Search Results (2,388)

To overcome active site blockage and poor interfacial contact in traditional syntheses, PtNi bimetallic nanoparticles were grown in situ on a microporous carbon paper via pulse electrodeposition. Firstly, the impact of deposition potential was investigated. The results indicate that the deposition potential significantly modulates the surface Pt⁰/Pt²⁺ ratio; concurrently, a shift toward more negative potentials intensified nanoparticle agglomeration. The effects of the duty cycle were investigated at an optimal deposition potential of −0.95 to −0.4 V. A duty cycle of 30% yielded the optimal Pt⁰/Pt²⁺ ratio. Furthermore, TEM revealed a coexisting strain profile of bulk PtNi lattice contraction and localized expansion at peripheral Pt (111) facets. This synergistic tuning of surface valence and strain optimizes the thermodynamic balance between oxygen adsorption and intermediate desorption on Pt sites. In summary, the optimal catalyst, prepared at a deposition potential of −0.95 V and a duty cycle of 30%, showed the best reaction behavior in the oxygen reduction reaction with an initial onset potential of 0.92 V (vs. RHE). After 5000 cycles of testing, the catalyst showed a constant durability, with the onset potential degrading only marginally to 0.87 V. This work successfully demonstrates that the surface morphology and valence states of the catalyst can be effectively tailored by regulating the pulse voltage and duty cycle. Full article

The oxygen evolution reaction (OER), a key half-reaction in electrochemical water splitting, is limited by sluggish multi-electron transfer kinetics, starting extensive research into efficient, low-cost nanoscale electrocatalysts, particularly those based on nickel, cobalt, and iron, as well as mixed-metal, hybrid, and heteroatom-doped carbon-based metal-free systems, as presented here. Ni- and Co-based electrocatalysts show high efficiency for alkaline OER due to optimized nanostructures, surface modifications, heterostructure design, and multi-metal doping, which enhance activity, stability, and electronic properties. Their performance relies on precise atomic-level control of structure and synergistic interactions, enabling them to approach or rival noble-metal catalysts. Iron-based electrocatalysts are also promising due to their abundance, low cost, and flexible redox chemistry, forming active iron oxyhydroxide species during operation; however, their low conductivity requires structural and electronic optimization. Beyond Fe, Ni, and Co, copper-based compounds, zeolitic imidazolate framework-derived structures, and manganese phosphide–cerium oxide composites offer enhanced oxygen vacancies, tunable structures, and strong interfacial synergy. Furthermore, heteroatom-doped carbon materials incorporating nitrogen, phosphorus, or sulfur improve catalytic activity by modifying electronic structure, creating active sites, and enhancing charge transfer. Overall, careful control of composition, structure, and electronic properties enables the development of efficient, durable, and scalable noble-metal-free catalysts for OER. Full article

Driven by the growing global energy demand and the pursuit of carbon utilization goals, dry reforming of methane (DRM) has attracted considerable attention for its ability to convert CO₂ and CH₄ into syngas. Biogas, an eco-friendly product of processes such as anaerobic digestion, is primarily composed of CO₂ and CH₄ and ideally meets the feedstock requirements for DRM. In practice, biogas is generated via anaerobic digestion of livestock manure and other organic waste, providing a stable and sustainable source for the DRM reaction and thus enabling waste valorization. Supported Ni⁰ catalysts have become a research focus in this field due to their high catalytic activity and moderate cost. Conventional particulate Ni⁰ catalysts, however, are prone to carbon coking in fixed-bed applications and are difficult to effectively recover and regenerate after the reaction; thus, they are often being discarded, leading to resource waste and environmental burden. To address these issues, this study has designed a novel metal-sintered fleece catalyst support and developed a corresponding reactor. The effects of the catalyst preparation method, activation conditions, and the support structure on DRM performance have been systematically investigated. The spent Ni-based catalyst could be regenerated via calcination to restore catalytic activity and enable multiple cycles of use, significantly extending the catalyst’s lifespan and offering both economic and environmental benefits. Experimental results have demonstrated that the reactor achieved a conversion rate exceeding 80% with near-complete product selectivity. Full article

Developing sustainable electrode materials from renewable biomass is important for improving the environmental sustainability of lithium-ion batteries (LIBs). Sugarcane bagasse lignin, an abundant agricultural byproduct, is a promising precursor for lignin-derived carbon anode materials, yet systematic comparative studies on catalyst-dependent structure evolution and LIB performance remain limited. In this study, lignin extracted from sugarcane bagasse by an ethanosolv process was converted into Fe- and Ni-catalyzed lignin-derived carbon materials via catalytic pyrolysis at 900 °C. The effects of catalyst type, metal-to-lignin ratio, and pyrolysis holding time on textural properties, structural features, and electrochemical behavior were systematically investigated. Among the studied conditions, the Fe-catalyzed sample prepared at a metal-to-lignin ratio of 1:2.5 and a holding time of 3 h (GLKL-2.5Fe-3h) exhibited the highest BET surface area (332.71 m² g⁻¹) and the most developed porous morphology. SEM, TEM, Raman, and XRD analyses indicated catalyst-dependent differences in pore development, carbon domain morphology, and local graphitic ordering, with Fe- and Ni-catalyzed samples following distinct structural evolution pathways. Electrochemical testing showed that GLKL-2.5Fe-3h delivered the highest initial discharge capacity (759 mAh g⁻¹), retained 165 mAh g⁻¹ after 500 cycles, and exhibited more favorable rate performance and lower apparent interfacial resistance than the other tested samples under the same conditions. In contrast, the Ni-catalyzed and solvothermally treated samples showed lower capacity retention and/or less favorable electrochemical behavior. These results demonstrate the strong effect of catalyst type on the structure-performance relationship of bagasse lignin-derived carbon anodes and support Fe-catalyzed lignin-derived carbon as a promising sustainable anode candidate for LIB applications. Full article

The nickel-derived metal–organic framework (MOF), Ni-BTB, synthesized from 4,4′,4″-benzene-1,3,5-tribenzoic acid (H₃BTB), was investigated as a multifunctional platform for enhanced energy applications including production and storage. In catalytic hydrogen generation by NaBH₄ hydrolysis, Ni-BTB attained a hydrogen generation rate (HGR) of 4640 mL H₂/g•min with 1 mg of catalyst, with an activation energy of 76.44 kJ/mol. Under optimized reaction conditions (60 °C, 20 mg catalyst, and 1 g NaBH₄), the HGR increased to 9542 mL H₂/g•min, while exhibiting high recyclability throughout four successive cycles. As a supercapacitor electrode, Ni-BTB achieved a specific capacitance of 156 F/g at 1 A/g and showed remarkable cycling stability, maintaining its capacitance after 10,000 charge–discharge cycles. Furthermore, Ni-BTB exhibited exceptional electrocatalytic activity for oxygen evolution reaction (OER), requiring only 106 mV overpotential to achieve 10 mA/cm², offering a time-of-flight (TOF) of 0.0585 s⁻¹ and demonstrating significant operational longevity of at least 12 h. These findings underscore Ni-BTB as a durable, reusable, and adaptable material for hydrogen production, energy storage, and electrocatalytic applications. Full article

Salophen-type Schiff base ligands derived from salicylaldehyde and naphthalene aldehydes were synthesized and coordinated to Ni(II) to obtain three nickel complexes (NiL1–NiL3), which were evaluated as heterogeneous electrocatalysts for the methanol electro-oxidation reaction (MOR) in alkaline media. The ligands and complexes were fully characterized by FT-IR, ¹H NMR, EPR, DART-MS, and elemental analysis, confirming tetradentate coordination through imine nitrogen and phenoxide oxygen donors. Electrochemical studies were carried out using carbon paste electrodes modified with 15 wt % of each complex. Cyclic voltammetry revealed that the electrocatalytic activity is mediated by the Ni(II)/Ni(III) redox couple, with Ni(III) oxohydroxide species acting as the active sites for methanol oxidation. Among the evaluated systems, NiL1@CPE showed superior performance at low methanol concentrations, while NiL2@CPE and NiL3@CPE exhibited higher current densities at elevated methanol concentrations. Scan-rate studies indicated that the oxidation process is diffusion-controlled, and a linear response to methanol concentration was observed over a wide concentration range. The results demonstrate that ligand structure and coordination geometry play a crucial role in modulating the electrocatalytic behavior of Ni(II) Schiff base complexes, highlighting their potential as cost-effective molecular catalysts for alkaline methanol oxidation. Full article

Catalytic materials are central to the advancement of hydrogen generation technologies, playing a pivotal role in enabling sustainable, carbon-neutral energy systems. Hydrogen can be produced via electrochemical water splitting, thermochemical reforming, or photocatalysis—each imposing unique performance requirements on catalysts in terms of activity, selectivity, stability, and efficiency. While traditional noble metals (e.g., platinum, ruthenium, iridium) provide benchmark catalytic activity, their widespread use is hindered by scarcity, high cost, and limited long-term durability. Consequently, researchers have increasingly focused on earth-abundant alternatives such as transition metals (Ni, Co, Fe, Mo), alloys, metal oxides, carbides, sulfides, nitrides, and carbon-based systems. Among these, two-dimensional materials, particularly the MXene family, have attracted significant attention due to their metallic conductivity, layered structure, and tunable surface chemistry. These features enable rapid charge transfer and abundant active sites, making MXenes and related nanostructured catalysts promising for both the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) across a wide range of electrochemical conditions. Parallel efforts have integrated novel semiconductors, plasmonic nanomaterials, and hybrid heterostructures to improve the efficiency of solar-to-hydrogen energy conversion. This paper reviews the main types of catalytic materials used in hydrogen production, explains their design strategies and structure–performance relationships, and discusses key engineering challenges such as integrating renewable energy sources, scaling up manufacturing, and ensuring long-term durability in real-world systems. Future research goals are also highlighted, including the development of affordable non-noble catalysts, enhancing catalyst stability through surface and defect engineering, and coupling hydrogen production with circular economy principles, all of which are essential to making hydrogen generation more efficient, scalable, and cost-effective as the world transitions to clean and sustainable energy. Full article

It is necessary to find sustainable alternatives to the conventional fossil fuels used by the transportation sector today. For the hard-to-abate aviation and heavy transport, liquid hydrocarbon fuels derived from biomass via pyrolysis are a viable option. Biomass pyrolysis oils need upgrading by hydroprocessing before they can be further processed into fuels at a refinery. Due to reactor plugging and catalyst deactivation in one-step hydroprocessing, it has been proposed to add a stabilization step at a lower temperature to convert the most reactive compounds in pyrolysis oil, such as carbonyls, to less reactive species such as alcohols. Three different catalysts, Ni/Al₂O₃, sulfided NiMo/Al₂O₃, and Pt/Al₂O₃, were studied for stabilizing three different model compounds, furfural, guaiacol, and octanoic acid, alone and as a mixture in a batch reactor at 90 bar initial H₂ pressure and 180 °C. The order of performance was determined to be Ni/Al₂O₃ > Pt/Al₂O₃ > sulfided NiMo/Al₂O₃ in these conditions. The Ni/Al₂O₃ catalyst showed both the highest overall conversion, the most fully hydrogenated compounds, and the highest carbonyl conversion. The effect of adding 1172 wt-ppm sulfur to the feed was also investigated, which showed that Ni/Al₂O₃ was the most sensitive catalyst to sulfur poisoning. Full article

In this study, FeCoNiMoCu high-entropy alloy thin films were sulfided at different temperatures ranged from 250 °C to 450 °C by chemical vapor deposition, and the resultant sulfided Fe-Co-Ni-Mo-Cu-S alloys were characterized by means of XRD, SEM, XPS and EDS. HER performance tests were carried out in four electrolyte systems, namely 0.5 M H₂SO₄, 1 M KOH, 1 M KOH + 0.5 M NaCl and 1 M KOH + 1 M Na₂S. The results indicated that the as-prepared electrodes exhibited low HER overpotentials in all four electrolytes, with the optimal catalytic performance consistently achieved at a sulfidation temperature of 350 °C. Among the tested systems, the electrode delivered the best HER activity in 0.5 M H₂SO₄, showing an overpotential of merely 53 mV and a Tafel slope of 86.72 mV dec⁻¹ at a current density of 10 mA·cm⁻². In 1.0 M KOH, the overpotential required to reach the same current density was 98 mV with a Tafel slope of 72.43 mV dec⁻¹. For the mixed electrolyte of 1 M KOH and 0.5 M NaCl, the overpotential at 10 mA·cm⁻² was 142 mV accompanied by a Tafel slope of 49.51 mV dec⁻¹. In contrast, the 1 M KOH + 1 M Na₂S electrolyte yielded an overpotential of 77 mV and a Tafel slope of 84.01 mV dec⁻¹ at the identical current density. HER tests revealed that the sulfidation temperature exerts a significant influence on the formation and distribution of active phases of multi-metal sulfides (e.g., FeS_x, CoS_x, NiS_x, MoS₂) on the electrode surface. The electrodes prepared at an appropriate sulfidation temperature exhibit a larger specific surface area and enhanced hydrogen evolution reaction performance for water electrolysis. These findings may provide useful references for other researchers in the design and fabrication of high-entropy alloy-based HER catalysts. Full article

Engineering carbon nanostructures directly on carbon fiber fabrics offers an effective route to constructing hierarchical multifunctional coating systems. In this study, methane-based chemical vapor deposition (CVD) was employed to investigate nanocarbon coating formation on woven carbon fabrics supported by electrodeposited Ni catalysts. Catalyst morphology was systematically engineered through surface pretreatment, electric-field configuration, and pulse electrodeposition. At 700 °C, methane activation was insufficient to sustain continuous nanocarbon growth, indicating a temperature-dependent activation threshold. Raising the growth temperature to 900 °C enabled sustained methane decomposition and produced dense nanocarbon coatings; hydrogen assistance suppressed amorphous deposition and promoted more ordered nanofilament features. Pulse electrodeposition refined Ni catalyst dispersion and nucleation density, improving coating uniformity compared with direct-current deposition. Structural ordering was further supported by Raman spectroscopy (D and G bands with an average ID/IG of 0.678 ± 0.068 for methane-grown samples versus 0.798 ± 0.011 for electrodeposition-only controls) and by HRTEM revealing multi-layer graphitic walls (~0.34 nm interlayer spacing). Together, the results support a methane-derived dissolution–diffusion–precipitation growth pathway governed by catalyst morphology, temperature, and gas composition. This controllable, textile-compatible catalyst engineering approach provides a scalable route to hierarchical graphitic coatings for carbon-fabric-based composites, electromagnetic interference shielding, and thermal management applications. Full article

This review analyzes the catalytic routes for the Power-to-X (PtX) conversion of hydrogen to methane, methanol, ammonia, formic acid, and synthetic hydrocarbon fuels. The key reactive synthesis technologies and catalysts for each vector are described. Recent studies and pilot projects summarizing the reaction pathways of each vector and the associated catalyst technologies are also discussed. The analysis indicates that catalyst selection critically influences the efficiency and selectivity of these reactive systems. Some catalyst synthesis routes rely on expensive critical minerals (e.g., Ru and Rh), which raise technical and economic challenges for their industrial application. Catalyst deactivation and scale-up limitations are also relevant issues to be resolved. Emerging catalysts (e.g., Fe–Co or Co–Ni bimetallics, core–shell materials, metal-organic frameworks (MOFs), electrides, covalent-organic frameworks (COFs), and perovskites) are being explored to enhance stability, selectivity, and deactivation. Europe leads PtX development to consolidate the industrial production of hydrogen-based vectors with strong policy support, while the industrial initiatives in Latin America are limited (for instance, Chile’s green methanol and ammonia projects are examples) despite its great potential to generate renewable energy. In summary, Power-to-X can store renewable energy and close the carbon loop; however, its industrial consolidation demands catalyst innovation and supportive regulatory frameworks to overcome the challenges highlighted in this review. Full article

The manipulation of the electrocatalyst nanoarchitecture, particularly transition metal compounds, regarding size, shape, facets, and composition, significantly enhances the electrocatalytic activity in energy transformations. This study introduces a novel methodology for the precipitation of mesoporous nanoparticles of nickel tungstate (meso-NiWO₄) using direct chemical deposition from a template of Brij^®78 surfactant liquid crystal. Physicochemical analyses revealed the formation of amorphous meso-NiWO₄ nanoparticles with dual sizes of 10 ± 3 and 120 ± 8 nm and a specific surface area of 34.2 m²/g, exceeding that of nickel tungstate deposited in the absence of surfactant (bare-NiWO₄, 4.0 m²/g). The meso-NiWO₄ nanoparticles exhibit improved electrocatalytic stability, reduced charge-transfer resistance (R_ct = 1.11 ohm), and a current mass activity of ~365 mA/cm² mg at 1.6 V vs. RHE during the electrolysis of urea in alkaline solution. Furthermore, by employing meso-NiWO₄ in a two-electrode urea electrolyzer, a remarkable 4.8-fold increase in the cathodic hydrogen concurrent production rate was achieved (373.40 µmol/h at a bias potential of 2.0 V), compared to that of the bare-NiWO₄ catalyst. The exceptional urea oxidation electroactivity and the enhanced hydrogen evolution rate arise from substantial specific surface area and mesoporous structure, facilitating effective charge transfer and mass transport through the meso-NiWO₄ catalyst. Using the surfactant liquid crystal template for electrocatalyst synthesis enables a one-pot deposition of diverse nanoarchitectures and compositions with high surface area at ambient conditions for an improved electrocatalytic and hydrogen green production process. Full article

Advanced oxidation technology utilizing ozone as the oxidant shows great potential for the efficient purification of wastewater. However, the efficiency of ozone decomposition remains a significant bottleneck limiting the performance of ozone-based advanced oxidation processes. Catalytic ozone decomposition technology is a highly effective approach to enhancing ozone utilization efficiency; nevertheless, the competing adsorption of water molecules results in low catalytic reaction efficiency and catalyst deactivation. In this study, NiFe layered double hydroxide (LDH) was prepared successfully through the hydrothermal method. In situ DRIFTS with isotope labeling revealed that ozone combines with surface H atoms to produce H₂O, whereas the oxidation of high-valence metals destroys H₂O, producing H atoms that return to the surface of NiFe LDH. The unique structure of NiFe LDH allows water to participate in the surface H atom cycle process, and the charge exchange between Ni and Fe atoms accelerates the recovery of surface H atoms, which avoids the deactivation of the active site caused by competitive adsorption of water molecules, achieving a catalytic ozone decomposition efficiency of 99% for 80 h and 59.0% for simulated wastewater containing polyacrylamide as a model pollutant. This work presents a fresh insight into surface H cycling of LDH materials to improve the wet resistance of the catalysts. Full article

CoNi layered double hydroxides (CoNiLDHs) were successfully synthesized on nickel foam (NF) using a hydrothermal method. X-ray diffraction (XRD) analysis confirmed the formation of a well-defined hydrotalcite-like phase, including a strong (003) peak, indicating layered stacking. Scanning electron microscopy (SEM) revealed a 3D hierarchical nanosheet structure resembling flower-like arrays, which was further supported by EDS mapping showing a uniform distribution of Co, Ni, and O. Electrochemical studies demonstrated excellent OER activity, with a low overpotential of 188 mV at 10 mA/cm² and a Tafel slope of 97.48 mV/dec, inferring rapid reaction kinetics. Furthermore, the material exhibited a significant electrochemical surface area (ECSA) compared to bare NF. Chronoamperometry over 24 h confirmed the operational durability catalyst, stabilizing around 7–8 mA/cm², validating its potential as a cost-effective and efficient OER electrocatalyst in alkaline media. Full article