Electrocatalysis最新文献

A promising Ru-Pt-Ni/AC catalyst for direct glucose fuel cells was developed via the supercritical carbon dioxide deposition method which enabled a uniform distribution of metals, with an average particle size of 3.85 nm. The electrocatalytic activity and stability of the nanocatalysts for glucose electrooxidation were evaluated using chronoamperometry (CA), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) in alkaline media. Under these conditions, the catalyst exhibited a notably high specific activity of 3.98 mA·cm⁻² for glucose electrooxidation, significantly surpassing the performance of conventional catalysts. Electrochemical impedance spectroscopy further confirmed the kinetic improvement, showing a clear reduction in charge transfer resistance with increasing potential. Complementary DFT calculations supported the experimental findings by evidencing modifications in surface electrophilicity and their role in activity enhancement.

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Single-atom catalysts (SACs) are highly attractive for electrochemical energy conversion owing to their unique electronic structures, high intrinsic activity, and maximum atom utilization. Here, we report density functional theory (DFT) investigations of metal-doped porphyrins functionalized with electron-withdrawing (F) and electron-donating (NH₂) groups to elucidate their bifunctional catalytic activity toward the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Electronic structure analyses, including HOMO–LUMO distributions, molecular electrostatic potential (MESP), and X-ray absorption spectra (XAS), reveal that the NH₂-functionalized Rh-porphyrin system, (RhPp)N₈(NH₂)₈, exhibits a highly favorable electronic environment for catalytic activation. Free-energy calculations show that all ORR steps are exothermic with an overall ΔG of –4.79 eV, while HER proceeds preferentially via the Volmer–Tafel pathway due to a lower Tafel barrier relative to the Heyrovsky step. Notably, the (RhPp)N₈(NH₂)₈ surface delivers exceptionally low overpotentials of 0.26 V for ORR and –0.01 V for HER, on par with benchmark Pt(111) (0.45 V for ORR and –0.09 V for HER). These results identify functionalized Rh-porphyrins as efficient bifunctional electrocatalysts, for next-generation fuel cells and water-splitting technologies.

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Oxygen reduction reaction (ORR) has attracted great deal of scientific attention owing to its enormous applications in fuel cells and batteries. Recently, several attempts have been made to explore non-precious metal based electrocatalysts for ORR to enhance the commercial availability of the process. This study presents one pot facile synthesis of cobalt phosphide supported on reduced graphene oxide (CoP@rGO) via hydrothermal process for application as electrocatalyst for ORR. Characterization of synthesized electrocatalyst revealed high surface area and homogeneous dispersion of CoP over the rGO sheets. The electrochemical properties of the catalyst towards ORR were studied in comparison to pristine CoP and Pt/C (20%); by using rotating disc electrode (RRDE) system. The catalyst was found to have excellent ORR performance with E_onset and E_1/2 of 0.92 V and 0.81 V vs RHE, respectively. The smaller values of Tafel slope i.e. 44.8 mV/dec as compared to CoP 117 mV/dec and Pt/C (20%) 71 mV/dec, suggested fast reaction kinetics with significantly high catalytic activity. CoP@rGO showed high selectivity for ORR following 4 electron pathway; with average electron transfer number (n) of 3.76, which suggest direct reduction of O₂ to H₂O. Moreover, excellent operational stability of electrocatalyst was observed via current density retention ~ 95% in O₂ saturated 0.1 M KOH solution after continuous chronoamperometric testing for 20000 s.

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Developing portable, accurate, cost-effective hydrogen peroxide (H₂O₂) detection platforms is essential for industrial applications and early disease diagnosis. Metal–organic frameworks (MOFs) based composites integrated with metal nanoparticles have been intensively investigated in electrochemical sensing, attributable to their unique architecture and performance characteristics. Herein, PdNPs@NH₂-MIL-101(Fe) nanocomposites were synthesized via a green reduction process using tannic acid and applied in the development of an enzyme-free electrochemical sensor for H₂O₂ detection. The synergistic effect of the Pd nanoparticles and the MOFs matrix provided abundant active sites and enhanced electron transfer capability, enabling the sensor to exhibit excellent electrocatalytic performance. Under optimal conditions, the sensing platform exhibited a wide linear response from 10 μM to 15 mM, with a detection threshold of 3.6 μM (S/N = 3). Furthermore, the sensor achieved reliable detection of exogenous H₂O₂ in commercial mouthwash samples and intracellularly generated H₂O₂ by cancer cells (HepG2), underscoring its effectiveness in practical scenarios. This work presents a novel strategy for synthesizing high-performance composite nanomaterials and offers valuable insights into the large-scale application of electrochemical sensors for H₂O₂ detection.

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The creation of effective and affordable water oxidation catalysts is a major obstacle to enhance the performance of large-scale energy solutions based on electricity-driven hydrogen generation from water. Significant attempts were made to increase the catalytic efficiency of electrocatalysts derived from 3D-transition metals, particularly those based on cobalt, which are seen to be viable options for non-noble catalysts in electrocatalytic water splitting. In the present article, we have synthesized various stoichiometries of cobalt tungstate via a one-pot hydrothermal method. The prepared catalysts were then thoroughly characterized by X-ray diffraction patterns (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). Afterwards, electrochemical studies like linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization analysis were done to test the potential of the electrocatalysts for the oxygen evolution reaction (OER) in a basic environment. Among the various stoichiometries, the lowest overpotential was found to be 220 mV for CoWO₄ to provide 10 mA cm⁻² current density (η₁₀), which is better than the benchmarking IrO₂ (313 mV). Further, it has the lowest R_ct and Tafel slope of 56 Ω and 75 mV dec⁻¹, respectively, among other prepared catalysts.

This study reported the loading of a lanthanum (La)-doped CoFe₂O₄ spinel catalyst onto alkalized MXene. The La-doped CoFe₂O₄ electrocatalyst was prepared via in situ doping and growth. Importantly, the inherent stacking flexibility of MXene was exploited to engineer the interface. NaOH etching induced the formation of surface wrinkles, thereby mitigated the issue of layer re-stacking. Additionally, the etching process increased the surface density of -OH functional groups on the MXene surface, enabling these negatively charged groups to bind more readily with cations. As a result, the MXene’s affinity for hetero-bonding with transition metal compounds was enhanced. La doping was demonstrated to have enhanced intermediate adsorption/desorption capacity, attributed to La’s ability to facilitate electron transfer from Co to Fe, thereby increasing the electron density of Fe and improving catalytic performance. The electrocatalyst exhibited remarkable activity for both hydrogen evolution and oxygen evolution reactions, with overpotentials of 164 and 263 mV at − 10 and 10 mA cm⁻², respectively. Furthermore, the overall water-splitting system Maintained a low cell voltage, stabilized at 1.638 V at a current density of 10 mA cm⁻². In summary, La₀.₂CoFe₁.₈O₄/alkalized-MXene overcame the aforementioned challenges, demonstrated excellent bifunctional catalytic capabilities, and maintained high performance and stability. This work proposed a novel and practical strategy employing alkalized MXene as a substrate and incorporating rare earth elements into the spinel structure to enhance catalyst performance.

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La₀.₂CoFe₁.₈O₄/MX exhibits outstanding OER performance in alkaline environments; La doping of the spinel structure CoFe₂O₄ with rare-earth lanthanum.

Among naturally occurring polymers, lignin is the most abundant source of aromatic compounds. Electrocatalytic valorization of lignin derivatives into value-added chemicals represents a sustainable and promising strategy, leveraging the increasing accessibility of intermittent renewable electricity and abundant biomass feedstocks. Compared to the thermal catalytic conversion, electrocatalytic hydrogenation (ECH) and hydrodeoxygenation (HDO) are emerging as key technologies for biomass conversion, owing to their ability to utilize renewable electricity for in situ generation of environmentally benign H₂ and other essential reagents. Recent progress in ECH and hydrogenolysis of lignin-derived oxygenated aromatic compounds has demonstrated viable pathways for synthesizing industrially critical chemicals, offering a potential alternative to fossil resource dependency. Nevertheless, research on catalyst design, reaction mechanisms, and system optimization for the electrocatalytic upgrading of lignin derivatives remains in its early stages, necessitating further fundamental and applied investigations. This review begins by providing a comprehensive overview of electrocatalytic hydrogenation and hydrogenolysis processes applied to lignin-derived substrates. Finally, challenges facing and future opportunities for electrocatalytic lignin valorization pathways are discussed.

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In this paper, Ni@Co₃O₄-s-rGO was synthesized and constructed as a non-enzymatic sensor to detect hydrogen peroxide (H₂O₂). The prepared sample was characterized using SEM–EDX, UV–vis, XRD, and Raman spectroscopy. In 0.1 M phosphate-buffered saline (PBS), the fabricated Ni@Co₃O₄-s-rGO amperometric sensor demonstrated a high sensitivity of 160.3 µA·mM⁻¹ towards H₂O₂ within the linear detection range of 1 to 2000 µM. The detection limit was also determined as 3.6 µM. Furthermore, the Ni@Co₃O₄-s-rGO catalyst demonstrated high selectivity towards H₂O₂, even in the presence of common interferents. The enhanced electrochemical sensing ability of the catalyst is attributed to the synergy of three factors: the relatively large electrode active area, the high electrical conductivity, and the electron mobility in the presence of ultra-nanosized Ni particles.

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Hydrogen production via water electrolysis has garnered significant attention as a pivotal technology for green energy conversion. In this work, cheap metal ions copper and iron are used as catalyst raw materials to develop high efficiency and low cost HER catalyst. Copper-doped iron phosphide supported on carbon paper (Cu-FeP/CP) is synthesized via a simple two-step process involving hydrothermal growth followed by high-temperature phosphidation. The morphology and electrochemical performance of iron phosphide catalysts with controlled copper doping are investigated. A nano-needle-like Cu-FeP/CP structure with 3% Cu doping exhibits a high surface area, providing abundant active sites, while Cu-induced charge redistribution and Fe-Cu synergy further enhance its intrinsic catalytic activity. HER catalytic performances results reveal Cu-FeP/CP-3% electrode exhibits low overpotentials of 71 mV in 0.5 M H₂SO₄ and 123 mV in 1 M KOH to achieve a current density of 10 mA cm⁻², along with small Tafel slopes of 49 mV dec⁻¹ and 72 mV dec⁻¹, respectively. Additionally, Cu-FeP/CP-3% shows low charge transfer resistance and stable HER performance over 24 h. The result provides new insights into the design and fabrication of highly efficient and cost-effective HER catalysts.

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Over the years, there has been a surge in the quest for the replacement of noble metal-based electrocatalysts for the efficient oxygen evolution reaction (OER) in an alkaline medium. Herein, a facile synthesis of NiO/delaminated boron composite and its electrocatalytic activity is reported. The influence of the loading level of delaminated boron on the electrocatalytic OER activity of NiO in 1 M KOH medium is investigated systematically. The linear voltammetry study reveals that all NiO/delaminated boron (NiO-B-_X) composites demonstrate a higher current density response as well as lower overpotential compared to NiO. The presence of the borophene in the composite could have resulted in the introduction of positive charge carriers on NiO, thereby improving the kinetics of the OER. Besides, the dispersion of the NiO particles onto the surface of delaminated boron is expected to mitigate the aggregation of NiO particles and expose a larger number of electrochemically active sites, consequently enhancing the overall OER performance. Evidently, NiO-B-_X electrocatalysts prepared with 10 mg of the borophene, (NiO-B-₁₀), demonstrate both the lowest overpotential at 10 mA cm⁻² of 1.61 V and Tafel slope of 61.25 mV dec⁻¹. It also exhibits extended stability over 8 h.

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