group, transition, and rare earth metals into the BMO material, with structural characterization conducted via scanning electron microscopy and powder X-ray diffraction. Compositional characterization was determined by inductively coupled plasma optical emission spectroscopy and energy dispersive X-ray spectroscopy via scanning electron microscopy. Following the initial screening of these ten cations, batch adsorption studies were performed for a representative light REE, heavy REE, and transition metal-spiked sample prepared with real wastewater effluent indicating that the BMO material in this study is promising for sequestering REEs from real water streams. These findings advance the understanding of biologically mediated metal adsorption and open pathways for designing new functional materials with potential applications in rare earth sequestration and catalysis. To highlight this later point, the BMO materials with an incorporated main group (Al³⁺, Ca²⁺) or transition metal cation (Fe³⁺, Cu²⁺) were tested electrochemically for their ability to act as water oxidation catalysts, and each of these materials’ activity was comparable to BMO except for the material with incorporated iron, which showed significantly enhanced activity. Full article

The massive discharge of methylene blue causes severe water pollution, and the development of efficient and stable heterogeneous Fenton catalysts is crucial for wastewater treatment. To address the shortcomings of traditional iron-based amorphous catalysts, such as low activity and poor stability, this study employed Fe₈₀Si₆B₁₀Cu₁Nb₃ five-component amorphous alloy as the catalyst to investigate its catalytic degradation performance, cyclic stability, and catalytic mechanism for MB. Batch experiments, SEM, XRD characterization, and kinetic fitting were combined to carry out the research. The results showed that under the optimal conditions (25 °C, pH = 3, H₂O₂ concentration of 5 mM, catalyst dosage of 0.5 g/L), the catalyst could completely degrade methylene blue within 9 min with a reaction rate constant k_obs of 0.44 min⁻¹, and the degradation efficiency showed no obvious attenuation after 20 consecutive cyclic degradation runs. After degradation, slight selective corrosion occurred on the catalyst surface, while the amorphous structure of the matrix remained stable. This study confirms that the Cu/Nb dual synergy improves the catalytic performance and stability, clarifies the relevant catalytic mechanism, and provides theoretical and technical support for the design of high-performance iron-based amorphous catalysts and the treatment of dye-containing wastewater. Full article

Direct Coal Liquefaction (DCL) is a promising route for converting abundant coal resources into liquid fuels, yet its efficiency remains strongly dependent on catalyst performance. In this work, we present an integrated computational framework combining density functional theory (DFT) calculations with machine learning (ML) to investigate iron–sulfur (FeS) cluster catalysts for DCL. DFT calculations were employed to examine hydrogen-donor dissociation and coal-derived radical hydrogenation on representative FeS clusters. The results indicate that the most favorable catalytic pathways arise from the cooperation between metallic Fe sites (Fe_2) and interfacial Fe sites adjacent to sulfur (Fe_1), while sulfur atoms mainly play an indirect structural and electronic modulation role. Based on these mechanistic insights, a database containing thermodynamic and kinetic data for 636 reactions across 50 FeS cluster models was constructed. This dataset was then used to train three ML classifiers, among which the Random Forest model showed the best performance, reaching accuracies of 80% for H-donor cleavage and 93% for radical hydrogenation on the held-out test sets. SHapley Additive exPlanations (SHAP) analysis further showed that descriptors associated with Fe active-site identity were among the most influential variables in both tasks. Overall, this work provides a mechanistically informed and interpretable computational framework for understanding FeS-catalyzed DCL chemistry and for the preliminary screening of catalyst motifs within the chemical space covered by the present FeS cluster library. Full article

Electrochemical water splitting for hydrogen production is a key technological route toward the large-scale generation of green hydrogen. However, the anodic oxygen evolution reaction (OER) suffers from sluggish kinetics and high overpotential, necessitating the development of non-noble metal catalysts that simultaneously possess low cost, high activity, and excellent stability. In this work, a nitrogen-doped graphene quantum dots@nickel–iron layered double hydroxide (N-GQDs@NiFe-LDH) composite catalyst was in situ constructed via a facile hydrothermal strategy. Benefiting from the electronic modulation and structural confinement effects of N-GQDs, the intrinsic catalytic activity and structural stability of the catalyst were simultaneously enhanced. The as-prepared catalyst requires an overpotential of only 320 mV to deliver a current density of 500 mA cm⁻² and maintains 98% of its initial activity after 100 h of chronoamperometric stability testing, demonstrating promising potential for practical applications. Multiscale characterizations revealed that N-GQDs formed strong electronic interactions with Ni/Fe active sites at the interface, significantly enhanced interfacial electron transport, and accelerated the OER kinetics. This study demonstrates that the N-GQDs@NiFe-LDH catalytic system constructed via an interfacial heterostructure engineering strategy provides a new insight for the rational design and development of efficient non-noble-metal OER electrocatalysts. Full article

Ciprofloxacin (CIP) is a persistent fluoroquinolone antibiotic frequently detected in water bodies, and its efficient mineralization remains a challenge in wastewater treatment. In this work, iron oxide–chitosan macroporous nanocomposite hydrogels were developed as heterogeneous catalysts for the electro-Fenton degradation of CIP. The materials were synthesized via Pickering high internal phase emulsion templating, yielding monoliths with a three-dimensional interconnected porous structure, an average pore size of 18.9 ± 0.7 µm, a window size of 8.1 ± 0.7 µm, an openness degree of 39.6%, a specific surface area of 1.77 m² g⁻¹, an iron content of 64.2 mg g⁻¹, and a crosslinking degree of 92.1%. The monoliths exhibited controlled swelling in aqueous medium at pH 3, with a gravimetric water uptake of 142.1 ± 2.3% and a volumetric swelling of 39.3 ± 1.2% at equilibrium. Iron oxide particles remained exposed on the porous surface, providing accessible catalytic sites, while the interconnected porosity favored reactant diffusion. Compared with direct anodic oxidation, which achieved 32% total organic carbon removal after 20 min, the heterogeneous electro-Fenton process using the synthesized monoliths as catalysts showed superior performance, reaching nearly 95% removal within 2 min and complete mineralization within 15 min. This enhanced performance was associated with higher hydroxyl radical generation (~3.5 µM) than that observed for anodic oxidation alone (~1.5 µM). These findings highlight the potential of biodegradable iron oxide–chitosan macroporous hydrogels as sustainable catalysts for antibiotic removal from water. Full article

The Fenton reaction remains one of the most widely investigated advanced oxidation processes for wastewater treatment due to its ability to generate highly reactive oxygen species capable of degrading persistent organic pollutants. However, classical homogeneous Fenton systems suffer from significant limitations, including narrow pH applicability, iron sludge generation, and poor catalyst reusability. In response, extensive research has focused on the development of heterogeneous and advanced Fenton-like catalysts aimed at overcoming these challenges while enhancing catalytic efficiency and operational stability. This review provides a comprehensive and critical analysis of the evolution of Fenton catalysis, from classical homogeneous systems to advanced materials, including nanostructured catalysts, carbon-based Fe–N–C systems, metal–organic frameworks, and single-atom catalysts. A unified evaluation framework is proposed, integrating key performance parameters such as catalytic activity, manufacturability, stability, and catalyst lifespan. Comparative analysis reveals that improvements in activity are often accompanied by trade-offs in cost and scalability, indicating that the most advanced materials do not necessarily provide the best practical performance. A life cycle-oriented perspective is incorporated, emphasizing catalyst reuse, lifespan, and iron leaching, and providing quantitative insight into cumulative catalytic performance. The results demonstrate that long-term efficiency is governed not only by intrinsic activity but also by durability and operational stability under realistic conditions. Finally, current challenges and future directions are discussed, including scalable synthesis, improved mechanistic understanding, and integration into hybrid treatment systems. This review bridges the gap between fundamental research and practical application by highlighting the importance of balancing performance, stability, and sustainability in the design of next-generation Fenton catalysts. Full article