Search Results (1,932)

:Hierarchical porous catalysts now benefit from intentional co-design of transport pathways and catalytic functionality. This review critically examines intelligent micro–mesoporous nanoarchitectures, emphasizing pore connectivity and active-site cooperativity as inseparable design principles. We first outline limitations of purely microporous systems (diffusion constraints, site inaccessibility, deactivation) and then show how multi-scale networks overcome these issues. Engineering strategies for pore connectivity involving bottom-up templating, post-synthetic reconstruction, top-down desilication/dealumination are systematically reviewed alongside metrics (tortuosity, connectivity, accessibility). Active-site cooperativity is examined via acid-based bifunctionality, metal-acid coupling, single-atom catalysis and compartmentalized architectures for cascade reactions. The central thesis is that optimal performance emerges when transport and catalytic site engineering are coupled, supported by evidence from zeolites, metal–organic frameworks, silica nanoreactors, heteroatom-doped carbons and advanced electrocatalysts. Applications include biomass upgrading, selective oxidation, and energy conversion. The review also covers stability, deactivation, and regeneration, suggests standardized reporting criteria, and highlights future challenges such as using AI for catalyst design, operando transport mapping, scalable catalyst synthesis, and programmable catalytic nanoarchitectures. This review offers a predictive design strategy for next-generation multifunctional catalytic materials by focusing on the integrated transport-reaction system instead of only focusing on the structure. Full article

Heterojunction construction is a key strategy for enhancing the photocatalytic efficiency of semiconductors. In this study, a composite of sulfur-doped CoAl layered double hydroxide and Fe-doped C₃N₅(S-CoAl-LDH/Fe-C₃N₅) was developed via a hydrothermal method for the synergistic oxidation-reduction degradation of the organic pollutant tetracycline (TC) and the detoxification of heavy-metal ions (Cr(VI)) in wastewater. After optimization, the CAF-4 heterojunction (the composite with 20 wt% Fe-C₃N₅ loading) exhibited TC degradation rates 5.51 and 3.97 times higher than those of pristine Fe-C₃N₅ and S-CoAl-LDH, respectively; under simulated sunlight, the Cr(VI) reduction rates were 11.75 and 4.22 times higher, respectively. The as-prepared catalyst demonstrated good stability across a wide pH range, in the presence of various cations and anions, and in different water matrices. Under coexisting pollutant conditions, the composite still achieved removal efficiencies of 82.1% for Cr(VI) and 64.7% for TC. After five cycling runs, the adsorption-photocatalytic efficiency of the composite for the removal of Cr(VI) and TC composite pollutants remained above 80%. Overall, CAF-4 shows great promise for application in the adsorption-photocatalytic treatment of wastewater containing combined Cr(VI) and TC pollution. Full article

The copper ferrite/nitrogen-doped biochar (CuFe₂O₄/N_x-BC) was synthesized by a one-step sol–gel pyrolysis method, and its efficiency in activating PS to degrade MB was evaluated. The influences of preparation conditions, degradation conditions, and common anions on the degradation efficiency of MB were investigated, and the mechanism of CuFe₂O₄/N_0.5-BC activating PS was inferred. The results showed the saturation magnetization of CuFe₂O₄/N_0.5-BC was 25.53 emu/g. Under the optimal degradation conditions, compared to PS alone, the degradation efficiency of MB in the CuFe₂O₄/N_0.5-BC + PS system increased from 26.2% to 94.1%, the reaction rate constant in the CuFe₂O₄/N_0.5-BC + PS system (0.02954 min⁻¹) was 9.12 times higher than that in the PS alone system (0.00324 min⁻¹); Compared to the CuFe₂O₄/BC system, the degradation efficiency of MB in the CuFe₂O₄/N_0.5-BC + PS system increased from 34% to 94.1%, while the reaction rate constant is 1.1 times that in the CuFe₂O₄/BC + PS system. After CuFe₂O₄/N_0.5-BC underwent five cycles of application, the degradation efficiency of MB in the CuFe₂O₄/N_0.5-BC + PS still reached 87.5%. SO₄^•− plays a major role, •OH played a certain role and O₂^•− was also responsible for the degradation of MB in the CuFe₂O₄/N_0.5-BC + PS system. CuFe₂O₄/N_0.5-BC is a green and effective catalyst for the PS-AOP method to treat MB-contaminated water. Full article

Zeolitic imidazolate framework-8 (ZIF-8) has emerged as a material for electrochemical energy conversion, serving dual primary roles in fuel cell technologies: (i) as an electrocatalyst precursor for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) through pyrolysis-derived N-doped porous carbons and metal–nitrogen–carbon (M–N–C) structures, and (ii) as a membrane component that enhances proton conductivity via imidazole-mediated Grotthuss hopping while suppressing fuel crossover through molecular sieving. This comprehensive review systematically evaluates ZIF-8 performance across multiple fuel cell types, including primarily proton exchange membrane fuel cells (PEMFCs), as well as direct methanol fuel cells (DMFCs), anion exchange membrane fuel cells (AEMFCs), and microbial fuel cells (MFCs), while also covering related electrochemical applications such as zinc–air batteries, supercapacitors, and water splitting devices, where ZIF-8-derived materials demonstrate improved catalytic activity. The review examines structure–performance relationships, highlighting strategies such as heteroatom doping, bimetallic synergy, hierarchical porosity engineering, and polymer composite fabrication that have enabled ZIF-8-based catalysts to achieve ORR half-wave potentials and PEMFC power densities, rivaling commercial Pt/C systems. ZIF-8 composite membranes demonstrate proton conductivities in polybenzimidazole systems and effective methanol blocking. Despite improved progress, challenges persist regarding long-term stability, scalable synthesis, and degradation mechanism understanding. This review critically analyzes recent advances, identifies performance-limiting factors across applications, and outlines future research directions for developing commercially viable ZIF-8-based electrochemical technologies. Full article

In this study, nine barium sulfate (BaSO₄)-supported heterogeneous catalysts (C1–C9) were synthesized via three modification strategies: stearic acid coating (C1–C3), physical doping (C4, C6, and C8), and sol-gel processing with calcination (C5, C7, and C9). Their comprehensive characterization revealed that sol-gel-synthesized C7 exhibited the most favorable surface properties, including well-dispersed Al–O–Si species, tetrahedrally coordinated Al³⁺, and abundant Brønsted acid sites. Their catalytic performance was evaluated in the chlorination of toluene, fluorobenzene, bromobenzene, and iodobenzene, using hydrochloric acid (HCl) as the chlorine source and either hydrogen peroxide (H₂O₂) or ammonium persulfate ((NH₄)₂S₂O₈) as the oxidant. C7 achieved complete toluene conversion (100%) at 60 °C under optimized conditions and exhibited high conversions of fluorobenzene (55%), bromobenzene (76%), and iodobenzene (46%). Notably, ammonium persulfate enabled a unique in situ halogen exchange pathway, yielding chlorobenzene as the exclusive product from bromobenzene and iodobenzene. XRD and XPS analysis of crystalline by-products confirmed the formation of NH₄HSO₄, BaSO₄, and NH₄Cl, providing evidence for the persulfate-driven radical mechanism. Iodine detection in upper-layer crystals confirmed iodobenzene products, while the absence of chlorine signals in the upper layer confirmed separation of organic and inorganic species. The detection of barium sulfate peaks confirms that the catalyst support retains its structural integrity under harsh reaction conditions, demonstrating chemical stability and reusability potential. Collectively, these findings establish a clear structure–activity relationship and demonstrate that the synergy between modified BaSO₄ surfaces and persulfate-generated radicals provides an efficient, sustainable platform for aromatic chlorination, offering significant potential for pharmaceutical, agrochemical, and fine chemical manufacturing applications. Full article

Carbon-based materials are widely employed in electrocatalytic energy conversion and storage technologies owing to their high electrical conductivity, chemical stability, tunable structure, and low cost. However, the limited intrinsic activity and surface inertness of pristine carbon materials often necessitate surface modification to generate catalytically active sites and improve interactions with reactants and electrolytes. Among the available approaches, plasma functionalization has emerged as a versatile, rapid, solvent-free, and potentially resource-efficient technique that enables systematic tuning of surface chemistry while often limiting modification primarily to the near-surface region. This review discusses the fundamentals of plasma-assisted surface modification of carbon materials, including plasma generation, reactive species, plasma–surface interaction mechanisms, and the influence of key processing parameters such as gas composition, power, pressure, and treatment time. Particular attention is devoted to plasma-induced heteroatom doping, defect engineering, surface functionalization, and the dynamic structural evolution of carbon frameworks during treatment. The impact of these modifications on the physicochemical properties and electrocatalytic performance of carbon materials is critically examined with respect to representative reactions, including the oxygen reduction, oxygen evolution, and hydrogen evolution reactions. The advantages, limitations, and scalability of plasma technologies are also discussed, along with current challenges in process control and reproducibility. Finally, future opportunities involving operando diagnostics, single-atom catalysts, advanced porous carbon architectures, and industrial-scale plasma processing are highlighted. Plasma processing offers a versatile route to carbon surface and catalyst-interface engineering, although standardized reporting and quantitative plasma–structure–performance relationships are still required for rational process design and scale-up. Full article

The catalytic performance of copper-modified strontium titanate-based materials (SrTi_1−xCu_xO₃, where x = 0.02, 0.04, 0.06, and 0.10) in the NH₃-SCR and NH₃-SCO processes was studied. The catalytic materials were obtained by the modified Pechini method and characterized in terms of structural properties (XRD, XAS), surface composition (XPS), microstructural properties (SEM/EDS, SSA measurements), and reducibility (TPR). Catalytic activity, selectivity to N_2, and long-term stability in the NH₃-SCR and NH₃-SCO processes were experimentally verified. The catalytic materials consisted of agglomerates of nanocrystalline perovskite grains with homogeneously distributed copper, except for the material with the highest copper content. The catalytic activity of these materials was found to be highly dependent on copper loading, with STO_4Cu emerging as the optimal catalyst—the NO conversion in NH₃-SCR on the level of 88% and exceptional N₂ selectivity (>98%) was obtained at 275 °C, despite an extremely low Cu content (below 2 wt.%). Lower copper content (STO_2Cu) in catalysts appears to limit the low-temperature activity, which correlates with a higher Cu(I) contribution. On the other hand, the higher copper loading (STO_10Cu) triggers their aggregation. Twelve-hour isothermal stability tests confirmed robust long-term performance and stable N₂ selectivity for both the NH₃-SCR (at 250 °C) and NH₃-SCO (at 375 °C) reactions, demonstrating the potential of finely dispersed, low-loading copper perovskites for environmental catalysis. Full article

Pharmaceutical compounds, emerging medicinal residues, and personal care products (PPCPs) are ubiquitous in aquatic environments and are causing a serious global environmental problem because of their persistence, bioaccumulation, and harmful effects on the environment and human health. Conventional wastewater treatment technologies are sometimes not capable of removing them completely, causing persistent releases of biologically active micropollutants to surface water, groundwater, and drinking water systems. In this context, biomass-derived catalysts are a promising class of advanced materials for environmental remediation because of their sustainable and cost-efficient nature. The catalysts are composed of bio-residues, such as agricultural residues, forestry wastes, and other bioresources, that have tunable surface chemistry, high porosity, and can be activated and functionalized to increase their catalytic activity. This review summarizes recent advances in biomass-derived catalysts for the removal of pharmaceuticals and PPCPs from water. Special attention is given to synthesis methods, such as pyrolysis, hydrothermal carbonization, chemical activation, heteroatom doping, and metal or metal-oxide hybridization. The catalytic mechanisms of pollutant degradation, including adsorption, radical-based advanced oxidation processes, and non-radical electron-transfer mechanisms, are critically discussed. Moreover, the effect of key operating parameters, catalyst stability, and real wastewater test performance are studied. Sustainability aspects such as green synthesis routes, integration of circular bioeconomy, and life-cycle aspects are also emphasized. Finally, current issues like catalyst deactivation, scaling-up, and the lack of a full mechanistic understanding are identified, and future research avenues are suggested to enable the implementation of efficient, durable, and environmentally friendly catalytic systems for large-scale wastewater treatment applications. Full article

Vanadium-doped cobalt ferrite nanoparticles, Co_1−xV_xFe₂O₄ (x = 0.0–0.04), were synthesized via a guar gum-assisted alkaline co-precipitation. Guar gum biopolymer proved to be a stabilizing and templating agent that improves vanadium incorporation and porous structure development. Both the as-synthesized and annealed Co-V catalysts are monophasic spinel ferrites, as determined by XRD. XRF and EDS confirmed the presence of Co, Fe, V, and O and allowed assessment of the elemental composition of the synthesized samples. The BET isotherms are of type IV, indicating that a mesoporous surface was formed. Vanadium doping increased the specific surface area approximately threefold, from 29.6 m²/g for CoFe₂O₄ to 86.24 m²/g for Co_0.97V_0.03Fe₂O₄. The vanadium-substituted cobalt ferrites were found to be effective catalysts in the decomposition of hydrogen peroxide and degradation of 4-nitrophenol. After annealing at 500 °C, the catalytic efficiency decreased by about half, indicating that the pristine surface of the as-synthesized ferrites has specific sites for H₂O₂ activation. The incorporation of vanadium atoms had a non-linear effect on catalytic performance. The optimal vanadium ion content for catalytic activity is x(V) = 0.03, as determined from the rate constants of H₂O₂ decomposition and 4-nitrophenol oxidation. The maximum degradation of 4-nitrophenol was recorded at 93% after 120 min. Measurements of ortho-phenylenediamine oxidation showed that CoV-0.03 is the most active radical-generating catalyst, confirming the close relationship between H₂O₂ decomposition and radical formation. XPS results confirm the catalytic redox cycling of Fe and Co ions, while subsurface V ions likely act as structural and electronic promoters. The obtained results identify Co_0.97V_0.03Fe₂O₄ as an effective magnetic catalyst for Fenton-like water treatment applications. Full article

Commercial carbon-based electrodes such as graphite felt and carbon felt in all-vanadium redox flow batteries suffer from inherent drawbacks, including slow vanadium ion redox kinetics, insufficient intrinsic catalytic activity, fiber corrosion, and functional group loss under strong acidic oxidative conditions, significantly limiting battery energy efficiency and long-term operational reliability. Rare-earth elements, with their unique 4f electron shell structure, tunable electronic levels, abundant surface oxygen vacancy defects, and strong coordination ability, offer a dual pathway—electronic and microstructural modulation—to optimize the interfacial electrocatalytic behavior of carbon electrodes, providing a novel materials system to overcome electrode performance bottlenecks in vanadium batteries. This review systematically summarizes recent advances in rare-earth-functionalized carbon electrodes and electrocatalysts for vanadium redox flow batteries, elaborating on core modification strategies, performance enhancement trends, and synergistic catalytic mechanisms. It also presents quantitative experimental results from the literature to clearly demonstrate the benefits: CeO₂-modified graphite felt at 0.2 wt% shows a 10.8% increase in energy efficiency compared to pristine graphite felt at a current density of 200 mA·cm⁻², while multi-rare-earth co-doped carbon electrodes achieve a 65% reduction in charge transfer resistance relative to unmodified electrodes. The review systematically categorizes two dominant modification routes—surface nano-decoration with rare-earth oxides and lattice bulk doping with rare-earth elements—and summarizes design principles and enhancement mechanisms of diverse composite catalytic systems, including rare-earth–carbon nanocomposites, rare-earth-based heterojunctions, and porous rare-earth catalysts. It further analyzes critical challenges in current research, such as unclear long-term stability mechanisms, high costs of high-purity rare-earth raw materials, immature large-scale fabrication processes, and limited in situ dynamic characterization techniques. Compared with existing reviews, this work clearly distinguishes between surface loading and lattice doping as two distinct rare-earth modification approaches, clarifying their differences in active site formation, electronic regulation logic, and cycling stability. It establishes a comprehensive theoretical framework for the coupled electronic–geometric effects in rare-earth-modified carbon electrodes, linking the intrinsic physicochemical properties of rare earths, material microstructure design, and battery electrochemical performance. Moreover, it innovatively proposes a pathway toward full-lifecycle recycling and reuse of rare-earth-based catalytic electrodes for industrial implementation. This review provides a complete theoretical foundation for developing high-performance, long-cycle, low-cost vanadium redox flow battery electrode materials and supports their engineering scale-up, contributing to the development of large-scale, long-duration energy storage technologies. Full article

Nickel–iron layered double hydroxides (NiFe-LDHs) are among the most active earth-abundant electrocatalysts for the oxygen evolution reaction (OER) in alkaline media, yet their performance remains sensitive to structure, electrolyte history, and testing practice. Unlike general summaries of NiFe-LDH synthesis and activity, this review emphasizes the dynamic nature of NiFe-LDHs as precatalysts, focusing on interlayer chemistry, electrolyte history, anodic reconstruction, mechanistic interpretation, and benchmarking reliability. It highlights the activation of NiFe-LDHs under anodic conditions into γ-NiFeOOH-like Ni–Fe oxyhydroxides, where Fe sites embedded in the NiOOH matrix and coupled Ni–Fe motifs jointly govern the catalytic activity. The discussion focuses on the role of layer charge, interlayer anions, layer spacing, and ion/water transport in reconstruction and catalytic activity. Catalyst crystallinity, orientation and loading are also related to common synthesis methods such as coprecipitation, hydrothermal growth and electrodeposition. Moreover, the main performance improvement strategies including defect engineering, heteroatom doping, conductive supports, and interlayer modification are discussed in relation to the adsorption of key OER intermediates. Finally, practical guidelines for reliable benchmarking are discussed, as well as the remaining challenges for the development of stable and efficient NiFe-LDH catalysts for alkaline electrolyzers. Full article

The electrocatalytic nitrogen reduction reaction (NRR) is a key approach for synthesizing green ammonia under mild conditions. However, the high bond energy of the N≡N triple bond makes N₂ difficult to activate, limiting the Faradaic efficiency. MoS₂ offers advantages such as low cost and abundant reserves as a non-precious-metal NRR electrocatalyst. Nevertheless, pure MoS₂ suffers from insufficient conductivity and a limited number of active sites, resulting in suboptimal catalytic performance. Herein, we develop a solvent-regulated one-step hydrothermal strategy using ethylene glycol as the sole reaction medium to fabricate an oxygen-substituted amorphous MoS₂ (O-MoS₂) electrocatalyst. XRD, SEM, and HRTEM characterization revealed that, as the ethylene glycol ratio increased, the product gradually transformed from a layered crystalline structure to a completely amorphous structure. XPS confirmed that oxygen atoms were uniformly incorporated into the MoS₂ lattice via substitution doping. Electrochemical testing showed that O-MoS₂ achieved an ammonia yield of 97.16 μg h⁻¹ mg⁻¹ and a Faradaic efficiency of 46.44% in a 0.1 M Na₂SO₄ electrolyte at −0.70 V vs. RHE, significantly outperforming undoped MoS₂ and semi-doped S-MoS₂. DFT calculations indicate that O doping reduces the N₂ adsorption energy, thereby synergistically promoting N₂ adsorption and activation. This dual-modification strategy provides a facile and universal guidance for electronic structure regulation of MoS₂-based catalysts and sheds new light on the design of high-efficiency ambient nitrogen fixation electrocatalysts toward practical green ammonia synthesis. Full article

The oxygen reduction reaction (ORR) remains a major kinetic bottleneck in fuel cells, metal-air batteries, and related electrochemical devices. Perovskite oxides are attractive ORR catalysts due to the ABO₃ lattice, which permits systematic control of transition-metal electronic structure, metal–oxygen covalency, and defect chemistry. This review compares low-temperature electrocatalytic ORR, including the 2e⁻ and 4e⁻ pathways, with high-temperature cathodic ORR in mixed ionic–electronic conductors, where oxygen adsorption, charge transfer, O=O bond cleavage, oxygen incorporation, and bulk transport are interlinked. The main optimization strategies, including A-site and B-site doping, defect engineering, nanostructuring, heterostructure/composite formation, and mechanisms, are discussed. Particular attention is given to the distinct requirements of fuel cells and metal-air batteries. Across these systems, perovskite ORR performance is governed by the joint evolution of surface chemistry, defect structure, and electrode architecture under operating conditions. Full article

Fe^II-doped zinc ferrite nanocrystals (Fe^II_xZn_1-xFe^III₂O₄) were prepared via a sol–gel approach in the presence of polyvinyl alcohol as a stabilizer and assessed for their capability to eliminate crystal violet (CV) dye from water-based solutions. The structural and surface characteristics of the prepared materials were examined by XRD, HRTEM, FESEM, ATR–FTIR, XPS, UV–visible spectrophotometer and BET analyses. XRD patterns confirmed the formation of a cubic spinel ferrite structure (Fd-3m), indicating successful incorporation of Fe^II into the ZnFe₂O₄ lattice. ATR–FTIR spectra showed characteristic metal–oxygen vibrations at the tetrahedral and octahedral sites. XPS analysis confirmed the coexistence of Fe^II and Fe^III species, which may promote interfacial charge transfer and redox reactions. HRTEM and FESEM images showed particle agglomeration and grain growth after calcination at 700 °C. Fe^II_0.2Zn_0.8Fe^III₂O₄ exhibited the highest photocatalytic performance, achieving 97.2% degradation of CV under optimized conditions. The effects of contact time, catalyst dosage, initial dye concentration, and pH were systematically studied. The maximum removal efficiency was obtained at pH 10 using 0.075 g catalyst for 20 mg L⁻¹ CV solution within 40 min. Freundlich isotherm models exhibited the strongest correlation (R² = 0.918), pointing to multilayer adsorption occurring across a non-uniform nanoparticle surface. The Dubinin–Radushkevich analysis returned an adsorption energy of 3.01 kJ mol⁻¹, implying that physical forces predominantly control the adsorption mechanism. Kinetic investigations revealed a two-stage CV uptake pathway: fast initial binding at exterior surface sites, succeeded by a slower migration of dye molecules into the internal pores of the adsorbent. Full article

Biomass-derived nanoengineered carbon materials have emerged as key platforms in environmental technologies due to their high surface area, electrical conductivity, chemical stability, and sustainable synthetic route starting from renewable feedstock. This broad family comprises dimensionally nanoscale materials, such as carbon dots, carbon nanofibers, and graphene-based structures, as well as biochars, hydrochars, activated carbons, and related porous carbonaceous materials whose pore architecture, surface chemistry, or defects are deliberately engineered at the nanometer scale. Beyond their traditional role as passive supports, these materials can actively regulate adsorption phenomena, charge transport, and catalytic microenvironments through precise control of heteroatom doping, graphitic domains, and hierarchical porosity. Among current environmental priorities, carbon dioxide (CO₂) management represents one of the most pressing challenges. Biomass-derived nanocarbons offer tunable adsorption sites for selective CO₂ capture while simultaneously serving as active matrices for catalytic conversion. Tailored doped-carbon frameworks can stabilize key reaction intermediates, suppress competing pathways such as hydrogen evolution, and promote selective transformation into fuels and high-value chemicals. In addition, these materials are excellent hosts for atomically dispersed metals, dual-site catalysts, and semiconductor hybrids used in electrochemical and photocatalytic CO₂ reduction. By combining renewable sourcing with nanoscale control of reactivity, carbon materials create a bridge between environmental remediation and carbon valorization. This review critically examines recent progress in biomass-derived nanoengineered carbon materials for integrated CO₂ capture and conversion, with emphasis on structure-property-performance relationships, mechanistic roles, scalability, and sustainability. Particular attention is also devoted to catalytic conversion and electrochemical CO₂ sensing, where carbon-based and hybrid interfaces enable the transduction of CO₂ recognition into measurable electrical responses. These materials represent a promising yet underexplored pathway toward circular carbon management and the development of next-generation low-carbon chemical technologies. Full article