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The generation of above-bandgap photovoltage, referred to as the anomalous photovoltaic effect (APV), is an extraordinary characteristic sought after property in bulk ferroelectric photovoltaic devices. Despite the fact that the relatively narrow bandgap of BiFeO3 (BFO) (2.7 eV) induces a comparatively larger generation of photocurrent than other ferroelectric photovoltaic, it falls short in producing an anomalous photovoltage (Eg ≪ Voc) and exhibits leaky ferroelectric hysteresis due to unavoidable oxygen vacancies. This work revealed a reduction in oxygen vacancies through the substitution of Ba(Fe1/2Nb1/2)O3 in BFO, leading to improved structural, morphological, synchrotron XPS, and electrical properties. This reduction in oxygen vacancies has resulted in an impressive above-bandgap photovoltage (APV) of 4.41 V for 80BFO–20BFN with greater ferroelectric polarization (Pr = 20.45 μC/cm2) observed at the co-existence of polar and non-polar phases. Moreover, both theoretical and experimental optical analyses have demonstrated a significant decrease in the bandgap to 1.92 eV, effectively extending the visible region close to 653 nm. As a result, a larger population of photoexcited charge carriers is generated, enabling the attainment of a high current density (Jsc) of 0.75 μA/cm2 under 100 mW/cm2 light irradiation. [ABSTRACT FROM AUTHOR]

Very recently, open-cage metallo-azafullerenes PbC100N4H4 and Pb2C100N4H4 containing one Pb–N4–C moiety have been synthesized via the electron beam. Herein, we utilized density functional theory calculations in combination with ab initio molecular dynamics (AIMD) simulations to study the geometric and electronic structures, bonding properties, thermodynamic stability, and catalytic performance of MC100N4H4 and M2C100N4H4 (M = Ge, Sn, Pb). Metal–nitrogen distances and metal–metal distances increase along with the metal radius while the metal atom is positively charged. Energy decomposition analysis revealed that the bonding interactions between M and the C100N4H4 fragment could be described as the donor–acceptor interaction between M(ns0(n−1)d10np4) and C100N4H4 fragment, in which the orbital interactions terms contribute more than the electrostatic interactions. AIMD simulations demonstrate that those metallo-azafullerenes exhibit thermodynamic stability at room temperature. These metallo-azafullerenes, which could serve as typical carbon-supported single-atom catalysts, possess enhanced catalytic performance toward the oxygen reduction reaction (ORR) compared to the planar catalysts, which is attributed to the curvature of metallo-azafullerenes. GeC100N4H4 and SnC100N4H4 exhibit high catalytic performance in the 4e-ORR pathway to H2O, whereas only PbC100N4H4 is suitable for the 2e-ORR reaction pathway because of the difficulty in obtaining electrons. All M2C100N4H4 favors the 4e-reaction pathway due to the presence of the axial metal atom. Our finding of open-cage metallo-azafullerenes as efficient single-atom catalysts holds profound implications for both fundamental research in catalysis and practical applications in fuel cells and other electrochemical devices. [ABSTRACT FROM AUTHOR]

We report the free energy barriers for the elementary reactions in the 2e− and 4e− oxygen reduction reaction (ORR) steps on Au(100) in an alkaline solution. Due to the weak adsorption energy of O2 on Au(100), the barrier for the association channel is very low, and the 2e− pathway is clearly favored, while the barrier for the O–O dissociation channel is significantly higher at 0.5 eV. Above 0.7 V reversible hydrogen electrode (RHE), the association channel becomes thermodynamically unfavorable, which opens up the O–O dissociation channel, leading to the 4e− pathway. The low adsorption energy of oxygenated species on Au is now an advantage, and residue ORR current can be observed up to the 1.0–1.2 V region (RHE). In contrast, the O–O dissociation barrier on Au(111) is significantly higher, at close to 0.9 eV, due to coupling with surface reorganization, which explains the lower ORR activity on Au(111) than that on Au(100). In combination with the previously suggested outer sphere electron transfer to O2 for its initial adsorption, these results provide a consistent explanation for the features in the experimentally measured polarization curve for the alkaline ORR on Au(100) and demonstrate an ORR mechanism distinct from that on Pt(111). It also highlights the importance to consider the spin state of O2 in ORR and to understand the activation barriers, in addition to the adsorption energies, to account for the features observed in electrochemical measurements. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR), a pivotal process in hydrogen fuel cells crucial for enhancing fuel cell performance through suitable catalysts, remains a challenging aspect of development. This study explores the catalytic potential of germanene on Al (111), taking advantage of the successful preparation of stable reconstructed germanene layers on Al (111) and the excellent catalytic performance exhibited by germanium-based nanomaterials. Through first-principles calculations, we demonstrate that the O2 molecule can be effectively activated on both freestanding and supported germanene nanosheets, featuring kinetic barriers of 0.40 and 0.04 eV, respectively. The presence of the Al substrate not only significantly enhances the stability of the reconstructed germanene but also preserves its exceptional ORR catalytic performance. These theoretical findings offer crucial insights into the substrate-mediated modulation of germanene stability and catalytic efficiency, paving the way for the design of stable and efficient ORR catalysts for future applications. [ABSTRACT FROM AUTHOR]

Magnetic property (e.g. spin order) of support is of great importance in the rational design of heterogeneous catalysts. Herein, we have taken the Ni-supported ferromagnetic (FM) CrBr3 support (Nix/CrBr3) to thoroughly investigate the effect of spin-order on electrocatalytic oxygen reduction reaction (ORR) via spin-polarized density functional theory calculations. Specifically, Ni loading induces anti-FM coupling in Ni–Cr, leading to a transition from FM-to-ferrimagnetic (FIM) properties, while Ni–Ni metallic bonds create a robust FM direct exchange, benefiting the improvement of the phase transition temperature. Interestingly, with the increase in Ni loading, the easy magnetic axis changes from out-of-plane (2D-Heisenberg) to in-plane (2D-XY). The adsorption properties of Nix/CrBr3, involving O2 adsorption energy and configuration, are not governed by the d-band center but strongly correlate with magnetic anisotropy. It is noteworthy that the applied potential and electrolyte acidity triggers spin-order transition phenomena during the ORR and induces the catalytic pathway change from 4e− ORR to 2e− ORR with the excellent onset potential of 0.93 V/reversible hydrogen electrode, comparable to the existing most excellent noble-metal catalysts. Generally, these findings offer new avenues to understand and design heterogeneous catalysts with magnetic support. [ABSTRACT FROM AUTHOR]

In view of the inherent pseudocapacitance, rich redox pairs (Nb5+/Nb4+ and Nb4+/Nb3+), and high lithiation potential (1.0–3.0 V vs Li/Li+), Nb2O5 is considered a promising anode material. However, the inherent low electronic conductivity of Nb2O5 limits its lithium storage performance, and the rate performance after carbon modification is still unsatisfactory because the intrinsic conductivity of Nb2O5 has not been substantially improved. In this experiment, taking the improvement of the intrinsic electrical conductivity of Nb2O5 as the guiding ideology, we prepared F-doped Nb2O5@fluorocarbon composites (F–Nb2O5@FC) with a large number of oxygen vacancies by one-step annealing. As the anode electrode of lithium-ion batteries, the reversible specific capacity of F–Nb2O5@FC reaches 150 mA g−1 at 5 A g−1 after 1100 cycles, and the rate performance is particularly outstanding, with a capacity up to 130 mA g−1 at 16 A g−1, which is far superior to other Nb2O5@carbon-based anode electrodes. Compared with other single conductivity sources of Nb2O5@carbon-based composites, the electrical conductivity of F–Nb2O5@FC composites is greatly improved in many aspects, including the introduction of free electrons by F− doping, the generation of oxygen vacancies, and the provision of a three-dimensional conductive network by FC. Through analytical chemistry (work function, UV–Vis diffuse reflectance spectroscopy, and EIS) and theoretical calculations, it is proved that F–Nb2O5@FC has high electrical conductivity and realizes rapid electron transfer. [ABSTRACT FROM AUTHOR]

In this work, we have proposed a Continuous Constant Potential Model (CCPM) based on grand canonical density functional theory for describing the electrocatalytic thermodynamics on single atom electrocatalysts dispersed on graphene support. The linearly potential-dependent capacitance is introduced to account for the net charge variation of the electrode surface and to evaluate the free energetics. We have chosen the CO2 electro-reduction reaction on single-copper atom catalysts, dispersed by nitrogen-doped graphene [CuNX@Gra (X = 2, 4)], as an example to show how our model can predict the potential-dependent free energetics. We have demonstrated that the net charges of both catalyst models are quadratically correlated with the applied potentials and, thus, the quantum capacitance is linearly dependent on the applied potentials, which allows us to continuously quantify the potential effect on the free energetics during the carbon dioxide reduction reaction instead of confining it to a specific potential. On the CuN4@Gra model, it is suggested that CO2 adsorption, coupled with an electron transfer, is a potential determining step that is energetically unfavorable even under high overpotentials. Interestingly, the hydrogen adsorption on CuN4@Gra is extremely easy to occur at both the Cu and N sites, which probably results in the reconstruction of the CuN4@Gra catalyst, as reported by many experimental observations. On CuN2@Gra, the CO2RR is found to exhibit a higher activity at the adjacent C site, and the potential determining step is shifted to the *CO formation step at a wide potential range. In general, CCPM provides a simple method for studying the free energetics for the electrocatalytic reactions under constant potential. [ABSTRACT FROM AUTHOR]

The development of highly active and stable iron–nitrogen (Fe–Nx) based oxygen reduction reaction (ORR) catalysts with pH versatility is one of the future directions of electrochemical energy. However, the task of designing and controlling the three-dimensional local structure of Fe species to obtain high ORR activity and stability remains a challenge. In this study, we prepared hierarchical porous FeN–hcC (iron–nitrogen–highly curved carbon) catalysts derived from ZIF-L by a soft template method. The highly curved carbon surface possibly results in a compressive strain effect on the supported Fe–Nx active site, which can not only enhance the high exposure of the active site to improve the electrocatalytic activity, but also facilitate the stability of the Fe–Nx site during the ORR catalytic process. FeN–hcC-1 exhibited a high half-wave potential of 0.89, 0.77 and 0.82 V vs. RHE in alkaline, acidic, and neutral media, respectively. In addition, after cyclic durability tests in different electrolyte environments, good stability is still maintained, which is significantly better than the planar Fe–Nx site and Pt/C catalyst. This work provides a new synthetic strategy for the construction of highly curved surfaces of carbon materials, while inspiring a method to improve the ORR performance of ZIF-derived materials. [ABSTRACT FROM AUTHOR]

The electrocatalytic urea oxidation reaction (UOR) can serve as an alternative to the anodic oxygen evolution reaction (OER) in water splitting. Therefore, it is of great significance to develop efficient and cheap electrocatalysts to improve the kinetics of the UOR. In this study, a Ni/NiO/NiB@NC-500 composite was prepared by anchoring Ni/NiO/NiB nanoparticles on a nitrogen-doped carbon substrate through a straightforward hydrothermal-pyrolysis method. The optimal Ni/NiO/NiB@NC-500 composite exhibited remarkable activity and stability for the UOR, that is, the current density (j) of Ni/NiO/NiB@NC-500 for the UOR was 264 mA cm−2 at a potential of 1.67 V. Furthermore, the j retention rate of Ni/NiO/NiB@NC-500 was 84.6% of the initial value after 12 h of chronoamperometry (CA) test. The remarkable performance of Ni/NiO/NiB@NC-500 was ascribed to the following aspects: its hydrophilicity facilitated the adsorption of reactants and products, its porous spongy structure exposed more active sites for the UOR and promoted charge transfer and electrolyte diffusion, and the nitrogen-containing carbon matrix enhanced its electrical conductivity and stability. In addition, the density functional theory (DFT) calculations indicated that the introduction of B significantly reduced the energy barrier of the rate-determining step (RDS) during the UOR. [ABSTRACT FROM AUTHOR]

The document from Chemical Communications, published in 2024, provides a comprehensive list of articles covering various topics in chemistry. The articles include discussions on functional metal-organic frameworks for energy storage, bioinspired hydrogels for artificial photosynthesis, and catalytic applications of organic-inorganic hybrid materials. The journal aims to connect the global chemistry community and reinvest profits back into the field. [Extracted from the article]

Here, we propose a sub-3 nm small-size PtCo alloy catalyst integrated into a porous nitrogen-doped nanosheet through a space-confined and interfacial induction strategy. The designed PtCo–CoNC–P catalyst exhibits exceptional durability, with only a minimal 2 mV decline in half-wave potential after 30 000 cycles of accelerated durability tests. [ABSTRACT FROM AUTHOR]

Non-precious metal catalysts (NPMCs) doped with nitrogen were derived from MOFs. Appropriate ligand and framework order in the precursor ensured the presence of various nitrogenous species and high surface area in the NPC, Ni-NPC, Co-NPC, and Fe-NPC electrocatalysts. Electrochemical properties of the as-prepared electrocatalysts were examined in 0.1 M KOH solution to investigate the effects of metal and doped nitrogen on the oxygen reduction reaction (ORR). The free metal electrocatalyst (NPC) displayed poor ORR activity with an onset potential of 0.87 V RHE. The presence of nickel in the Ni-NPC catalyst could not create more active sites in comparison with the NPC catalyst, while onset potential of the Co-NPC catalyst shifted to 21 mV more positive (Compare to NPC). The investigation of doping active transient metals indicated that Fe-doping could be effective. It was because of the improved ORR activity of the Fe-NPC electrocatalysts with an onset potential of 0.99 V RHE. Furthermore, in a long-term stability test, this optimum electrocatalyst could retain more than 92% of its initial current density and experienced just 57 mV loss in its half-wave potential in an accelerated degradation test. Direct ethanol fuel cell test reveals maximum power density of 19.2 mW cm−2 at ambient temperature. • New M-NPS electrocatalysts were synthesized by pyrolysis of effective MOF precursors. • The synthesized M-N-C electrocatalysts had high surface area and a variety in nitrogenous species. • The effect of the metal on the activity and stability of the M-N-C electrocatalysts was evaluated for ORR. • The sequence of the catalysts activity in ORR are: FeN x > CoN x > NiN x ∼ metal free-N x. [ABSTRACT FROM AUTHOR]

The development of high active and stable cathode materials is one of the main challenges of intermediate temperature solid oxide fuel cells (SOFCs). Herein, a high-entropy Fe-based perovskite oxide La 0.7 Sr 0.3 Fe 0.3 Ni 0.3 Co 0.3 Mo 0.1 O 3-δ (LSFNCM) is synthesized by self-propagation combustion based on La 0.7 Sr 0.3 FeO 3-δ (LSF) and the electrochemical properties are systematically tested. The symmetric half-cell with the LSFNCM cathode has a high catalytic activity with a polarization impedance of 0.12 Ω cm2 at 800 °C, and also shows outstanding CO 2 resistance and chromium resistance owing to the entropy stabilization strategy. After 50h of treatment in a 10% CO 2 environment, the polarization impedance of the LSF electrode increases by 8.89 Ω cm2, while that of the LSFNCM electrode only increases by 1.81 Ω cm2. Additionally, after being treated for 24h in a chromium vapor environment, the polarization impedance of the LSF electrode increases by 5.95 Ω cm2, whereas that of the LSFNCM electrode only increases by 0.44 Ω cm2. Moreover, the single cell with LSFNCM cathode exhibits the maximum power density of 932.82 mW/cm2 and the polarization impedance of 0.34 Ω cm2 at 800 °C with humidify hydrogen as fuel. Our results indicate that high-entropy perovskite oxide LSFNCM is an active and Cr-tolerant promising cathode for SOFCs. • LSFNCM has excellent oxygen reduction reactivity. • LSFNCM exhibits excellent stability in a 10% CO 2 atmosphere. • The process of oxygen reduction is further understood by distribution of relaxation time analysis. • LSFNCM shows excellent stability in chromium-containing environments. [ABSTRACT FROM AUTHOR]

Developing cost-effective and high-performing bifunctional electrocatalysts is pivotal for advancing rechargeable zinc-air batteries (ZABs). In this study, a Pd–Co₃O₄ loaded on acetylene black (Pd–Co₃O₄/C) electrocatalyst was developed with excellent properties for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) using reduced H₂PdCl₄ to modify Co₃O₄/C. The experimental findings indicate that the Pd–Co₃O₄/C electrocatalyst exhibits a favorable half-wave potential for ORR at 0.91 V, a feasible potential for OER at 1.48 V (measured at 10 mA/cm2), also minor Tafel slopes for both ORR (44.65 mV/dec) and OER (58.41 mV/dec). Additionally, it evidences a power density of 186 mW/cm2 in ZABs and good durability during galvanostatic charge-discharge cycling. The impressive performance of Pd–Co₃O₄/C can be ascribed primarily to the beneficial synergistic effect resulting from the composition of Co₃O₄ and Pd embedded within graphite carbon. This research lays the groundwork for the expansion of additional cost-effective and highly effective electrocatalysts in the coming years. [Display omitted] • Pd-Co₃O₄/C as a bifunctional oxygen electrocatalyst was developed. • Pd-Co₃O₄/C achieves 1.02 V onset potential vs. RHE and 290 mV overpotential at 10 mA/cm² current density. • Pd-Co₃O₄/C shows exceptional cyclic stability at high current density due to high electron transfer and synergistic effects. [ABSTRACT FROM AUTHOR]

Low intrinsic electrocatalytic activity and inferior conductivity limit the application of Ni/NC in acidic electrocatalytic hydrogen evolution reaction (HER). Herein, we prepared nitrogen-doped carbon nanosheet confined PtNi alloy electrocatalysts (PtNi/NC-10) using PtCl 6 2− electrostatic adsorption coupling melamine pyrolysis nitriding strategy. PtNi alloying was confirmed by the crystallinity decrease and lattice expansion of Ni/NC. The alloying and confinement effect of Metal-Organic Frameworks (MOFs) suppresses the oxidation and agglomeration of metal nanoparticles during pyrolysis, thus significantly reducing particle size, increasing specific surface area, and promoting the exposure of active sites. The strong electronic interaction between Pt and Ni optimizeds the surface charge distribution, enhancing the adsorption of H species on electron-rich Pt sites, thereby improving reaction kinetics. In addition, PtNi alloying improves the conductivity of the material, accelerating charge transfer and proton transport. Consequently, the prepared PtNi/NC-10 exhibits superior HER performance than Ni/NC in 0.5 M H 2 SO 4 solution, even comparable to commercial 20 wt % Pt/C, with the overpotentials of 35 mV at 0.01 A cm−2. Furthermore, the electrocatalysts assembled PtNi/NC-10-CP‖RuO 2 -TFF proton exchange membrane (PEM) electrolyzer only requires 2.32 V cell voltage to achieve 1 A cm−2, presenting practical application prospects. Our work provides a novel idea for designing efficient and stable MOFs confined to alloy-based HER electrocatalysts. [Display omitted] • PtNi alloying reduces nanoparticle size and promotes active site exposure. • Surface charge distribution of Pt and Ni sites optimizes reaction kinetics. • Pt introduction enhances conductivity and accelerates surface charge exchange. [ABSTRACT FROM AUTHOR]

Porous one-dimensional Pt-based alloys with outstanding specific surface areas, short electron transport paths, and accessible Pt atoms are potential electrocatalysts for methanol oxidation reaction (MOR); however, their simple one-step synthesis for MOR remains a challenge. In this study, a simple one-step method is presented for the rational fabrication of PtPb porous nanowires (PNWs) by the direct autoclave of binary metal precursors in the mixed solvent of ethylene glycol and N,N -dimethylformamide at 170 °C. The formation of PtPb PNWs is driven by the autocatalytic and Ostwald ripening growth mechanism with the assistance of ethylene glycol and N,N -dimethylformamide as a solvent, in situ template, and reducing agent. This method forms PtPb porous ultra-long (∼1.5 μm) neural PNWs with an average width of 20 nm enriched with abundant pores (5–10 nm), high Pb content (29 wt%), and decreased d-band level of Pt. These unique structural features enhanced the MOR mass (specific) activity of PtPb PNWs of 4.39 mA/μg Pt (49.3 mA/cm2) by 4.5 (9.6) and 5.5 (35.0) times than those of Pt PNWs and Pt/C catalyst, respectively besides higher durability and CO-tolerance. The MOR activity of PtPb PNWs was among the highest reported binary porous Pt-based catalysts, which may promote the preparation of other Pt alloys PNWs for MOR. [Display omitted] • Porous PtPb neural nanowires (PNWs) were prepared by a simple one-step method. • The formation mechanism of PtPb PNWs was underlined using various analyses. • The methanol oxidation performance of PtPb PNWs was superior to other PtPb. • The mass activity of PtPb PNWs was higher than Pt PNWs and Pt/C catalysts. [ABSTRACT FROM AUTHOR]

The cathodic catalytic activity for the oxygen reduction reaction (ORR) plays a critical role in determining the performance of proton-conducting solid oxide fuel cells (P-SOFCs). BaCo 0.4 Fe 0.4 Zr 0.2 O 3-δ (BCFZ) has emerged as a promising cathode for P-SOFCs due to its triple-phase conductivity. Nevertheless, its suboptimal proton conductivity and hydration ability at intermediate temperatures prevent it from achieving the anticipated ORR catalytic activity. To address these limitations, this study explores the enhancement of electrocatalytic activity in BCFZ through alkali metal doping and A-site defect construction. The effects of such modifications on oxygen surface exchange kinetics and ORR catalytic activity are systematically investigated. The findings reveal that BCFZ exhibits relatively low parameters in terms of electronic conductivity, oxygen ion conductivity, oxygen vacancy concentration, k chem , and D chem. Conversely, these parameters are markedly improved in A-site deficient BCFZ (D-BCFZ) and Na/K-doped BCFZ. Consequently, the enhancement of these properties yields a significant increase in ORR catalytic activity, with D-BCFZ demonstrating the best electrochemical performance. Specifically, P-SOFC with D-BCFZ cathode achieves an R p value of just 0.073 Ω cm2 and a P max value of 0.928 W cm−2 at 650 °C. This study provides theoretical insight into the mechanisms by how alkali metal doping and defect construction enhance the ORR catalytic activity of BCFZ. These findings offer valuable guidance for the development and optimization of high-performance P-SOFC cathodes. [ABSTRACT FROM AUTHOR]

Improving proton transfer is vital for electrocatalysis with porous materials. Although several strategies are reported to assist proton transfer in channels, few studies are dedicated to improving proton transfer at the local environments of active sites in porous materials. Herein, we report on new Co‐corrole‐based porous organic polymers (POPs) with improved proton transfer for electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). By tuning the pore sizes and installing proton relays at Co corrole sites, we designed and synthesized POP‐2‐OH with improved proton transfer both in channels and at local Co active sites. This POP shows remarkable activity for both electrocatalytic ORR with E1/2=0.91 V vs RHE and OER with η10=255 mV. Therefore, this work is significant to present a strategy to improve active site local proton transfer in porous materials and highlight the key role of such structural functionalization in boosting oxygen electrocatalysis. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells (PCFCs), which are based on proton conducting electrolytes, are a class of power generation devices that can efficiently operate at the intermediate (500–700 °C), even low (450 °C) temperatures, but their development is hindered by sluggish cathodic kinetics at reduced temperatures. At the PCFC cathode, the absorbed oxygen molecules react with oxygen vacancies, protons and electrons to generate water and release electrical energy. Thus, the PCFC cathode materials require percolation network for proton, oxide-ion, and electron carriers simultaneously. In this work, we developed a triple ionic-electronic conductor BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ as a new cathode material for the PCFCs using BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ as the electrolyte. Anode supported cells were fabricated and the performances were investigated. Compared with the parent oxide, tungsten doping can significantly improve the electrochemical reduction kinetic of oxygen. The BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ based PCFC obtained the peak power density of 688 mW ⋅ cm−2 at 600 °C, which is 1.29 time higher than that of BaCo 0.4 Fe 0.4 Zr 0.2 O 3-δ based PCFC (the peak power density of 534 mW ⋅ cm−2 at 600 °C). Moreover, BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ has a better thermal expansion matching with the electrolyte material BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we develop an in situ biomass-confined approach to fabricate an atomically dispersed Fe/NC catalyst for ORR. The acquired Fe/NC demonstrates glorious oxygen reduction reaction (ORR) activity (E1/2: 0.858 V) in alkaline media and long-term cycling stability (∼750 h) in a homemade liquid zinc-air battery. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have emerged as promising platforms for the construction of single-atom and dual-atom catalysts (SACs and DACs), owing to their well-defined structures, tunable pore sizes, and abundant active sites. In recent years, the development of COF-based SACs and DACs as highly efficient catalysts has witnessed a remarkable surge. The synergistic interplay between the metal active sites and the COF has established the design and fabrication of COF-based SACs and DACs as a prominent research area in electrocatalysis. These catalytic materials exhibit promising prospects for applications in energy storage and conversion devices. This review summarizes recent advances in the design, synthesis, and applications of COF-based SACs and DACs for oxygen catalysis. The catalytic mechanisms of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are comprehensively explored, providing a comparative analysis to elucidate the correlation between the structure and performance, as well as their functional attributes in battery devices. This review highlights a promising approach for future research, emphasizing the necessity of rational design, breakthroughs, and in-situ characterization to further advance the development of high-performance COF-based SACs and DACs for sustainable energy applications. [ABSTRACT FROM AUTHOR]

Photocatalytic technology is considered to be a sustainable strategy to convert H2 O and O2 into H2 O2. However, constructing photocatalytically active and stable organic photocatalyst remain a challenge. In this study, a new class of porous aromatic framework photocatalysts (BF-PAFs) were designed and synthesized, in which 9,9′-bifluorenylidene (99′-BF) and different alkynes are alternately connected. The BF-PAFs were constructed and served as photocatalysts for H2 O2 synthesis. Experimental results show that the introduction of different alkynes can effectively regulate the optical band gap and energy band structure, which may further determine their photocatalytic performance. Upon visible light irradiation, PAF-370 exhibits high efficiency for photosynthesis of H2 O2 with a production rate of 730 μmol g–1 h–1 in the presence of sacrificial reagent from water and oxygen via oxygen reduction reaction (ORR) pathway. Furthermore, up to 61 μmol H2 O2 could be generated from this photocatalytic system after 14 hours. [ABSTRACT FROM AUTHOR]

The electrochemical production of hydrogen peroxide through the oxygen reduction reaction (ORR) presents the interesting situation where the fully reduced form, H2O, is significantly favored by thermodynamics. Perovskite oxide based catalysts with slow kinetics, or large overpotentials, have been shown to enable production of H2O2 with good selectivity, but this comes at the expense of energy efficiency and production rates. We analyze the structure and electrocatalytic ORR capabilities of a perovskite oxide series based on LaCr1‐xCoxO3. We find that the crystal lattice distorts in two ways as Co content increases – anisotropic compression of the lattice is accompanied by a pinching of angles within the structure, which gives way to compression of B−O bonds at higher Co contents. Product selectivity is observed to change as a function of both catalyst composition and rotation rates of rotating ring‐disk electrode. The rotation‐dependent behavior is attributed to accelerated displacement of surface‐bound peroxide intermediates by a pH gradient at the catalyst surface, and composition‐dependent changes in selectivity are found to correlate to the angular distortion of the crystal lattice. These results highlight the importance of local environments in electrocatalyst reactions and demonstrate that structure and local pH can be used to manipulate product selectivity. [ABSTRACT FROM AUTHOR]

Direct seawater zinc‐air batteries (S‐ZABs), with their inherent properties of high energy density, intrinsic safety, and low cost, present a compelling avenue for the development of energy storage technology. However, the presence of chloride ions in seawater poses challenges to their air electrode, resulting in sluggish reaction kinetics and poor stability for the oxygen reduction reaction (ORR). Herein, Fe atomic clusters (ACs) decorated Fe single‐metal atoms (SAs) catalyst (FeSA‐FeAC/NC) is prepared using a plasma treatment strategy. The aberration‐corrected transmission electron microscope images confirm the successful construction of Fe SAs surrounding Fe ACs, which delivers robust ORR activity with a half‐wave potential of 0.886 V in alkaline seawater electrolyte. When utilized as the cathode catalyst in assembled S‐ZABs, the battery demonstrates excellent discharge performance, achieving a peak power density of 222 mW cm−2, which is 2.3 times higher than Pt/C based S‐ZABs. Moreover, density functional theory calculations unveil that the synergy effect between the Fe ACs and SAs not only reduces the spin‐down d‐band center in the Fe SAs, but also efficiently suppresses Cl−1 adsorption on Fe SAs due to their strong Cl−1 absorption ability of the Fe ACs, thereby enhancing both the activity and stability of the catalyst. [ABSTRACT FROM AUTHOR]

Hydrogen‐terminated 2D–Germanane (2D–GeH), a germanium‐based 2D material akin to graphene, is receiving enormous attention owing to its predicted optoelectronic characteristics. However, experimental research of 2D–GeH is still in an early stage, and therefore its real implementation for task‐specific applications will depend on the correct development of suitable chemical functionalization methods. Herein, a general and straightforward organometallic (OM) approach is provided for the robust functionalization of 2D–GeH with different 0D noble metal nanoparticles (M–NPs), resulting in 0D/2D M@GeH nanoarchitectonics. As a proof‐of‐principle, 0D/2D Pt@GeH and Au@GeH nanoarchitectonics have been successfully synthesized, characterized, and explored as unconventional electrocatalysts for boosting energy conversion reactions. While the hydrogen evolution reaction activity was evaluated for Pt@GeH, the oxygen reduction reaction was interrogated for Au@GeH. Interestingly, the implanted catalytic features of M–NPs yielded to 0D/2D M@GeH nanoarchitectonics with enhanced energy conversion activity comparing to pristine 2D–GeH counterpart. This work proves the suitability of 2D–GeH as unconventional substrates to stabilize nobleM−NPs, and the versatility of the OM approach for the custom design of a new family of 0D/2D M@GeH nanoarchitectonics to expand the implementation of monoelemental 2D materials as promising electrocatalysts in energy conversion field and beyond. [ABSTRACT FROM AUTHOR]

Electrochemical synthesis of hydrogen peroxide (H2O2) via the two‐electron oxygen reduction reaction (2e−‐ORR) provides an alternative method to the energy‐intensive anthraquinone method. Metal macrocycles with precise coordination are widely used for 2e−‐ORR electrocatalysis, but they have to be commonly loaded on conductive substrates, thus exposing a large number of 2e−‐ORR‐inactive sites that result in poor H2O2 production rate and efficiency. Herein, guided by first‐principle predictions, a substrate‐free and two‐dimensional conductive metal–organic framework (Ni‐TCPP(Co)), composed of CoN4 sites in porphine(Co) centers and Ni2O8 nodes, is designed as a multi‐site catalyst for H2O2 electrosynthesis. The approperiate distance between the CoN4 and Ni2O8 sites in Ni‐TCPP(Co) weakens the electron transfer between them, thus ensuring their inherent activities and creating high‐density active sites. Meanwhile, the intrinsic electronic conductivity and porosity of Ni‐TCPP(Co) further facilitate rapid reaction kinetics. Therefore, outstanding 2e−‐ORR electrocatalytic performance has been achieved in both alkaline and neutral electrolytes (>90 %/85 % H2O2 selectivity within 0–0.8 V vs. RHE and >18.2/18.0 mol g−1 h−1 H2O2 yield under alkaline/neutral conditions), with confirmed feasibility for water purification and disinfection applications. This strategy thus provides a new avenue for designing catalysts with precise coordination and high‐density active sites, promoting high‐efficiency electrosynthesis of H2O2 and beyond. [ABSTRACT FROM AUTHOR]

Ammonia-oxidizing archaea (AOA) are key players in the nitrogen cycle and among the most abundant microorganisms in the ocean, thriving even in oxygen-depleted ecosystems. AOA produce the greenhouse gas nitrous oxide (N2O) as a byproduct of ammonia oxidation. Additionally, the recent discovery of a nitric oxide dismutation pathway in the AOA isolate Nitrosopumilus maritimus points toward other N2O production and consumption pathways in AOA. AOA that perform NO dismutation when exposed to oxygen depletion, produce oxygen and dinitrogen as final products. Based on the transient accumulation of N2O coupled with oxygen accumulation, N2O has been proposed as an intermediate in this novel archaeal pathway. In this study, we spiked N2O to oxygen-depleted incubations with pure cultures of two marine AOA isolates that were performing NO dismutation. By using combinations of N compounds with different isotopic signatures (15NO2− pool +44N2O spike and 14NO2− pool +46N2O spike), we evaluated the N2O spike effects on the production of oxygen and the isotopic signature of N2 and N2O. The experiments confirmed that N2O is an intermediate in NO dismutation by AOA, distinguishing it from similar pathways in other microbial clades. Furthermore, we showed that AOA rapidly reduce high concentrations of spiked N2O to N2. These findings advance our understanding of microbial N2O production and consumption in oxygen-depleted settings and highlight AOA as potentially important key players in N2O turnover. [ABSTRACT FROM AUTHOR]

Zinc-air batteries (ZABs) have received considerable interest because of the growing demand for high-energy–density and safe energy storage systems. Efficient and economical catalysts for the cathodic oxygen reduction reaction (ORR) in ZABs play a crucial role in reducing expenses and facilitating industrialization. In this study, an efficient alkaline ORR electrocatalyst derived from ZIF-67 is synthesized by a simple one-pot method followed by high-temperature calcination. The optimized catalyst, CoCu-NPC-1000, demonstrates outstanding electrocatalytic performance in ORR, with a half-wave potential (E1/2) of 0.849 V and an onset potential (Eonset) of 0.988 V. Notably, CoCu-NPC-1000 also shows excellent methanol tolerance, stability, and durability under alkaline conditions. These superior catalytic properties are attributed to the synergistic effect of Co-Nx and Cu-Nx dual active sites, along with the increased average pore diameter facilitated by the pore-forming agent Zn(NO3)2·6H2O. The CoCu-NPC-1000-based zinc-air battery outperforms the power density of Pt/C, achieving 107.1 mW cm⁻2 at a current density of 124.3 mA cm⁻2, compared to 84.79 mW cm⁻2 at 143 mA cm⁻2 for Pt/C. Additionally, its specific capacity reaches 851 mAh g Zn - 1 , exceeding that of Pt/C (688 mAh g Zn - 1 ). This study not only confirms the effectiveness of Zn(NO3)2·6H2O as a pore-forming agent but also offers valuable insights into synthesizing bimetallic organic framework-derived electrocatalysts for ZABs. [ABSTRACT FROM AUTHOR]

Among various strategies to enhance electrocatalytic activity, nanoporous structured electrodes have been widely utilized owing to their improved performance. Along with enlarged electrode surface, modified crystalline facets, and surface defects of nanoporous electrodes, recent studies have reported their unique electrocatalytic characteristics originating from the nanoconfined space, denoted as the nanoconfinement effect. Introducing nanoporous electrodes with controllable thickness made of indium tin oxide, an electrochemically inert material, has provided an optimal platform for analyzing the contribution of nanoporous structures to the catalytic effects. Nevertheless, the scope of reactants that has been studied based on this system so far is mostly limited to ferric/ferrous redox species in sulfate anion environment. Here, using the nanoporous indium tin oxide electrodes, we demonstrate the nanoconfinement effect toward the ferric/ferrous reaction in a different chemical environment that alters its electrokinetic characteristics compared to the previous studies. Furthermore, a complex multi‐electron transfer reaction of oxygen reduction is employed to explore the effects of nanoporous structure toward inner‐sphere reactions. Our work suggests that the nanoconfinement effects can be applied to a wider range of electrochemical reactions taking place in nanoporous electrodes. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Single‐atom catalysts (SACs) have attracted significant attention due to their high atomic utilization and tunable coordination environment. However, the catalytic mechanisms related to the active center and coordination environment remain unclear. In this study, we systematically investigated the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic activities of NiN4, NiN3, NiN3H2, NiN4X, NiN3X, and NiN3H2X (X denotes axial ligand) through density functional theory (DFT) calculations. This study unveils two distinct reaction pathways for ORR and OER, involving proton‐electron pairs adsorbed from both the solution and the catalyst surface. The overpotential is the key parameter to evaluate the catalytic performance when proton‐electron pairs are adsorbed from the solution. NiN3 and NiN3H2 show promise as pH‐universal bifunctional electrocatalysts for both ORR and OER. On the other hand, when proton‐electron pairs are adsorbed from the catalyst surface, the reaction energy barrier becomes the crucial metric for assessing catalytic activity. Our investigation reveals that NiN3H2 consistently exhibits optimal ORR activity across a wide pH range, regardless of the source of proton‐electron pair (solvent or catalyst surface). [ABSTRACT FROM AUTHOR]

Overcoming the trade‐off between the graphitization of the carbon substrate and enhanced electronic metal–support interaction (EMSI) and intrinsic activity of Pt‐C catalysts remains a major challenge for ensuring the durable operation of energy conversion devices. This article presents a hybrid catalyst consisting of PtFe nanoparticles and single Pt and Fe atoms supported on N‐doped carbon (PtFeNPs@PtFeSAs‐N‐C), which exhibits improved activities in hydrogen evolution and oxygen reduction reactions (HER and ORR, respectively) and has excellent durability owing to the high graphitization, rich edge defects, and porosity of the carbon in PtFeNPs@PtFeSAs‐N‐C, as well as strong EMSI between the PtFe nanoparticles and edge‐defective carbon embedded with Pt and Fe atoms. According to theoretical calculations, the strong EMSI optimizes the H* adsorption–desorption and facilitates the adsorption OOH*, accelerating the HER and ORR processes. A novel flow seawater‐Al/acid hybrid fuel cell using the PtFeNPs@PtFeSAs‐N‐C cathode can serve as a high‐efficiency energy conversion device that delivers a high power density of 109.5 mW cm−2 while producing H2 at a significantly high rate of 271.6 L m−2 h−1. Moreover, PtFeNPs@PtFeSAs‐N‐C exhibits a remarkable performance (high power density of 298.0 mW cm−2 and long‐term durability of 1000 h) in a flow Zn–air battery. [ABSTRACT FROM AUTHOR]

Metal‐coordinated N‐doped carbon (M‐N‐C) materials with highly curved structures have become a promising class of electrocatalysts for the oxygen reduction reaction (ORR). However, the stability of these electrocatalysts remains a problem due to the traditional post‐metal loading strategy. Herein, single‐atomic Co‐N‐C active sites anchored on helical carbonaceous nanotubes (HCNTs) are prepared (Co‐N‐C@HCNT) by pyrolyzing Co porphyrins and helical polypyrroles (PPys) mixtures at high‐temperature by one‐step method. Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) and X‐ray absorption fine structure (XAFS) measurements confirm single‐atomic active sites and Co‐N4 coordination structures of Co‐N‐C@HCNT. The optimized Co‐N‐C@HCNT exhibits excellent catalytic ORR activity with a half‐wave potential (E1/2) of 0.86 V versus reversible hydrogen electrode (vs RHE) compared to Co‐N‐C@CNT without helical structures (E1/2 = 0.81 V vs RHE) measured in 0.1 m KOH. Co‐N‐C@HCNT also displays excellent stability with a slight current decrease (4%) after running for 10 h featuring Co‐N4 active sites tightly anchored on HCNTs due to electrostatic interactions between metal porphyrins and PPys. Theoretical calculations indicate that the curved structure can increase the charge and decrease d‐band center at Co active site, which enhances electrocatalytic activity. This work provides a simple but effective strategy to construct helical M‐N‐C materials. [ABSTRACT FROM AUTHOR]

Recently, Pt‐free and highly efficient, nanostructured M–N–C catalysts employing earth‐abundant metals (M = Fe, Co, Ni, Mn, Cu, etc.) have been recognized as a very promising alternative to noble metal (in particular platinum)‐ based oxygen reduction reaction materials. Structural engineering of the M–N–C catalysts is expected to further boost their catalytic performance, and thus, intense efforts are currently ongoing. Herein, a report is prepared on X‐ray absorption fine structure (EXAFS) studies of different carbon‐based catalyst materials. EXAFS with its intrinsic sensitivity toward the local atomic arrangement around the X‐ray absorbing element allows to characterize isolated, active single‐atom transition metal centers and their atomic environments. In the case of Co and Fe, the analysis suggests in particular asymmetric, penta‐coordinated Co‐N5 and dual‐coordinated Fe–N–P sites. In both cases, a symmetric environment of the metals with only four nitrogen atoms appears to be unfavorable for the catalytic activity. In addition, for Fe–N4 centers embedded in a graphene host matrix, the EXAFS analysis allows to precisely determine the atomic arrangement around the iron atom, and thereby the geometry of the catalytic site. A discussion will be done on how EXAFS investigations can support the further development of single‐atom catalysts. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Dalton Transactions: An International Journal of Inorganic Chemistry," published by The Royal Society of Chemistry. It includes articles on various topics such as electrochemically driven physical properties of solid-state materials, Keplerate polyoxometalate compounds, and the development of homogeneous first-row early transition metal catalysts. The journal features research papers, communications, and perspectives on cutting-edge advancements in the field of inorganic chemistry. [Extracted from the article]

The oxygen reduction reaction (ORR) remains an important fixture in biological and synthetic systems for energy conversion and chemical functionalization. Late transition metals continue to dominate in the development of new catalyst systems, inspired by well-characterized metallocofactors and prior successes. By comparison, metals to the left of Fe on the periodic table are relatively understudied for the ORR. This Frontier article summarizes advancements related to the use of Mn, Cr, and V in homogeneous catalyst systems for the ORR and discusses the implications of these results for the development of catalyst systems from these metals and those earlier in the transition metal series. [ABSTRACT FROM AUTHOR]

The use of catalase (CAT) from bovine liver as an electrocatalyst in the air electrode of a primary zinc–air battery (ZAB) with neutral electrolyte (pH 7.4) is reported. First, the use of Nafion for immobilizing CAT onto electrode surface allowed to obtain long‐term stability of the catalytic activity of CAT. Besides, analysis of the CAT and CAT‐Nafion as catalysts for oxygen reduction reaction (ORR) was carried out by linear sweep voltammetry (LSV) using a rotating ring‐disk electrode (RRDE), demonstrating a four‐electron ORR mechanism. Finally, CAT and CAT‐Nafion were tested as air electrodes in flooded ZAB and compared against human hemoglobin‐based ZAB. Our results demonstrated the significant influence of the protein coating of the heme groups on the ZAB performance, affecting greatly the discharge capacity and the power density. [ABSTRACT FROM AUTHOR]

The synthesis of cone‐shaped Pt nanoparticles featuring compressively‐strained {111} facets by depositing Pt atoms on the vertices of Pd icosahedral nanocrystals, followed by selective removal of the Pd template via wet etching, is reported. By controlling the lateral dimensions down to ca. 3 nm, together with a thickness of ca. 2 nm, the Pt cones show greatly enhanced specific and mass activities toward oxygen reduction, with values being 2.8 and 6.4 times those of commercial Pt/C, respectively. Both the strain field and the observed activity trend are rationalized using density functional theory calculations. With the formation of ultrathin linkers among the Pt cones derived from the same Pd icosahedral seed, the interconnected Pt cones acquire stronger interactions with the carbon support, preventing them from detachment and aggregation during the catalytic reaction. Even after 20 000 cycles of accelerated durability test, the Pt cones still show a mass activity 5.3 times higher than the initial value of the Pt/C. [ABSTRACT FROM AUTHOR]

Developing low-cost, high-performance oxygen reduction reaction (ORR) catalysts is crucial for the commercialization of fuel cells and zinc-air batteries. Herein, we report a lignin-derived Fe/N co-doped 3D porous carbon electrocatalyst Fe-NLC-1 as an alternative to commercial Pt/C catalysts, which was synthesized by a green and facile in situ carbonization strategy. Fe-NLC-1 exhibits higher oxygen reduction activity with a half-wave potential (E 1/2) of 0.90 V vs. RHE than commercial 20 wt% Pt/C (E 1/2 = 0.85 V) in the alkaline conditions, as well as excellent methanol tolerance and stability. Furthermore, the Zn-air battery loaded with Fe-NLC-1 exhibits a maximum power density of 125 mW cm−2, an open circuit voltage of 1.477 V, and stable discharge performance, which are comparable or even better than the commercial Pt/C. This study highlights the potential of biomass-derived porous carbon materials for the development of high-performance ORR electrocatalysts. [Display omitted] • Industrial waste lignosulfonate is used to prepare an oxygen reduction catalyst. • The precursor of the porous carbon material is prepared using an in-situ template method. • Fe-NLC-1 with a 3D porous structure has a high specific surface area and excellent ORR performance. [ABSTRACT FROM AUTHOR]

Catalytic technologies are pivotal in enhancing energy efficiency, promoting clean energy production, and reducing energy consumption in the chemical industry. The pursuit of novel catalysts for renewable energy is a long-term goal for researchers. In this work, we synthesized three two-dimensional covalent organic frameworks (COFs) featuring electron-rich carbazole-based architectures and evaluated their catalytic performance in photocatalytic organic reactions and electrocatalytic oxygen reduction reactions (ORRs). Pyrene-functionalized COF, termed as FCTD-TAPy, demonstrated excellent photocatalytic performance for amino oxidation coupling and showed a remarkable preference for substrates with electron-withdrawing groups (up to >99% Conv. and >99% Sel). Furthermore, FCTD-TAPy favored a four-electron transfer pathway during the ORR and exhibited favorable reaction kinetics (51.07 mV/dec) and a high turnover frequency (0.011 s−1). In contrast, the ORR of benzothiadiazole-based FCTD-TABT favored a two-electron transfer pathway, which exhibited a maximum double-layer capacitance of 14.26 mF cm−2, a Tafel slope of 53.01 mV/dec, and a hydrogen peroxide generation rate of 70.3 mmol g−1 h−1. This work underscores the potential of carbazole-based COFs as advanced catalytic materials and offers new insights into the design of metal-free COFs for enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Non‐precious metal‐based nitrogen‐doped carbon (M‐Nx/C) shows great potential as a substitute for precious metal Pt‐based catalysts. However, the conventional pyrolytic methods for forming M‐Nx/C active sites are prone to issues such as the lack of synergistic interactions among bimetallic atoms and the potential encasement of active sites, leading to compromised catalytic efficiency and hindered mass transfer. In this work, a highly active FeCo‐N‐C@U‐AC electrocatalyst is developed with a high density of active sites, adequate exposure of catalytic sites, and robust mass transfer capability using the chemical vapor‐phase deposition (CVD) technique. The resulting catalyst demonstrates impressive oxygen reduction reaction (ORR) catalytic performance and stability, with half‐wave potentials of 0.820 V (0.1 M HClO4) and 0.911 V (0.1 M KOH), respectively. It also exhibits significantly enhanced stability, retaining 93.25% and 98.38% of current after continuous 50 000 s of durability testing, surpassing the retention rates of Pt/C (80.31% in HClO4 and 84.96% in KOH electrolytes). Notably, when employed as a cathode catalyst in proton exchange membrane fuel cells (PEMFCs) and zinc‐air flow batteries (ZAFBs), the FeCo‐N‐C@U‐AC catalyst delivers peak power densities of 859 and 162 mW·cm−2, respectively, showcasing competitive performance comparable to benchmark Pt/C. [ABSTRACT FROM AUTHOR]

This article critically examines the reduction mechanisms and energy transfer processes between trivalent europium ions (Eu3+) and divalent europium ions (Eu2+) in materials synthesized in an air atmosphere. It also encompasses various materials and conditions, including a critical analysis of the reduction mechanism and energy transfer between Eu3+ and Eu2+ in Eu-doped materials. Specific investigations include exploring the reduction process in BaMgSiO4:Eu, focusing on factors influencing the reaction. The article also covers low-temperature self-reduction, addressing conditions and mechanisms such as the charge compensation model and laser-induced reduction. Additionally, it explores the influence of charge compensation on luminescent properties, emphasizing enhancements in red emission. Investigations into the role of oxygen vacancies in the reduction of Eu3+ and their implications on material properties are presented. This article further digs into abnormal reduction processes and the formation of defect centers in Eu3+-doped pollucite, proposing a substitution defect model for the self-reduction of europium ions in silicate Ba(Eu)MgSiO4 phosphors. Unusual reduction phenomena, such as reduction via boiling water in Yb2Si2O7:Eu3+ phosphors, and reductions in various glass systems, including porous glass, ZnO–B2O3–P2O5 glasses, aluminoborosilicate glasses, europium-doped Li2B4O7 glass, and aluminosilicate oxyfluoride glass (AOG), are also thoroughly examined. [ABSTRACT FROM AUTHOR]

Activation, break‐in, and/or pre‐treatment protocols are generally applied to energy conversion devices before regular operation to reach stable performance. There remains much to understand about the relationships among physical properties, performance, and electrochemical pre‐treatments. Here, a design‐of‐experiments (DoE) strategy is employed to address this gap by demonstrating the influence of five pre‐treatment parameters for carbon‐supported Pt‐nanoparticle catalysts on the electrocatalytic oxygen reduction reaction (ORR). A subset of pre‐treatments, developed using a central composite design, are tested in a flow cell combined with an inductively‐coupled plasma mass spectrometer (on‐line ICP‐MS). The DoE‐based approach facilitates comprehensive insights from two orders of magnitude fewer experiments than a conventional grid search. The coupled on‐line ICP‐MS setup enables effective catalysis and real‐time catalyst dissolution data. Leveraging insights from DoE for on‐line ICP‐MS and additional characterization, a model is built between the degradation of a multi‐dimensional supported Pt surface, its performance, and applied electrochemical parameters. These investigations identify surface modifications, such as oxidation, and subsequent restructuring of Pt during pre‐treatment as a primary cause of performance deterioration during ORR. By combining DoE with advanced characterization techniques, a powerful approach is demonstrated to gain a mechanistic understanding of pre‐treatment protocols that can be broadly adapted to various reaction chemistries. [ABSTRACT FROM AUTHOR]

Air cathode microbial fuel cell (MFC) can use the biological activities of microorganisms to convert organic matter into ideal electrical energy, but this efficiency has not been satisfactory. The air cathode requires an optimal catalyst to enhance the power output of the MFC by improving its low oxygen reduction reaction (ORR) activity. Micro Cu-doped Co3O4 nano-flower-like catalyst is successfully synthesized in this study using a metal-organic framework as the precursor material. The addition of 5% Cu induces a higher concentration of oxygen vacancies, thereby optimizing the local electronic state of the active site and enhancing the catalytic performance for oxygen reduction in the 5% Cu-Co3O4 material. Consequently, when equipped with this material, the power output of the air cathode MFC is approximately 2.85 times greater than that achieved with pure Co3O4. This provides a novel design idea for the application of nano-flower-like transition metal oxygen reduction catalysts in MFC. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) has a crucial impact on the energy conversion efficiency and the performance of fuel cells, it is urgent to deliver low‐cost efficient ORR catalysts for the aim to scale up the utilization of fuel cells. In this study, three oxamidate copper(II) complexes [Cu2(trans‐L)(H2O)2(ClO4)2]·2H2O (Cuox), [Cu2(cis‐L)(bpy)(ClO4)2]·CH3OH (Cuoxbpy), and [Cu2(cis‐L)(mebpy)(ClO4)](ClO4) (Cuoxmebpy) (L = N,N–bis(2–pyridylmethyl)oxamide, bpy = 2,2′–bipyridine, and mebpy = 4,4′–dimethyl–2,2′–bipyridine) were prepared and characterized. The configuration of L varied from the trans form to the cis form as the bipyridines were introduced to the dicopper complex. The redox properties of three oxamidate copper(II) complexes and their catalytic activities for the ORR were studied in neutral aqueous solutions. The ORR onset potentials by Cuox, Cuoxbpy, and Cuoxmebpy were 0.417, 0.502, and 0.481 versus RHE, respectively. Three complexes homogeneously catalyzed the ORR to predominantly generate H2O2. A bimolecular catalytic pathway was proposed for the ORR mediated by Cuox, whereas a single‐molecular pathway was by Cuoxbpy and Cuoxmebpy. This work demonstrated that oxamidate metal complexes are promising ORR catalyst candidates provided that their electronic structures are appropriately tuned by altering the substituent on the organic ligands. [ABSTRACT FROM AUTHOR]

Hospital patients with infectious respiratory diseases frequently require oxygen which may be delivered by a face mask, and the quantitative effect of such masks on the emission of infectious respiratory aerosol is relevant to hospital acquired respiratory infections. This article reports the evaluation of the efficiency of aerosol particle volume reduction by oxygen face masks with and without exhalation filtering capability, for a medium concentration, high concentration non-rebreather and a venturi mask. The masks include two prototype filtering oxygen masks, and also type IIR surgical and FFP2 masks for reference. The evaluation was with a breathing and coughing manikin, measuring the relative volume of aerosol particles transmitted to the environment with and without a mask in place. Mask efficiency fraction indices, MEF, and relative performance factors, RPF, were calculated by a model which included the particle size spectrum arising from human breathing, speaking and coughing to produce indices for each of these activities. In this manikin model non-filtering medium and high concentration oxygen face masks reduced aerosol emission, with fractional efficiencies between 0.12 on breath and 0.65 on cough. Compared to non-filtering masks, currently available filtering oxygen masks reduced aerosol particle volume emission by factors up to 1.2 on breath and 2.4 on cough, and with prototype filtering masks reduction was up to a factor of 6.1 for breathing and 5.1 for cough. Validation in humans and modeling of the clinical environment is required to estimate the effect of such reductions in aerosol emission on healthcare acquired infections. [ABSTRACT FROM AUTHOR]

[Display omitted] The electrocatalytic oxygen reduction reaction (ORR) is crucial for energy conversion systems such as fuel cells and metal-air batteries. Boron carbon nitrogen (BCN) is a novel functional material with a high specific surface area, excellent corrosion resistance, and outstanding electrochemical stability. These properties make BCN an effective ORR catalyst and a promising support for metal catalysts. This study leveraged the strong interaction between BCN and metals to anchor platinum nanoparticles (Pt NPs) onto the BCN surface (Pt/BCN), significantly enhancing the durability of traditional Pt/C catalysts in ORR. The half-wave potential of Pt/BCN is 0.927 V, higher than Pt/XC-72R (0.857 V) and commercial Pt/C (0.879 V). Notably, after 10,000 durability test cycles, the mass activity (MA) of Pt/XC-72R and commercial Pt/C decreased by 67 % and 75 %, respectively. Even after 50,000 cycles, Pt/BCN exhibited only a 54 % decrease in MA. Experimental data and density functional theory calculations confirmed increased electron transfer from Pt to the BCN support, indicating a strong electronic metal-support interaction (EMSI) between Pt and BCN. This strong EMSI effectively anchored the Pt NPs, preventing migration and aggregation during the ORR process. Consequently, our research introduces a novel electrocatalyst support material with significant potential for ORR and broader applications. [ABSTRACT FROM AUTHOR]

The difference of work functions induces the build-in electric field in NiS/MoS 2 heterointerface, leading to electron density increase of interfacial Ni atoms, which enhances the adsorption of LiO 2 with one-electron oxygen reduction/oxidation processes. [Display omitted] Electrocatalysts with appropriate electron coupling toward LiO 2 intermediates can exhibit superior oxygen reduction/evolution reaction kinetics in Li-O 2 batteries (LOBs). In this work, a charge redistribution strategy has been developed by constructing NiS/MoS 2 heterostructure nanosheet self-assembled hollow microspheres with an internal electric field to regulate the interaction with LiO 2 and then improve the electrochemical performance of LOBs. Density functional theory calculations and physicochemical characterizations reveal that the difference of work functions between NiS and MoS 2 promotes the electron redistribution in heterointerface via built-in electrical field, leading to increased electron density of interfacial Ni atom, thereby enhancing its electron coupling toward LiO 2 intermediates and promoting one-electron oxygen reduction/oxidation reaction kinetics. As a result, the NiS/MoS 2 -based LOBs exhibit evidently higher discharge capacity and much better cycling performance than the batteries using NiS and MoS 2. This work provides a reliable charge redistribution strategy induced by build-in electric field to design efficient catalysts for LOBs. [ABSTRACT FROM AUTHOR]

Novel Fe N C electrocatalysts derived from conjugated microporous polymers based on pre-functionalization of monomers was developed, which exhibits great potential for cathodic oxygen reduction reaction in fuel cell and provides a feasible strategy of developing multi-atoms doping catalysts for heterogeneous catalysis. [Display omitted] Porous iron–nitrogen-doped carbons (Fe N C) offer a great platform for construction of cathodic oxygen reduction reaction (ORR) catalysts in fuel cells. However, challenges still remain regarding with the collapse of carbon-skeleton during pyrolysis, uneven distribution of active sites and aggregation of metal atoms. In this work, we synthesized Fe, N co-doped conjugated microporous polymer (FeN-CMP) through a facile bottom-up strategy using 1,3,5-triethynylbenzene and iron-chelated 3,8-dibromo-1,10-phenanthroline as monomers, ensuring the uniform coordination of N with Fe element in network. Then, the resulting FeN-CMP was treated by pyrolysis without structural collapse to obtain porous Fe N C electrocatalyst for ORR. The most active catalyst was fabricated under 900 °C, which exhibits remarkable ORR activity in alkaline medium with half-wave potential of 0.796 V (18 mV and 105 mV positive deviation from the commercial Pt/C catalyst and post-doping catalyst), high selectivity with nearly 4e- transfer process and excellent methanol tolerance. Our study first developed porous Fe N C electrocatalysts derived from Fe, N -anchoring CMPs based on pre-functionalization of monomers, which exhibits great potential as an alternative to commercial Pt/C catalyst for ORR, and provides a feasible strategy of developing multi-atoms doping catalysts for energy storage and conversion as well as heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogen peroxide (H 2 O 2) emerges as a viable oxidant for fuel cells, necessitating the development of an efficient and cost-effective electrocatalyst for the hydrogen peroxide reduction reaction (HPRR). In this study, we synthesized a self-supporting, highly active HPRR electrocatalyst comprising two morphologically distinct components: CeO 2 -NiCo 2 O 4 nanowires and CeO 2 -NiCo 2 O 4 metal organic framework derivatives, via a two-step hydrothermal process followed by air calcination. X-ray diffraction and transmission electron microscopy analysis confirmed the presence of CeO 2 and NiCo 2 O 4 , revealing the amalgamated interface between them. CeO 2 exhibits multifunctionality in regulating the surface electronic configuration of NiCo 2 O 4 , fostering synergistic connections, and introducing oxygen deficiencies to enhance the catalytic efficacy in HPRR. Electrochemical measurements demonstrate a reduction current density of 789.9 mA·cm−2 at −0.8 V vs. Ag/AgCl. The assembly of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) exhibits a peak power density of 45.2 mW·cm−2, demonstrating durable stability over a continuous operation period of 120 h. This investigation providing evidence that the fabrication of heterostructured catalysts based on CeO 2 for HPRR is a viable approach for the development of high-efficiency electrocatalysts in fuel cell technology. [ABSTRACT FROM AUTHOR]

CoNOC with CoN (Pd)3 N (Po)1 O1 structure can efficiently catalyse the electro-Fenton reaction to generate –OH to degrade antibiotic pollutants represented by tetracyclines. [Display omitted] • Oxygen-doped Co SACs were prepared using a temperature gradient pyrolysis strategy with nitric acid oxidation method. • DFT calculations explained the excellent catalytic performance was due to the electronic modulation of Co sites by the O doping and N coordination. • TC degradation of 95 % in 120 min and mineralization efficiency of almost 90 % in 180 min were achieved in the electro-Fenton system. • The significant involvement of OH was confirmed, and the degradation pathways of TC have been analyzed and predicted. Electro-Fenton is an effective process for degrading hard-to-degrade organic pollutants, such as tetracycline (TC). However, the degradation efficiency of this process is limited by the activity and stability of the cathode catalyst. Herein, a temperature gradient pyrolysis strategy and oxidation treatment is proposed to modulate the coordination environment to prepare oxygen-doped cobalt monoatomic electrocatalysts (CoNOC). The CoNOC catalysts can achieve the selectivity of 93 % for H 2 O 2 with an electron transfer number close to 2. In the H-cell, the prepared electrocatalysts can achieve more than 100 h of H 2 O 2 production with good stability and the yield of 1.41 mol g catalyst −1 h−1 with an average Faraday efficiency (FE) of more than 88 %. The calculations indicate that the epoxy groups play a crucial role in modulating the oxygen reduction pathway. The O doping and unique N coordination of Co single-atom active sites (CoN (Pd)3 N (Po)1 O1) can effectively weaken the O 2 /OOH* interaction, thereby promoting the production of H 2 O 2. Finally, the electro-Fenton system could achieve a TC degradation rate of 94.9 % for 120 min with a mineralization efficiency of 87.8 % for 180 min, which provides a reliable option for antibiotic treatment. The significant involvement of OH in the electro-Fenton process was confirmed, and the plausible mineralization pathway for TC was proposed. [ABSTRACT FROM AUTHOR]