Search Results (681)

Inspired by natural porphyrin-containing enzymatic active sites, metalloporphyrins have become important platforms for oxygen reduction reaction (ORR) catalysis because of their well-defined structures and tunable coordination environments. Recently, breaking the N₄-coordination environment of cobalt porphyrins by inverting one pyrrolic unit to generate N₃C₁-site, i.e., N-confused porphyrin, has emerged as an effective strategy to promote their electro-catalyzing ORR capability. Herein, we reviewed recent progress in N-confused cobalt porphyrin in catalyzing ORR, with special emphasis on the influence of the catalyst’s architecture. We first summarized the general ORR mechanism on metalloporphyrins and the computational methods commonly used for mechanistic studies. Then, for comparison, the more common modification strategies like meso- and β-position substitution, axial coordination, and dinuclear design were reviewed for cobalt porphyrin-based catalysts. The main part reviewed the N-confused cobalt porphyrins with three different architectures, i.e., molecular, framework, and supported heterogeneous molecular form, highlighting their synthesis, characterization, electrocatalytic ORR behavior, and mechanistic interpretation from both experimental and theoretical perspectives. It summarizes the current understanding of why CoN₃C₁ systems outperform the original CoN₄ porphyrin systems. The architecture of catalysts was found to affect the selectivity and mechanisms of ORR, along with the discussion of pH. The effects of N-confused strategy were compared to other modification strategies. Finally, we proposed possible directions for integrated catalyst design and mechanism studies. Full article

This study investigates the morphological, compositional, and electrochemical properties of carbon materials derived from Pepsi (P) and Coca-Cola (CC) precursors, before and after chemical activation with ZnCl₂. Scanning electron microscopy revealed a lower density of surface cracks in non-activated hydrothermal carbon (NAHC) samples compared to activated carbons (ACs), indicating structural changes induced by the corrosive activation process. Particle size analysis showed an increase in average diameter after activation, particularly pronounced in CC-derived samples, which also exhibited a broader particle size distribution. Elemental mapping confirmed carbon as the dominant and homogeneously distributed element, while oxygen-containing functional groups decreased significantly after activation. Oxygen reduction reaction investigation demonstrated that all synthesized non-activated and activated samples are electrocatalytically active in alkaline solution. CC-NAHC demonstrated the lowest Tafel slope (99 mV dec⁻¹), while activated samples showed higher values, indicating slower kinetics and increased reaction limitations. Despite this, activated carbons—particularly CC-AC—displayed significantly higher diffusion-limited current densities (~−4.8 mA cm⁻² at 1600 rpm), suggesting improved mass transport and conductivity. Furthermore, electron transfer number (n) analysis indicated that P-NAHC and CC-AC follow a near four-electron ORR pathway (n ≈ 3.6–3.9). Full article

The chiral-induced spin selectivity (CISS) effect enables the spin-selective transport of electrons through chiral systems, linking handedness with spin polarization. This review provides a comprehensive examination of the emerging field of chiral electrocatalysis, detailing also the extensive experimental and theoretical endeavor conducted to gain a deeper understanding of the fundamental physical principles and mechanistic characteristics of this phenomenon. In particular, the CISS effect has garnered significant attention within the scientific community due to its potential for broad applicability across several fields, ranging from spintronics to biology. Among them, the prospective harnessing of the CISS effect into electrocatalytic processes offers an innovative strategy to improve the performance of energy conversion and storage technologies. This review deeply examines the practical applications of the CISS effect across different electrocatalytic reactions, with particular emphasis on its influence on the oxygen reduction reaction (ORR) and its critical role in energy conversion systems where the ORR reaction is a key process, such as in metal–air batteries, whose safety and performance can be enhanced through spin-selective electron transport. Full article

Effective regulation of the adsorption strength of oxygen reduction reaction (ORR) intermediates on active sites is the key to enhancing their catalytic performance. This study proposes an axial coordination modulation strategy by successfully anchoring the dioxin-linked FePcF₁₆-based covalent organic frameworks (COFs) onto amino-functionalized multi-walled carbon nanotubes (NH₂-MWCNTs), constructing a FePcF₁₆-COF/NH₂-MWCNT hybrid catalyst. Experimental results demonstrate that the catalyst exhibits outstanding ORR activity (E_1/2 = 0.901 V; J_L = 5.133 mA cm⁻²), outperforming commercial 20% Pt/C and most reported Fe-based non-precious metal catalysts. Furthermore, the robust dioxin-linked COF skeleton endows the catalyst with excellent electrochemical stability. A zinc–air battery using this catalyst as the cathode also demonstrates superior power density and cycling performance. This work provides a new strategy for designing highly efficient ORR catalysts through axial coordination environment engineering. Full article

Intermetallic compounds represent a highly promising class of materials for catalytic applications due to their tuneable structure, composition, and electronic properties. In this study, we report a series of carbon black-supported intermetallic Pt-Te and Pt-Zn nanoparticles synthesized via a novel and facile direct vapour–solid approach. Their catalytic performance toward the oxygen reduction reaction (ORR) in alkaline media was systematically investigated. Incorporation of Te or Zn into Pt/C significantly enhanced the intrinsic activity, as reflected by an increase in the limiting current density from −2.11 mA cm⁻² for Pt/C to up to −2.94 mA cm⁻² for Pt-Zn and −2.85 mA cm⁻² for Pt-Te systems, while maintaining similar half-wave potentials of 0.79 V vs. RHE and onset potentials around 0.90 V vs. RHE. This work provides a direct comparison of two intermetallic systems prepared under identical conditions, demonstrating how composition and crystal structure determine the catalytic activity and selectivity in the ORR. Full article

The cathodic oxygen reduction reaction (ORR) remains a major kinetic barrier to high-efficiency proton exchange membrane fuel cells (PEMFCs), motivating the search for electrocatalysts that combine high activity, low metal usage, and long-term durability. This review examines single-atom catalysts (SACs) as an emerging platform for fuel-cell cathodes with particular emphasis on how atomic-level design, ORR mechanism, and practical deployment barriers are interrelated. The review discusses the key ORR pathways, intermediate binding principles, and scaling constraints that govern cathodic performance, and examines how metal-center selection, coordination-environment engineering, support regulation, synergistic multi-site construction, and morphology-controlled synthesis can be used to tune intrinsic activity and stabilize isolated active sites. It further highlights mechanistic insights from theoretical and operando studies, with emphasis on structure–activity relationships, dynamic active-site evolution, and approaches to mitigate scaling limitations. Major barriers to practical deployment, including carbon corrosion, demetalization, agglomeration, peroxide/reactive oxygen species attack, and the persistent gap between half-cell metrics and membrane electrode assembly performance, are also critically assessed. Rather than treating these topics separately, this review discusses them as connected factors that together determine the viability of SAC-based fuel-cell cathodes. Full article

The efficient photocatalytic generation of hydrogen peroxide (H₂O₂) from pure water remains a formidable challenge, primarily due to the rapid recombination of photogenerated electron–hole pairs and insufficient redox potentials inherent in single-component photocatalysts. To address these issues, we designed and synthesized a heterojunction material comprising cadmium sulfide nanoparticles loaded on carbon spheres (CS@CdS). Under conditions utilizing pure water and ambient air, the CS@CdS composite achieves an H₂O₂ production rate of 1305 μmol·g⁻¹·h⁻¹, which is 3.1 and 3.6 times higher than that of pure CdS and CS, respectively, without the need for any sacrificial agents or external oxygen supply. Systematic characterization reveals that CS and CdS form a tightly coupled electronic interface, which significantly accelerates charge carrier separation and effectively prolongs the lifetime of photogenerated carriers, thereby boosting photocatalytic performance. Furthermore, the CS component extends the visible-light absorption range of the composite and functions as an electron acceptor to suppress charge recombination, collectively endowing CS@CdS with enhanced photocatalytic activity. Mechanistic studies indicate that H₂O₂ production over CS@CdS proceeds predominantly via a two-step single-electron oxygen reduction reaction (ORR) pathway. This work offers a viable strategy for constructing CS-based heterojunction photocatalysts for efficient H₂O₂ synthesis. Full article

Developing an ultrasensitive electrochemiluminescence (ECL) detection platform remains challenging due to the limited enrichment efficiency of ECL emitters and co-reactants at the electrode interface, as well as the insufficient catalytic enhancement of co-reactant conversion. Moreover, simultaneous in situ analyte enrichment and efficient anti-interference capability are often difficult to achieve in a single sensing interface. Herein, a new ECL platform was developed based on nanocatalyst-supported nanochannel-confined surfactant micelle (SM) system, which integrates an enhanced luminol-dissolved oxygen (DO) ECL response for the ultrasensitive detection of antibiotic rifampicin (RIF). A nanocomposite comprising nitrogen-doped graphene quantum dots and a molybdenum disulfide nanosheet (NGQDs@MoS₂) was modified on an indium tin oxide (ITO) electrode. This nanocomposite layer catalyzed the oxygen reduction reaction (ORR), boosting the co-reactant efficiency of DO. Vertically ordered mesoporous silica film filled with surfactant micelles (SM@VMSF) was subsequently grown in situ on the NGQDs@MoS₂ surface. The hydrophobic micelles enable the simultaneous enrichment of luminol, DO, and RIF. Integrating the triple-enrichment effect of surfactant micelles with the high electrocatalytic effect of NGQDs@MoS₂ nanocomposite results in significant ECL enhancement of the luminol–DO. SM@VMSF also provides an excellent molecular sieving effect, endowing the sensor with high anti-interference capability and stability. RIF quenches the ECL signal by consuming superoxide anion radicals, enabling sensitive detection. Detection of RIF was established with a high sensitivity (2927 a.u. per nM) wide linear range (10 pM to 10 μM) and a low limit of detection (LOD, 2.5 pM). The fabricated sensor exhibits good selectivity and high fabrication reproducibility (relative standard deviation, RSD, of 1.9%). Additionally, the determination of RIF in eye drops and seawater samples was realized. This work offers new insights for the design of high-performance ECL sensing interfaces and sensitive detection of RIF. Full article

Pt–transition metal intermetallic compounds have been recognized as promising catalysts for oxygen reduction reaction (ORR). However, further enhancing the activity and durability of this kind of catalyst is still necessary. Herein, we report a novel L1₀-type PtFe intermetallic nanoalloy with the partial substitution of Fe sites by La as a highly active and stable catalyst towards ORR. This new intermetallic nanoalloy retains an ordered structure after the incorporation of La confirmed by XRD, XPS and TEM results and the ordered PtFe_0.5La_0.5 nanoparticles are embedded in porous carbon (L1₀-PtFe_0.5La_0.5@C) in very uniform particle size of around 2 nm. This L1₀-PtFe_0.5La_0.5@C catalyst exhibits a half-wave potential of 933 mV, which is about 12 mV and 70 mV higher than those of L1₀-PtFe@C and commercial Pt/C catalysts, respectively. Moreover, it also achieves an enhanced mass activity of 0.79 A mg_Pt⁻¹ at 0.90 V, which outperforms the performance of commercial Pt/C (0.10 A mg_Pt⁻¹). In addition, it also shows excellent stability with only 3 mV negative shift in half-wave potential after 20k CV cycles of accelerated durability testing. This high activity and stability may be attributed to the incorporation of La in the PtFe lattice, which induces the formation of a compressively strained Pt overlayer in acidic media which not only tunes the surface strain of Pt sites but also possesses robust resistance to the dissolution of Fe and La. This work also provides a new direction for the development of Pt-based intermetallic catalysts for efficient catalysis applications. Full article

Electrocatalytic H₂O₂ production via the two-electron oxygen reduction reaction (ORR) is a highly sustainable alternative to industrial methods. To further optimize non-noble catalysts, we report an interfacial engineering strategy to stabilize the metastable P6₃/mmc-La₂O₃ phase on SrTiO₃. This symmetry evolution from the low-symmetry $\mathrm{P}\stackrel{\mathrm{-}}{3}\mathrm{m}1$ (trigonal) to the high-symmetry P6₃/mmc (hexagonal) space group yields a composite with >95% H₂O₂ selectivity. Mechanistic studies demonstrate that the symmetry-regulated interface optimizes *OOH conversion and suppresses O–O bond cleavage. This work offers a robust design principle for high-performance, noble-metal-free H₂O₂ electrosynthesis. Full article

Two-dimensional antimonene has recently emerged as a promising electrocatalytic platform; however, its oxygen reduction reaction (ORR) activity and modulation strategies remain largely unexplored. Herein, density functional theory (DFT) calculations are employed to systematically investigate ORR catalysis on antimonene co-doped with transition metal (TM) and nonmetal (C, P) dual atoms. The results reveal that Pd@C–Sb, Pt@C–Sb, and Pd@P–Sb exhibit remarkably enhanced ORR activity, delivering low overpotentials of 0.31 V, 0.32 V, and 0.38 V, respectively, significantly outperforming their single-atom-doped counterparts. Mechanistic analyses demonstrate that nonmetal dopants induce strong synergistic interactions with TM centers, leading to charge redistribution and effective regulation of the TM d-band center, which optimizes the adsorption energetics of key ORR intermediates. Notably, the number of d-electrons of TM atoms is identified as a reliable electronic descriptor governing intermediate binding strength and catalytic activity. Furthermore, ab initio molecular dynamics simulations confirm the excellent thermodynamic stability of the optimized dual-atom catalysts. This work elucidates the atomic-scale origin of synergistic enhancement in dual-atom-doped antimonene and provides a rational design strategy for high-performance ORR electrocatalysts based on two-dimensional main-group materials. Full article

Microbial fuel cells (MFCs) are a sustainable approach to wastewater treatment and energy recovery. However, their practical utility is often limited by sluggish cathode kinetics. For this technology, developing cost-effective biocatalysts that do not compromise effectiveness is a primary challenge. In this study, we utilized anthocyanin molecularly functionalized Escherichia coli (Cya-WT) to promote the formation of electroactive biofilms and regulate the intrinsic catalytic activity of single cells, thereby enhancing extracellular electron transfer. MFCs incorporating Cya-WT-loaded carbon cloth (CC) biocathodes were configured to simultaneously evaluate power generation and glucose degradation activity. The results indicated that Cya-WT exhibited significantly improved oxygen reduction reaction (ORR) activity, achieving a reduction peak current of 3.61 mA cm⁻², compared to 2.02 mA cm⁻² for wild-type E. coli (WT). The assembled MFC offers a peak power density of 268 ± 13.4 μW cm⁻² and decomposes 17.1 ± 1.15 mM of glucose in 150 h, maintaining a consistent voltage output for 800 h. These results demonstrate that anthocyanin functionalization significantly enhances the electrocatalytic performance and metabolic capabilities of E. coli. This novel catalyst design method offers a new strategy for low-cost, renewable MFC cathode catalysts and shows good promise in MFC biopower generation through the assembly of carbon-based biocathodes. Full article

It has long been recognized that the oxygen reduction reaction occurs more readily on Pt(111) surfaces that include steps, both (111) and (100), than on near-perfect Pt(111). Theoretical models were developed involving the water structure in the electric double layer and its interactions with adsorbed OH, with the actual O₂ reduction occurring on the (111) terraces adjacent to the steps. However, the present density functional theory (DFT) calculations confirms that O₂ adsorbs strongly at the steps and can undergo dissociation aided by adjacent water molecules to produce adsorbed OH. OH produced at the steps can move to the (111) terraces, where it can be more readily reduced to H₂O and desorbed. This model avoids the scaling relation, which predicts that all oxygen-containing reactants and intermediates are proportional to each other on any given surface, i.e., strong O₂ adsorption at steps compared with water ensures that the reaction can proceed. Efforts to develop new O₂ reduction catalysts have been hampered by the assumption that the reaction rate can be increased by decreasing OH adsorption strength, even though decreased OH adsorption strength is accompanied by decreased O₂ adsorption strength on any given crystallographic facet. This proposed model can explain the experimental results on stepped surfaces as well as nanoparticle catalysts, particularly the higher ORR activity on alloys such as PtFe, but with the obligatory presence of steps. The results may also be important for the development of Pt nanoparticle catalysts. Full article

Pt-based catalysts remain the most effective materials for the oxygen reduction reaction (ORR) at the cathode of proton exchange membrane fuel cells (PEMFCs); however, platinum scarcity and high cost severely limit the large-scale deployment of the technology. Improving catalytic activity and durability through precise control of nanoparticle morphology is therefore crucial for reducing costs and enhancing sustainability, enabling PEMFC widespread adoption. In this context, carbon-supported Pt-based nanoparticles with a 30 wt.% Pt loading were synthesized by an organometallic chemistry approach using hexadecylamine (HDA) as a stabilizer, allowing fine control over nanoparticle morphology. Two distinct synthesis pathways (one-pot and two-step procedures) were used to prepare platinum catalysts supported on KetjenBlack EC-300J (KB), and their influence on the electrocatalytic activity of the obtained nanomaterials was studied. Furthermore, the effect of HDA stabilization on catalyst performance was investigated. Directly synthesized Pt/KB catalysts exhibited similar ORR mass activity, regardless of whether or not HDA was present. Pt/KB prepared by the two-step procedure showed a significantly lower performance. Additionally, despite a larger loss of electrochemical surface area during an accelerated stress test compared to a commercial Pt/C reference, Pt^HDA/KB and Pt/KB catalysts maintained stable mass activity and limited specific activity degradation, highlighting the beneficial effect of nanoparticle stabilization in the presence of HDA on prolonged electrocatalyst cycling. Full article

Hollow nanostructures have emerged as a pivotal class of nanomaterials in electrocatalysis, offering intrinsic advantages such as high surface-to-volume ratios, reduced density, and economical utilization of precious metals. However, the prevailing research paradigm has predominantly focused on the external shell characteristics while overlooking the decisive role of the interior cavity microenvironment. This review introduces a novel conceptual framework that positions the rational engineering of the cavity microenvironment—encompassing mass transport dynamics, localized electronic structure modulation, active site exposure, and structural stability—as a unified design principle for next-generation electrocatalysts. We systematically elucidate how precise control over cavity geometry, composition, and interfacial properties can optimize electrocatalytic performance for oxygen reduction (ORR), oxygen evolution (OER), and hydrogen evolution (HER) reactions. By correlating microenvironmental parameters with catalytic metrics, we establish structure–property–performance relationships and highlight recent breakthroughs. Finally, we outline future challenges in achieving atomic-level precision in cavity design, understanding dynamic evolution under operating conditions, and scaling up synthesis for industrial applications. Full article