Abstract Lithium−carbon dioxide (Li−CO2) batteries are promising energy storage systems due to their high theoretical energy density and capability for CO2 utilization, yet their practical performance is limited by sluggish reaction kinetics. Here, we report an effective edge-site engineering strategy to enhance the catalytic activity of MoS2 nanosheets via controlled H2O2 etching. Density functional theory (DFT) calculations reveal that edge sites exhibit significantly stronger adsorption toward key intermediates (Li, CO2, and Li2CO3) than the basal plane, identifying them as dominant active centers. Guided by this insight, a series of MoS2 nanosheets with tunable edge-site densities were synthesized on carbon paper. Structural characterizations confirm that moderate etching effectively increases edge-site exposure while preserving structural integrity. Electrochemical measurements demonstrate that the optimized MoS2-45 s electrode delivers a low overpotential of 0.77 V, excellent rate capability, and stable cycling over 700 h with an energy efficiency exceeding 75%. In short, our work highlights the critical role of edge-site regulation in improving catalytic performance and provides a rational strategy for designing advanced cathode materials for Li−CO2 batteries.

We report a systematic study of superconductivity on Fe1-xZnxSe single crystals synthesized over a broad Zn doping range (x = 0-0.023). High-quality single crystals across all compositions range exhibit superconducting transitions, while the transition temperature Tc shows a pronounced nonmonotonic dependence on Zn doping concentration, indicating that the underlying mechanism govering Tc its evolution cannot be explained solely by simple impurity pair breaking alone. Magnetization and transport measurements confirm the bulk behavior of superconductivity and reveal enhanced scattering effects with Zn doping. Low-temperature specific heat is consistently described by a two-gap scenario composed of an isotropic s-wave gap and an anisotropic extended s-wave gap, whereas single-gap and alternative pairing symmetries fail to describe the data. The nearly unchanged relative weights of the two gap components suggest the weak interband scattering induced by Zn substitution, thereby preserving multiband superconductivity. These results demonstrate the robustness of multigap superconductivity in FeSe and impose stringent constraints on candidate pairing mechanisms, highlighting the role of multiband electronic structure and anisotropic gap formation.

In this work, the electrocatalytic activity of hexagonal perovskite oxide 10H-BaCo0.9Ru0.1O3-s is improved by partially substituting the Co ions with Ti, Fe, and Nb ions, synthesizing BaCo0.6Ti0.3Ru0.1O3-s, BaCo0.6Fe0.3Ru0.1O3-s, and BaCo0.6Nb0.3Ru0.1O3-s, respectively. These three substituted samples preserve the original 10Htype hexagonal perovskite structure. Among them, BaCo0.6Fe0.3Ru0.1O3-s exhibits the lowest overpotential of 306 mV at 10 mA cm-geo,2 which is better than the pristine 10H-BaCo0.9Ru0.1O3-s (391 mV), BaCo0.6Ti0.3Ru0.1O3-s (418 mV), BaCo0.6Nb0.3Ru0.1O3-s (404 mV), and benchmark material RuO2 (348 mV), mainly due to the Fe substitution increases in surface Co average oxidative state and enhances the proportion of surface OH-/O2 species. Notably, Fe substitution induces a shift in the oxygen evolution reaction (OER) pathway from the adsorption evolution mechanism to the lattice oxygen participation mechanism, and BaCo0.6Fe0.3Ru0.1O3-s retains a stable surface structure without reconstruction under prolonged OER operation. Additionally, these three samples show paramagnetic characteristics at room temperature. Further inferred that the surface Co3+ ions in Ti and Nb substituted samples maintain the high spin state consistent with the pristine 10H-BaCo0.9Ru0.1O3-s, but adopt a low spin state in the BaCo0.6Fe0.3Ru0.1O3-s. Our work demonstrates that the B-site substitution strategy effectively tunes the electronic environment of 10H-BaCo0.9Ru0.1O3-s, providing valuable insights for the rational design of high-performance hexagonal perovskite electrocatalysts.

The standard solid oxide fuel cells (SOFCs) interconnects are ferritic stainless steels such as SUS430. However, these steels present serious issues such as chromium poisoning and oxidation of ferritic stainless steel interconnects. Here, we report a CuFe2O4/CuO bilayer protective coating deposited on SUS430 interconnects via ultrasonic spray deposition, a scalable and conformal surface engineering technique. The bilayer architecture combines a conductive CuFe2O4 spinel inner layer and a CuO outer diffusion barrier to synergistically suppress chromium migration and oxidation reaction while maintaining low electrical resistance. The coating exhibits uniform coverage, strong adhesion, and excellent structural stability after extended exposure at 800 degrees C. Compared to bare and single-layer CuFe2O4-coated steels, the bilayer coating significantly inhibits Cr2O3 scale formation, limiting its thickness to similar to 3 mu m after 1000 h. Long-term oxidation tests over 1000 h show a marked reduction in the parabolic oxidation rate constant, corresponding to a protection factor of 86.6%. Notably, the bilayer coating achieves low area-specific resistance, with values of 2.4 m Omega cm(2) after 100 h and below 7.6 m Omega cm(2) after 1000 h at 800 degrees C. Electrochemical impedance spectroscopy on symmetrical cells confirms that the bilayer coated interconnect effectively mitigates chromium-induced degradation of the oxygen reduction reaction, preserving cathode activity and interfacial stability. This work establishes the CuFe2O4/CuO bilayer, as a robust and scalable engineered solution for durable, high-performance SOFC interconnects.

Ir substitution in Ir0.1 boosts bifunctional electrocatalysis by raising the O 2 2− /O − ratio, upshifting the d-band center, and increasing high-spin Co 3+ content, synergistically enhancing its activity.

Carbon dioxide electroreduction (CO2R) in acid tends to be a promising route to avoid CO2 loss in alkaline and neutral electrolytes; however, high alkali cation concentrations (typically ≥3 M) are required to activate CO2 and suppress water electroreduction, causing carbonate formation and thus unsatisfied single-pass carbon efficiency (SPCE). Based on theoretical and experimental analyses, we show that an inherent trade-off exists: increasing cation concentrations improves Faradaic efficiency (FE) toward CO2R products but comes at the expense of reduced SPCE. We demonstrate a polyimide-modification strategy to overcome this trade-off by taking advantage of the amino groups that can effectively capture protons, creating a local alkaline microenvironment surrounding the electrode surface. In a proof-of-concept experiment, SnO2 nanoparticles were modified with polyimide and acted as a CO2R catalyst, which achieved, simultaneously, near-ideal SPCE of 95.7% and FE of 96% (toward HCOOH) at pH 1.36 with dilute potassium ions down to even 0.1 M. We expect that these findings will accelerate the development of carbon- and electron-efficient acidic CO2 electrolysis.

Perovskite oxide La0.5Sr0.5FeO3-delta (LSF) is a potential Co-free electrocatalyst for oxygen reduction reaction (ORR) in solid oxide fuel cells (SOFCs). To improve its catalytic activity, this work performs multi-element doping to the A-site elements La and Sr, forming a high-entropy oxide Ba0.2Sr0.2La0.2Pr0.2Sm0.2FeO3-delta (H-LSF) and a medium- entropy material Ba0.35Sr0.35La0.1Pr0.1Sm0.1FeO3-delta (M-LSF). The multi-element doping effects are investigated on various physicochemical properties including crystalline structure, chemical compatibility with electrolyte, valence state of B-site Fe, amount of adsorbed oxygen species, oxygen nonstoichiometric value, sinterability, thermal expansion coefficient, electrical conductivity, chemical oxygen surface exchange coefficient (kchem), and electrochemical performance. While the multi-element doping does not change the phase structure and compatibility, it decreases the electronic conductivity, increases the oxygen vacancy concentration and kchem. Consequently, it improves ORR activity such as reduces interfacial polarization resistance and elevates peak power density. The best performance is observed with the medium-entropy perovskite rather than the high- entropy material. M-LSF shows kchem of 21.5 x 105 cm s- 1 at 750 degrees C, 32 % higher than H-LSF and 4 times as high as LSF. In addition, M-LSF electrode exhibits interfacial polarization resistance of 0.090 2 at 750 degrees C, about 1/2 of H-LSF and 1/5 of LSF. Furthermore, single cell with M-LSF cathode demonstrates peak power density of 1.72 W cm- 2 at 800 degrees C, 25 % higher than H-LSF and more than twice as LSF. Therefore, multi-element doping to the A-site of ferrite-based cobalt-free perovskite could be an effective method to improve the cathode performance.

We report a systematic study of the magnetic, electrical, specific heat, and electrocatalytic properties of the quasi-one-dimensional hexagonal perovskite oxide Sr6(Co0.955Fe0.045)5O15 high-quality single crystal. Magnetic susceptibility exhibits an antiferromagnetic ground state perpendicular to the spin-chain direction (the c axis) and a ferromagnetic state along the c axis. Notably, the broad peak near 90 K possibly originates from short-range spin correlations rather than a typical spin-glass or cluster-glass state, and the estimated frustration factor indicates the presence of spin frustration, reflecting competing magnetic interactions. The specific heat data show that the average sound velocity in Fe-substituted Sr6Co5O15 is lower than that of parent Sr6Co5O15, attributing to the significant scattering of conduction phonons by magnetic impurities. Intriguingly, in the Sr6(Co1-xFex)5O15 single-crystal system, the Fe content significantly influences the electrocatalytic performance for hydrogen evolution reaction (HER). Furthermore, each single crystal displays pronounced electrocatalytic anisotropy, offering insights into their intrinsic physical properties while highlighting their potential for future applications.

Defect engineering is essential for the development of efficient electrocatalysts at the atomic level. While most work has focused on various vacancies as effective catalytic modulators, little attention has been paid to the relation between the local atomic environment of vacancies and catalytic activities. To face this challenge, we report a facile synthetic approach to manipulate the local atomic environments of vacancies in MoS2 with tunable Mo-to-S ratios. Our studies indicate that the MoS2 with more Mo terminated vacancies exhibits better hydrogen evolution reaction (HER) performance than MoS2 with S terminated vacancies and defect-free MoS2. The improved performance originates from the adjustable orbital orientation and distribution, which is beneficial for regulating H adsorption and eventually boosting the intrinsic per-site activity. This work uncovers the underlying essence of the local atomic environment of vacancies on catalysis and provides a significant extension of defect engineering for the rational design of transition metal dichalcogenides (TMDs) catalysts and beyond.

To systematically investigate the influence of the number of [AO3] layers in the unit cell of hexagonal perovskite oxide on the oxygen evolution reaction performance, we successfully synthesized the three new hexagonal perovskite oxides 2H-BaCo0.9Ru0.1O3-delta, 6H-BaCo0.9Ru0.1O3-delta, and 10H-BaCo0.9Ru0.1O3-delta with the same element composition but different [BaO3] layers via the sol-gel method. Here, 2H, 6H, and 10H refer to the number of [BaO3] layers contained in the unit cell of the BaCo0.9Ru0.1O3-delta system. Experimentally, 10H-BaCo0.9Ru0.1O3-delta, featuring ten layers of [BaO3], exhibits optimal electrochemical activity among the three oxide catalysts, and in situ Raman results under various bias voltages confirm its ability to maintain a high surface crystal structural stability. Notably, as the number of [BaO3] layers increases, the effective magnetic moments and the valence state of surface Co ions in these three catalysts also increase, with the spin configuration of the surface Co ions being in a high-spin state. More importantly, DFT calculations provide the evolution rules of the p-band center (epsilon p) with the number of [BaO3] layers, predicting the electrochemical performance of the BaCo0.9Ru0.1O3-delta system with different [BaO3] layers. Our experimental results offer a distinctive perspective for the future design, synthesis, and application of hexagonal perovskite oxides in electrocatalysis.

Solid oxide electrolysis cells (SOECs) are regarded as a promising technology to realize carbon neutrality since they can electrochemically convert CO2 to CO. This communication reports a feasible structure of a metal-supported solid oxide electrolysis cell (Ms-SOEC) for CO2 electrolysis, where a porous 430 stainless steel substrate is coated with perovskite oxide La0.6Sr0.4Fe0.9Mo0.1O3-d (LSFM) introduced by the infiltration method. The LSFM catalyst exhibits a uniform distribution and loose accumulation in the porous metal substrate. This Ms-SOEC with a structure of LSFM-430|YSZ|LSCF-SDC shows a current density of 0.90 A cm-2 at 800 degrees C and 1.5 V with an LSFM loading of 6.0 wt%. Meanwhile, a 10-times thermal cycling operation demonstrates good reliability of the configuration. Overall, the metal-based cathode, where 430 stainless steel acts as the mechanical support and infiltrated LSFM perovskite acts as the electrocatalyst for CO2 electrolysis, could be a viable configuration of Ms-SOECs.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

We present a study on the electrocatalysis of 214-type perovskite oxides LnSrCoO4 (Ln = La, Pr, Sm, Eu, and Ga) with semiconducting-like behavior synthesized using the sol-gel method. Among these five catalysts, PrSrCoO4 exhibits the optimal electrochemical performance in both the oxygen evolution reaction and the hydrogen evolution reaction, mainly due to its larger electrical conductivity, mass activity, and turnover frequency. Importantly, the weak dependency of LSV curves in a KOH solution with different pH values, revealing the adsorbate evolving mechanism in PrSrCoO4, and the density functional theory (DFT) calculations indicate that PrSrCoO4 has a smaller Gibbs free energy and a higher density of states near the Fermi level, which accelerates the electrochemical water splitting. The mutual substitution of different rare-earth elements will change the unit-cell parameters, regulate the electronic states of catalytic active site Co ions, and further affect their catalytic performance. Furthermore, the magnetic results indicate strong spin-orbit coupling in the electroactive sites of Co ions in SmSrCoO4 and EuSrCoO4, whereas the magnetic moments of Co ions in the other three catalysts mainly arise from the spin itself. Our experimental results expand the electrochemical applications of 214-type perovskite oxides and provide a good platform for a deeper understanding of their catalytic mechanisms.

Magnetism, transport and specific heat measurements have been performed to the hexagonal perovskite 20% Fe-substituted Sr6Co5O15 (that is Sr6(Co0.8Fe0.2)5O15) polycrystalline samples with quasi-one-dimensional structure. The system exhibits paramagnetism above 270 K, and with decreasing temperature, it undergoes two ferromagnetic phase transitions FM-I and FM-II at 220 K and 170 K, respectively, which correspondingly show two downward jumps on the resistivity curve of 0 T. The 20% Fe-substituting-induced changes in magnetic properties are discussed to be due to the changes in spin exchanges.

Nitrophenols are important nitroaromatic compounds, both important environmental pollutants and dangerous explosives, posing a devastating danger and pollution threat to humans. It is vital to detect efficiently trace nitrophenols in the environment. In this contribution, a series of fully flexible cyclotriphosphazene-based COFs (FFCP COFs: HDADE, HBAPB, and HBPDA), prepared with both a flexible knot and flexible linkers of different lengths, were used for sensing 2,4,6-trinitrophenol (TNP) and p-nitrophenol (p-NP) in real time with excellent sensitivity and selectivity. The quenching constants of HDADE by TNP, HBAPB, and HBPDA by p-NP are 6.29 × 104, 2.17 × 105, and 2.48 × 105 L·mol–1, respectively. The LODs of TNP and p-NP are 1.19 × 10−11, 6.91 × 10−12, and 6.05 × 10−12 mol·L−1. Their sensitivities increase with the linker length, which is better than the corresponding COFs composed of rigid linkers. There is only a photoinduced electron transfer mechanism in the fluorescence quenching of HBPDA by p-NP. Meanwhile, the mechanisms of photoinduced charge transfer and resonance energy transfer exist in the fluorescence quenching of HDADE by TNP and the fluorescence quenching of HBAPB by p-NP.

Intercalation chemistry describes the process by which a guest is intercalated into a host to form an inter? calated compound. Intercalation chemistry, as an effective method to modify structures, has been intensively studied in recent centuries for electrocatalysis-based energy storage and conversion devices. Particularly, research on transi? tion metal oxides(TMOs) has become an emerging frontier in intercalation chemistry because of their tunability in structure and composition. Nonetheless, confusions remain in the discovery of indefinable intercalation mechanism and unexplained properties change. In this paper, a first-ever in-depth description of the intercalation mechanism, which directly determines the potential of properties and applications, will be presented. We discuss the major synthesis strategies for TMOs intercalation compounds. We summarize the recent advances for electrocatalytic appli? cations of intercalated TMOs. Moreover, this review will be concluded with a section on the future opportunities and challenges for intercalation of TMOs.

Double perovskite oxide PrBaFe2O5+δ is a potential cathode material for intermediate-temperature solid oxide fuel cells. To improve its electrochemical performance, the trivalent element Ga is investigated to partially replace Fe, forming PrBaFe2-xGaxO5+δ (PBFGx, x = 0.05, 0.1, and 0.15). The doping effects on physicochemical properties and electrochemical properties are analyzed regarding the phase structures, element valence states, amount of oxygen vacancies, content of oxygen species, oxygen surface exchange coefficients (kchem), electrochemical polarization resistance, and single-cell performance. Specifically, PBFG0.1 exhibits improved kchem, such as a 19% improvement from 4.09 × 10-4 to 4.86 × 10-4 cm s-1 at 750 °C, due to the increased concentration of reactive oxygen species and oxygen vacancies. Consequently, the interfacial polarization resistance is decreased by 28% from 0.057 to 0.041 Ω cm2 at 800 °C. The subreaction steps of the oxygen reduction reaction in the PBFG0.1 cathode are further investigated, which suggests that the oxygen dissociation process is greatly enhanced by doping Ga. Meanwhile, doping Ga increases the peak power density of the anode-supported single cell by 36% from 629 to 856 mW cm-2 at 800 °C. The single cell with the PBFG0.1 cathode also exhibits good stability in 100 h of long-term operation at 750 °C.

Electrochemical synthesis of valuable chemicals and feedstocks through carbon dioxide (CO2) reduction in acidic electrolytes can surmount the considerable CO2 loss in alkaline and neutral conditions. However, achieving high productivity, while operating steadily in acidic electrolytes, remains a big challenge owing to the severe competing hydro-gen evolution reaction. Here, we show that vertically grown bismuth nanosheets on a gas- diffusion layer can create numerous cavities as electrolyte reservoirs, which confine in situ-generated hydroxide and potassium ions and limit inward proton diffusion, producing locally alkaline environments. Based on this design, we achieve formic acid Faradaic efficiency of 96.3% and partial current density of 471 mA cm-2 at pH 2. When operated in a slim continuous -flow electrolyzer, the system exhibits a full -cell formic acid energy efficiency of 40% and a single pass carbon efficiency of 79% and performs steadily over 50 h. We further demonstrate the production of pure formic acid aqueous solution with a concentration of 4.2 weight %.

We report a study on the catalytic performance of severaltypicalcubic perovskite oxides Pr0.5Sr0.5Co0.8Fe0.2O3-delta, Ba0.5Sr0.5Co0.8Fe0.2O3-delta, and SrCo0.8Fe0.2O3-delta prepared by using the sol-gel method. Pr0.5Sr0.5Co0.8Fe0.2O3-delta calcined at 700 degrees C exhibits the lowest overpotential of 320mV in 1 M KOH at 10 mA cm(-2) and the highest massactivity of 23.84 A g(-1) at 1.55 V vs. RHE, attributing to its larger surface area, better charge-transferability, and the optimal e(g) orbital electron filling. Furthermore,we also found that these several catalysts display paramagnetic- andsemiconducting-like behaviors at room temperature. In short, our researchexpands the application of perovskite oxides in electrocatalytic oxygenevolution.

The high overpotential required for the oxygen evolution reaction (OER)-due to the transfer of four protons and four electrons-has greatly hindered the commercial viability of water electrolysis. People have been committed to the development of alternative precious metal-free OER electrocatalysts, especially electrocatalysts for alkaline media. In this study, we report the application of Sr6(Co0.8Fe0.2)5O15 (SCF-H) perovskite oxide with a hexagonal phase structure in the field of OER electrocatalysis. Synthesized by a simple and universal sol-gel method, the SCF-H perovskite oxide shows prominent OER activity with an overpotential of 318 mV at a current density of 10 mA cm-2 and a Tafel slope of only 54 mV dec-1, which is significantly better than the cubic phase structure SrCo0.8Fe0.2O3-δ (SCF-C), benchmark noble-metal oxide RuO2 and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF). Compared with cubic SCF-C, the hexagonal SCF-H perovskite oxide has abundant surface oxygen species (O22-/O-), a faster charge transfer rate, and a higher electrochemical surface area. In addition, the DFT calculation results show that the center of the O p-band of SCF-H is closer to the Fermi level than that of SCF-C, which leads to the better OER activity of SCF-H. This work finds that the new hexagonal structure perovskite may become a promising OER electrocatalyst.