Search Results (67)

The development of non-noble metal catalysts provides a cost-effective and sustainable route for glucose oxidation to gluconic acid. In this study, a series of catalysts based on inexpensive transition metals (Cr, Cu, Ni, Fe) and/or Au were synthesized using siliceous supports (SiO₂ and MCM-41) and systematically evaluated. The aim was to partially or fully replace noble metals with lower-cost alternatives, while maintaining high catalytic performance. Comprehensive characterization—including ICP-AES for composition, N₂ adsorption–desorption for porosity, XRD for structure, H₂-TPR for reducibility, and NH₃-TPD for acidity—was conducted to establish structure–property relationships. Among the tested catalysts, Ni- and Fe-based systems exhibited superior stability, with NiO/SiO₂ achieving gluconic acid yields comparable to Au. The bimetallic Au–Ni/SiO₂ catalyst displayed enhanced metal–support interactions and minimal leaching (<2%), while Au–Fe/SiO₂ improved selectivity, yielding up to 23% gluconic acid, surpassing 5Fe/SiO₂ (18%) and 0.3Au/SiO₂ (15%), albeit with lower stability. These results highlight the potential of low-cost transition-metal and bimetallic catalysts as efficient and economically viable systems for selective glucose oxidation, providing insights for rational catalyst design in sustainable carbohydrate valorization. Full article

This study investigates 49 gold solidi issued between the 4th and 5th century AD to determine their chemical composition. The coins were first catalogued by recording mass, diameter, and thickness. All specimens underwent non-destructive µ-EDXRF analysis to identify main elements, followed by semi-quantitative fineness evaluation. To validate these results, six coins were randomly micro-sampled: material was dissolved in aqua regia and analysed by ICP-AES for gold quantification and ICP-MS for high precision trace element determination. The non-destructive analyses showed consistently high gold percentages, confirming authenticity and the extensive use of this noble metal during the studied period. Two distinct groups were identified based on the XRF Pt/Pd ratio, suggesting the use of gold from different sources. Comparison of μ-EDXRF and ICP-AES gold contents shows no statistically significant differences; however, this apparent agreement should be interpreted cautiously, as it mainly reflects the limited resolving power of ICP-AES at very high gold concentrations rather than definitive evidence for the absence of surface-related effects. Trace elements analysis detected low concentrations of Cu, Sn, and Pb suggesting the use of alluvial gold for minting. The presence and correlation of terrigenous elements (Al, Ca, Ti, Cr, Mn, Fe, Ni, Zn, Sr) indicate soil as the burial site. Full article

This study presents a straightforward strategy for producing novel, effective and inexpensive functional non-noble metal-supported carbon materials made from abundant natural biomass. These materials offer a cost-effective alternative to noble metals for the oxidation of hydrazine (HzOR) and demonstrate the potential for widespread adoption of green, energy-saving hydrazine-based technologies in energy applications. Highly efficient and cost-effective iron (Fe) and manganese–iron (MnFe)-supported nitrogen-doped carbon (N–C) materials were developed using hydrothermal synthesis. Meanwhile, the N–C material was obtained from biomass—birch-wood chips—using hydrothermal carbonisation (HTC), followed by activation and nitrogen doping of the resulting hydrochar. The morphology, structure, and composition of the MnFe, MnFe/N–C, and Fe/N–C catalysts were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDS). The activity of the catalysts for HzOR in an alkaline medium was evaluated using cyclic voltammetry (CV). Depositing MnFe particles onto N–C was shown to significantly enhance electrocatalytic activity for HzOR compared to the Fe/N–C catalyst and especially to the MnFe particles catalyst in terms of highly developed porous structure, which offers the largest surface area, lowest onset potential, and highest current density response, resulting in the strongest catalytic activity. These results suggest that the MnFe/N–C catalyst could be a highly promising anode material for HzOR in direct hydrazine fuel cells (DHFCs). Full article

Listeria monocytogenes (LM) contamination constitutes a paramount global threat to food safety, necessitating the urgent development of advanced, rapid, and non-destructive detection methodologies to ensure food security. This study successfully synthesized Bi₂WO₆ nanoflowers through optimized feed ratios of raw materials and further functionalized them with noble metal Au to construct a high-performance Au-Bi₂WO₆ composite nanomaterial. The composite exhibited high sensing performance toward acetoin, including high sensitivity (R_a/R_g = 36.9@50 ppm), rapid response–recovery kinetics (13/12 s), and excellent selectivity. Through UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and X-ray photoelectron spectroscopy (XPS) characterizations, efficient electron exchange between Au and Bi₂WO₆ was confirmed. This electron exchange increased the initial resistance of the material, effectively enhancing the response value toward the target gas. Furthermore, the chemical sensitization effect of Au significantly increased the surface-active oxygen content, promoted gas–solid interfacial reactions, and improved the adsorption capacity for target gases. Compared to conventional turbidimetry, the Au-Bi₂WO₆ nanoflower-based gas sensor demonstrates superior practical potential, offering a novel technological approach for non-destructive and rapid detection of foodborne pathogens. Full article

The oxygen evolution reaction (OER) in water splitting involves complex multi-electron–proton transfer processes and represents the rate-determining step limiting overall electrolysis efficiency. Developing non-noble-metal catalysts with high activity and stability is therefore essential. Herein, a heterogeneous synthesis strategy was employed to in situ construct an iron-rich layered sulfate precursor (Fe_0.42Co_0.58-SO₄/NF) on nickel foam, which underwent deep self-reconstruction in alkaline electrolyte to form nanoflower-like Fe_0.42Co_0.58OOH/NF. The optimized catalyst maintained its iron-rich composition and hierarchical structure, delivering outstanding OER performance with an overpotential of 220 mV at 10 mA·cm⁻², a Tafel slope of 31.9 mV·dec⁻¹, and stability exceeding 12 h at 600 mA·cm⁻². Synchrotron analyses revealed dynamic transitions between mono-μ-O and di-μ-O Fe–M (M = Fe, Co) oxygen bridges during reconstruction, which enhanced both structural robustness and active-site density. The Fe-rich environment promoted the formation of Fe³⁺–O–Fe³⁺ units that synergized with Co⁴⁺ species to activate the lattice oxygen mechanism (LOM), thereby accelerating OER kinetics. This work elucidates the key role of oxygen-bridge geometry in optimizing catalytic activity and durability, providing valuable insights into the rational design of Fe–Co-based non-noble-metal catalysts with high iron content for efficient water oxidation. Full article

Ammonia serves as a critical industrial feedstock and a potential carbon-free energy carrier. However, its conventional synthesis method (the Haber–Bosch process) suffers from high energy consumption and substantial carbon emissions. The electrochemical nitrate reduction reaction (eNO₃RR) has emerged as a promising alternative pathway, capable of converting nitrate pollutants in water into high-value ammonia under mild conditions, enabling green synthesis while offering dual benefits of environmental remediation and energy conversion. Single-atom catalysts (SACs), with their maximal atom utilization efficiency, well-defined active sites, and highly tunable electronic structures, have demonstrated exceptional catalytic performance and selectivity in eNO₃RR. This review systematically summarizes recent advances of SACs in eNO₃RR, with a focus on reaction mechanisms, advanced in situ characterization techniques, theoretical calculation, and the catalytic behavior and structure–activity relationships of various non-noble metal centers (e.g., Cu, Fe, Co). Key strategies for enhancing SACs performance are elaborated, alongside an analysis of microenvironmental influences such as electrolyte composition, pH, and potential. Finally, we outlines current challenges in material design, dynamic active site identification, and the industrial application of SACs, and propose future research directions aimed at facilitating the practical implementation of eNO₃RR technology and contributing to the establishment of a sustainable ammonia economy. Full article

Proton exchange membrane fuel cells are playing a crucial role in the widespread adoption of hydrogen energy. However, their large-scale commercialization has been hampered by the high cost and limited durability of Pt-based electrocatalysts. To overcome the issues, researchers are focusing on Pt-non-noble metal (PtM) intermetallic electrocatalysts due to their superior activity and durability. This review highlights key advances in this field, starting with a comparison of intermetallic compounds and solid-solution alloys, and an analysis of the composition and structure of PtM intermetallics. It then proceeds to the controllable synthesis and structure characterization of the carbon-supported PtM intermetallics electrocatalysts. The review also thoroughly discusses their activity and durability for the oxygen reduction reaction (ORR). Finally, some perspectives on remaining challenges and future development of the PtM intermetallics electrocatalysts are presented to guide the exploitation of the active and durable intermetallic electrocatalysts with high metal content and small size for practical substitution. Full article

Non-enzymatic glucose sensing has attracted considerable interest as a promising alternative to enzyme-based sensors, addressing limitations such as poor stability and high cost. To overcome the challenges of expensive noble metals and the inherent issues of pure copper oxide (CuO), including low conductivity and aggregation tendency, this study developed a composite sensing material based on two-dimensional CuO nanosheets decorated with gold nanoparticles (Au NPs). A series of Au/CuO nanocomposites with varying Au loadings were synthesized through a combined hydrothermal and in situ reduction approach. Systematic electrochemical characterization revealed that the composite with 7.41 wt% Au loading exhibited optimal sensing performance, achieving sensitivities of 394.29 and 257.14 μA·mM⁻¹·cm⁻² across dual linear ranges of 5–3550 μM and 4550–11,550 μM, respectively, with a detection limit of 10 μM and a rapid response time of 3 s. The sensor also demonstrated selectivity against common interferents as well as long-term stability. This work highlights the importance of precise noble metal loading control in optimizing sensor performance and offers a feasible material design strategy for developing high-performance non-enzymatic glucose sensors. Full article

The ethanol oxidation reaction (EOR) is a key process for direct ethanol fuel cells (DEFCs), offering a high-energy-density and carbon-neutral pathway for sustainable energy conversion. However, the practical implementation of DEFCs is significantly hindered by the EOR due to its sluggish kinetics, complex multi-electron transfer pathways, and severe catalyst poisoning by carbonaceous intermediates. This review provides a comprehensive and mechanistically grounded overview of recent advances in EOR electrocatalysts, with a particular emphasis on the structure–activity relationships of noble metals (Pt, Pd, Rh, Au) and non-noble metals. The effects of catalyst composition, surface structure, and electronic configuration on C–C bond cleavage efficiency, product selectivity (C1 vs. C2), and CO tolerance are critically evaluated. Special attention is given to the mechanistic distinctions among different metal systems, highlighting how these factors influence reaction pathways and catalytic behavior. Key performance-enhancing strategies—including alloying, nanostructuring, surface defect engineering, and support interactions—are systematically discussed, with mechanistic insights supported by in situ characterization and theoretical modeling. Finally, this review identifies major challenges and emerging opportunities, outlining rational design principles for next-generation EOR catalysts that integrate high activity, durability, and scalability for real-world DEFC applications. Full article

Constructing heterojunction photocatalysts with efficient interfacial charge transfer is critical for solar-driven hydrogen evolution. In this study, a highly dispersed MoS₂/g-C₃N₄ composite was successfully synthesized via a stirring-assisted hydrothermal in situ growth strategy. The introduction of stirring during synthesis significantly enhanced the uniform dispersion of MoS₂ nanosheets and exposed abundant edge sites, leading to well-integrated heterojunctions with enhanced interfacial contact. Comprehensive structural and photoelectronic characterizations (XRD, SEM, TEM, EDS mapping, UV–Vis, TRPL, EIS, EPR) confirmed that the composite exhibited improved visible-light absorption, accelerated charge separation, and suppressed recombination. Under simulated solar irradiation with triethanolamine (TEOA) as a sacrificial agent, the optimized 24% MoS₂/g-C₃N₄-S catalyst achieved a high hydrogen evolution rate of 14.33 mmol·g⁻¹·h⁻¹ at a catalyst loading of 3.2 mg, significantly outperforming the unstirred and pristine components, and demonstrating excellent cycling stability. Mechanistic studies revealed that the performance enhancement is attributed to the synergistic effects of Type-II heterojunction formation and edge-site-rich MoS₂ co-catalysis. This work provides a scalable approach for non-noble metal interface engineering and offers insight into the design of efficient and durable photocatalysts for solar hydrogen production. Full article

Surface-enhanced Raman scattering (SERS) technology, leveraging its single-molecule-level detection sensitivity, molecular fingerprint recognition capability, and capacity for rapid, non-destructive analysis, has emerged as a pivotal analytical tool in food science, life sciences, and environmental monitoring. This review systematically summarizes recent advancements in SERS technology, encompassing its enhancement mechanisms (synergistic effects of electromagnetic and chemical enhancement), innovations in high-performance substrates (noble metal nanostructures, non-noble metal substrates based on semiconductors/graphene, and hybrid systems incorporating noble metals with functional materials), and its interdisciplinary applications. In the realm of food safety, SERS has enabled the ultratrace detection of pesticide residues, mycotoxins, and heavy metals, with flexible substrates and intelligent algorithms significantly enhancing on-site detection capabilities. Within biomedicine, the technique has been successfully applied to the rapid identification of pathogenic microorganisms, screening of tumor biomarkers, and viral diagnostics. For environmental monitoring, SERS platforms offer sensitive detection of heavy metals, microplastics, and organic pollutants. Despite challenges such as matrix interference and insufficient substrate reproducibility, future research directions aimed at developing multifunctional composite materials, integrating artificial intelligence algorithms, constructing portable devices, and exploring plasmon-catalysis synergy are poised to advance the practical implementation of SERS technology in precision diagnostics, intelligent regulation, and real-time monitoring. Full article

Acetone detection is crucial for non-invasive health monitoring and environmental safety, so there is an urgent demand to develop high-performance gas sensors. Here, platinum (Pt)-functionalized layered flower-like nickel ferrite (NiFe₂O₄) sheets were efficiently fabricated via facile hydrothermal synthesis and wet chemical reduction processes. When the Ni/Fe molar ratio is 1:1, the sensing material forms a Ni/NiO/NiFe₂O₄ composite, with performance further optimized by tuning Pt loading. At 1.5% Pt mass fraction, the sensor shows a high acetone response (R_g/R_a = 58.33 at 100 ppm), a 100 ppb detection limit, fast response/recovery times (7/245 s at 100 ppm), and excellent selectivity. The enhancement in performance originates from the synergistic effect of the structure and Pt loading: the layered flower-like morphology facilitates gas diffusion and charge transport, while Pt nanoparticles serve as active sites to lower the activation energy of acetone redox reactions. This work presents a novel strategy for designing high-performance volatile organic compound (VOC) sensors by combining hierarchical nanostructured transition metal ferrites with noble metal modifications. Full article

Proton exchange membrane fuel cells (PEMFCs) have been widely studied as an efficient and environmentally friendly energy conversion technology in recent years. However, the high cost, easy poisoning and complex synthesis methods of noble metal catalysts have hindered their commercialization. Therefore, in this paper, a non-noble metal composite catalyst CuFeCo/C for the oxygen reduction reaction (ORR) was prepared by using a facile liquid-phase reduction method. The ORR kinetic performance of CuFeCo/C was evaluated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and rotating ring-disk electrode (RRDE) tests. The results show that the oxygen reduction peak of CuFeCo/C appears at about 0.64 V, the half-wave potential is about 0.73 V, the limiting current density is about −16.51 A·m⁻², and the Tafel slope is about −0.08. The 10,800 s chronoamperometry test shows that the catalyst has a very good long-term cycle stability. This indicates that the CuFeCo/C composite catalyst has strong stability, good conductivity and ORR catalytic activity under alkaline conditions, which can promote the large-scale commercial application of PEMFCs. Full article

Hydrogen and oxygen serve as energy carriers that can ease the transition of energy due to their high energy densities. Nonetheless, their production processes entail the development of efficient and low-cost storage and conversion technologies. In this regard, photoelectrocatalysts are materials based on the photoelectronic effect where electrons and holes interact with H₂O, producing H₂ and O_2, and in some cases, this is achieved with acceptable efficiency. Although there are several reviews on this topic, most of them focus on traditional semiconductors, such as TiO₂ and ZnO, neglecting others, such as those based on non-noble metals and organic ones. Herein, semiconductors like CdSe, NiWO₄, Fe₂O₃, and others have been investigated and compared in terms of photocurrent density, band gap, and charge transfer resistance. In addition, this brief review aims to discuss the mechanisms of overall water-splitting reactions from a photonic point of view and subsequently discusses the engineering of material synthesis. Advanced composites are also addressed, such as WO₃/BiVO₄/Cu₂O and CN-FeNiOOH-CoOOH, which demonstrate high efficiency by delivering photocurrent densities of 5 mAcm⁻² and 3.5 mA cm⁻² at 1.23 vs. RHE, respectively. Finally, the authors offer their perspectives and list the main challenges based on their experience in developing semiconductor-based materials applied in several fields. In this manner, this brief review provides the main advances in these topics, used as references for new directions in designing active materials for photoelectrocatalytic water splitting. Full article

A sustainable reaction of electrocatalytic nitrate conversion in ammonia production (NO₃RR) occurring under ambient conditions is currently of prime interest, as well as urgent research due to the real potential replacement of the environmentally unfavorable Haber–Bosch process. Herein, a series of electrocatalysts based on two-component cobalt alloys was synthesized using low-cost non-noble metals Co, Fe, Cr, and also Si. The samples of electrocatalysts were characterized and studied by the following methods: SEM, EDX, XRD (both transmission and reflection), UV–VIS spectroscopy, optical microscopy, linear (and cyclic) voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Beyond that, the determination of electrochemically active surface area was also carried out for all samples of electrocatalysts. Unexpectedly, the sample having an intermetallic compound (IMC) of the composition Co₂Si turned out to be the most highly effective. The highest Faradaic efficiency (FE) of 80.8% at E = −0.585 V (RHE) and an ammonia yield rate of 22.3 µmol h⁻¹ cm⁻² at E = −0.685 V (RHE) indicate the progressive role of IMC as the main active component of the electrocatalyst. Thus, this study demonstrates the promise and enormous potential of IMC as the main component of highly efficient electrocatalysts for NO₃RR. This work can serve primarily as a starting point for future studies of electrocatalytic conversion reactions in the production of ammonia using IMC catalysts containing non-noble metals. Full article