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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]

In order to accelerate the widespread application of solid oxide fuel cells (SOFCs), especially proton-conducing solid oxide fuel cells (PCFCs), it is crucial to develop a cathode material with high activity for the oxygen reduction reaction (ORR), excellent long-term stability and CO 2 tolerance. Herein, an A-site deficient cobalt-free (Co-free) perovskite oxide Sr 0.95 Ta 0.1 Fe 0.9 O 3-δ (S 0.95 TF) is prepared by introducing cation deficiencies into SrTa 0.1 Fe 0.9 O 3-δ (STF), and it proves to be a highly active cathode. The increased oxygen vacancies, the decreased thermal expansion coefficient (TEC) value and improved CO 2 tolerance, efficiently enhance electrochemical performance and durability during long-term stability testing. As a result, the area specific resistance (ASR) values of S 0.95 TF at 600 °C are only 0.095 and 0.42 Ω cm2 with the Sm 0.2 Ce 0.8 O 1.9 (SDC) and BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) electrolytes, respectively. In addition, both of the single cells with S 0.95 TF cathodes, based on different electrolytes, can function stably for 200 h without obvious performance decrease. These results clearly demonstrate that S 0.95 TF is a highly promising candidate for both oxygen ion-conducting SOFCs and PCFCs. [ABSTRACT FROM AUTHOR]

Lanthanum Strontium Cobalt Ferrite Oxide (LaSrCoFeO 3) has been widely used as cathode material for intermediate-temperature solid oxide fuel cells at the temperature of 500–800 °C. At this temperature range, understanding the electrochemical behavior which is commonly analyzed by complex nonlinear least-squares (CNLS) analysis is very crucial in improving the cathode's performance. However, this analysis shows some limitations in interpreting the electrochemical processes in detail, particularly at the electrode-electrolyte interface. Hence, this study is conducted to compare the electrochemical impedance data analyses by CNLS and the distribution of relaxation times (DRT) of a fabricated LaSrCoFe|BCZY|LaSrCoFe (LaSrCoFe La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 and BCZY=BaCe 0.54 Zr 0.36 Y 0.1 O 2.95) symmetrical cell. Impedance data of the cell is collected at T = 800 °C at two different stabilization times and to further enhance the analysis process, the impedance data of the cell at measurement temperatures of 700 °C and 750 °C are also included. In a Nyquist plot, the cell exhibits depressed semi-circles that represent a few processes occurring at the interface. The DRT analysis is more precise and easily reveals the semi-circles consisting of four different sub-processes (represented by four peaks) than CNLS (represented by four impedance arcs). The extracted responses from both analyses correspond to the oxygen reduction reactions that follow the Adler-Lane-Steele model. The stabilized symmetrical cells for respective 34 h and 17 h show an area-specific resistance (ASR) of (i) 0.22 Ωcm2 and 0.30 Ωcm2 (by CNLS) and (ii) 0.20 Ωcm2 and 0.26 Ωcm2 (by DRT). In addition, the ASR of the cell at T = 700 °C and T = 750 °C after being stabilized for 34 h is (iii) 0.71 Ωcm2 and 0.40 Ωcm2 (by CNLS) and (iv) 0.70 Ωcm2 and 0.44 Ωcm2 (by DRT), accordingly. Conversely, the cell's microstructure is not affected by the applied stabilization periods as observed by a scanning electron microscope. [Display omitted] • DRT analysis predominantly expresses P 1 , P 2 , P 3 and P 4 cathode sub-processes. • The 34 h stabilization period is sufficient to stabilize a 25-mm PCFC button cell. • ASR value of the S34 is lower than S17 according to DRT and CNLS analysis. • Shorter relaxation time means a faster kinetic reaction of electrochemical processes. [ABSTRACT FROM AUTHOR]

Achieving high performance and stability in cathodes for the oxygen reduction reaction is crucial for the advancement of proton ceramic fuel cells (PCFCs). The introduction of non-metal doping method presents an opportunity to simultaneously optimize the perovskite structure and augment the activity and stability of the oxygen reduction reaction. Herein, we develop a phosphorus-doped SrCo 0·8 Fe 0·15 P 0·05 O 3-δ (SCFP) cathode for PCFCs. The SCFP cathode shows a low area specific resistance of 0.24 Ω cm2 at 650 °C in wet air (5% H 2 O), which is smaller than that of the phosphorus-free SrCo 0·8 Fe 0·2 O 3-δ (SCF) electrode (0.34 Ω cm2). The Ni–BaZr 0.1 Ce 0·7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) anode-supported single cell with BZCYYb electrolyte and SCFP cathode exhibits a superior performance of 865 mW cm−2 at 650 °C under H 2 atmosphere. This underscores the effectiveness of the phosphorus-doping strategy as a promising approach for advancing cathode development in PCFCs. [Display omitted] [ABSTRACT FROM AUTHOR]

Ammonia (NH 3), a promising carbon-free energy carrier, can be directly and efficiently converted into electricity in solid oxide fuel cells (SOFCs). However, the NH 3 -fueled SOFC (NH 3 –SOFC) still suffered from several difficulties, including sluggish oxygen reduction reaction (ORR) kinetics and poor cathode durability. In this study, we develop a LSCF-GDC dual-phase cathode with uniform distribution for NH 3 –SOFC. In comparison with commercial counterpart, the dual-phase cathode shows a lower ORR resistance of 0.114 Ω cm2 for at 700 °C due to reduced grain sizes and expanded triple-phase boundary (TPB) length. The resultant NH 3 –SOFC follows the H 2 oxidation process and delivers a comparable peak power density of 0.347 Wcm−2 to H 2 –SOFC at 700 °C, which is further improved to 0.516 Wcm−2 after 280 h activation at 0.7 V. Further operation of five thermal cycles between 700 and 500 °C results in a performance degradation, which can be explained by the microstructure changes of Ni-based anode rather than the dual-phase cathode. Moreover, the thermal cycled NH 3 –SOFC can maintain stable operation without current decay at constant 700 °C and 0.7 V in the subsequent 135 h, further demonstrating the robustness of the dual-phase cathode. Therefore, the introduction of GDC into self-assembled dual-phase cathode is an effective way to synergistically promote the electrochemical activity and durability of the cathode for NH 3 –SOFC. [ABSTRACT FROM AUTHOR]

[Display omitted] The rational construction of highly active and robust non-precious metal oxygen reduction electrocatalysts is a vital factor to facilitate commercial applications of Zn-air batteries. In this study, a precise and stable heterostructure, comprised of a coupling of Co 3 Fe 7 and Fe 3 C, was constructed through an interface engineering-induced strategy. The coordination polymerization of the resin with the bimetallic components was meticulously regulated to control the interfacial characteristics of the heterostructure. The synergistic interfacial effects of the heterostructure successfully facilitated electron coupling and rapid charge transfer. Consequently, the optimized CST-FeCo displayed superb oxygen reduction catalytic activity with a positive half-wave potential of 0.855 V vs. RHE. Furthermore, the CST-FeCo air electrode of the liquid zinc-air battery revealed a large specific capacity of 805.6 mAh g Zn -1, corresponding to a remarkable peak power density of 162.7 mW cm−2, and a long charge/discharge cycle stability of 220 h, surpassing that of the commercial Pt/C catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] The sluggish kinetics and inferior stability of oxygen electrocatalyst in rechargeable zinc air battery (ZAB) hamper its industrialization. In this work, we activate cobalt telluride (CoTe) by introduction of metallic cobalt (Co) to modulate the work function to facilitate the electron transfer from Co to CoTe during oxygen catalysis; additionally, the three-dimensional porous carbon nanosheets (3DPC) are invited to reduce the resistance towards electrolyte/oxygen diffusion. Thereby, Co-CoTe@3DPC only demands 280 mV overpotential to reach 10 mA cm−2 under alkaline oxygen evolution reaction (OER) condition, relatively lower than commercial iridium oxides (IrO 2); besides, the operando electrochemical impedance spectroscopy (EIS) indicates a better resistance towards surface reconstruction than Co@3DPC leading to a superior stability. A Pt-like oxygen reduction reaction (ORR) performance, half-wave potential associated with kinetic current density, is achieved for Co-CoTe@3DPC. A maximum power density of 203 mW cm−2 is achieved and sustains for 800 h. Furthermore, the all-solid-state ZAB offers 97 mW cm−2. Theoretical calculation suggests that the incorporation of metallic Co to CoTe maintains the superb ORR activity and promotes the OER catalysis. [ABSTRACT FROM AUTHOR]

We introduce N-P pair into the carbon matrix to construct N,P-C electrocatalyst by a facile pyrolysis strategy. Benefiting from the moderate adsorption energy of *OH on the active sites (C adjacent to P atom in N-P), the achieved N,P-C-1000 displays outstanding alkaline ORR performance and high power density primary liquid and solid ZABs. [Display omitted] • N-P pair was introduced into the carbon matrix to construct N,P-C electrocatalyst by a facile pyrolysis strategy. • The catalyst exhibits superior ORR activity with a E 1/2 of 0.83 V, comparable to that of commercial 20 wt% Pt/C. • Its C-2p orbit has higher interaction strength with the intermediates, thus reducing the overall reaction energy barrier. • High power density primary liquid and solid ZABs are achieved using N,P-C-1000 as cathodic catalysts. Developing sustainable metal-free carbon-based electrocatalysts is essential for the deployment of metal-air batteries such as zinc-air batteries (ZABs), among which doping of heteroatoms has attracted tremendous interest over the past decade. However, the effect of the heteroatom covalent bonds in carbon matrix on catalysis was neglected in most studies. Here, an efficient metal-free oxygen reduction reaction (ORR) catalyst is demonstrated by the N-P bonds anchored carbon (termed N,P-C-1000). The N,P-C-1000 catalyst exhibits superior specific surface area of 1362 m2 g−1 and ORR activity with a half-wave potential of 0.83 V, close to that of 20 wt% Pt/C. Theoretical computations reveal that the p-band center for C-2p orbit in N,P-C-1000 has higher interaction strength with the intermediates, thus reducing the overall reaction energy barrier. The N,P-C-1000 assembled primary ZAB can attain a large peak power density of 121.9 mW cm−2 and a steady discharge platform of ∼1.20 V throughout 120 h. Besides, when served as the cathodic catalyst in a solid-state ZAB, the battery shows flexibility, conspicuous open circuit potential (1.423 V), and high peak power density (85.8 mW cm−2). Our findings offer a strategy to tune the intrinsic structure of carbon-based catalysts for improved electrocatalytic performance and shed light on future catalysts design for energy storage technologies beyond batteries. [ABSTRACT FROM AUTHOR]

In this work, a hollow tubule Bi 0.8 Ca 0.2 FeO 3– δ (BCF-T) cathode was synthesized using the metal nitrate impregnation method, with absorbent cotton serving as the template. The phase composition, electrocatalytic activity performance, oxygen reduction reaction (ORR) processes, and CO 2 tolerance of the BCF-T cathode are systematically studied. Compared with ordinary powder BCF (BCF–P) cathode, the BCF-T cathode presents outstanding electrocatalytic activity for ORR. The polarization resistance of the BCF-T cathode is 0.06 Ω cm2 at 700 °C, and the peak power density (PPD) of the single cell is 1042 mW cm−2 at 800 °C. The unique tubular microstructure of BCF-T is beneficial for enhance the oxygen transport property and the ORR activity of the electrode. Moreover, the BCF-T electrode also shows excellent CO 2 tolerance and chemical stability after 10% CO 2 treatment at 700 °C for 10 h. These features indicates that the tubule electrode with superior electrocatalytic activity and CO 2 tolerance might provide an effective strategy to design promising cathode catalysts for SOFCs. • A hollow tubule Bi 0.8 Ca 0.2 FeO 3- δ (BCF-T) cathodes are developed for SOFCs. • The polarization resistance of the BCF-T cathode is 0.06 Ω cm2 at 700 °C. • Maximum power density of single cell with BCF-T cathode reaches 1042 mW cm−2 at 800 °C. • BCF-T cathode shows outstanding CO 2 tolerance and chemical stability. [ABSTRACT FROM AUTHOR]

The energy crisis stems from increasing demand, diminishing fossil fuel reserves, and insufficient investment in renewable alternatives, posing a profound threat to global energy security and environmental sustainability. Fuel cells offer promise as a solution to the energy crisis and the integration of two-dimensional carbon materials in fuel cell catalysts holds potential for enhancing efficiency, reducing costs, and improving the overall sustainability of fuel cell technologies. The new two-dimensional carbon form tetra-penta-octagonal-graphene and its boron doped derivative have been examined in this report for its applicability in the electrocatalytic oxygen reduction reaction for generation of electricity. The most favorable site for the reaction in the pristine specimen and the most favorable boron doping site have been carefully determined based on adsorption energy and formation energy, respectively. Projected density of states confirms a low density of states for the active site in both specimens. Boron doping causes a significant charge transfer from the primed site. The analysis of the four electron pathways along with the dioxygen adsorption step in the acidic medium has been conducted to gain a deeper understanding of the process. In both systems, the formation of the *O intermediate is associated with the highest Gibbs free energy change. The performance of the pristine material in the process has been found to support monotonically exothermic reaction with an overpotential of 0.622 V whereas the boron doped specimen presents very small barrier for the dioxygen adsorption step followed by monotonically exothermic reaction steps with overpotential 0.549 V. • A new sp2 stable 2D carbon allotrope TPO-graphene shows electrocatalytic activity. • Active site has lowest partial density of states at Fermi level. • Steps of ORR in four-electron pathway in acidic medium are monotonically exothermic. • TPO-graphene has a overpotential of 0.622 V for the ORR process. • Boron doping creates ORR catalysis site with lowest partial density of states. • Boron doped TPO-graphene has a overpotential of 0.549 V for the ORR process. [ABSTRACT FROM AUTHOR]

Strain engineering is a promising approach to control the oxygen reduction reaction (ORR) kinetics of perovskite cathodes in solid oxide fuel cells (SOFCs). For multi-component oxide materials such as perovskite, there are two main strain effects: altering the surface reactivity and modifying the surface chemical composition. Our previous study (Energy Environ. Sci. 11 (2018) 71–77) showed that applying tensile strain enhances the oxygen exchange kinetics on SrTiFeO 3−δ (STF) surfaces by suppressing Sr segregation. However, the potential impact of changes in surface reactivity by strain on the oxygen exchange kinetics of STF remains unexplored yet. To address this gap, density functional theory (DFT) calculations are performed to evaluate the strain effect on oxygen incorporation on SrO and (Ti,Fe)O 2 (001) terminations of STF surfaces. The presence of surface vacancies is necessary for O 2 activation and dissociation. With the assistance of oxygen vacancies, O 2 incorporation is favorable on the (Ti,Fe)O 2 surface over the SrO surface. Tensile strain facilitates O 2 incorporation kinetics on the (Ti,Fe)O 2 surface, but its effect is weak on the SrO surface. Our results demonstrate that the enhanced oxygen surface exchange kinetics due to tensile strain in STF result not only from the inhibition of Sr segregation but also from an increase in O 2 incorporation. [Display omitted] • DFT study of O 2 incorporation on two terminated surfaces of SrTiFeO 3 (001). • Surface V O are vital for O 2 incorporation on both (Ti,Fe)O 2 and SrO surfaces. • Biaxial strain boosts O 2 incorporation on (Ti,Fe)O 2 , minimally affecting SrO. • This work elucidates the experimentally observed link between strain and surface oxygen exchange. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Dalton Transactions: An International Journal of Inorganic Chemistry." It includes a range of articles on various topics related to inorganic chemistry, such as electrocatalysts for water splitting, phosphors for backlight display applications, and metal-organic compounds in sensing and catalysis. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document provides a list of articles and their authors, along with images and permissions. [Extracted from the article]

The need for effective alternative energy sources and "green" industrial processes is a more crucial societal topic than ever. In this context, mastering oxygen reduction reactions (ORRs) is a key step to develop fuel cells or to propose alternatives to energy-intensive setups such as the anthraquinone process for hydrogen peroxide production. Achieving this goal using bio-inspired metal complexes based on abundant and non-toxic elements could provide an environmentally friendly option. Given the prevalence of Cu-containing active sites capable of reductive activation of dioxygen in nature, the development of Cu-based catalysts for the ORR thus appears to be a relevant approach. We herein report the preparation, full characterization and (TD)DFT investigation of a new dinuclear mixed-valent copper complex 6 exhibiting a Cu2S core and a bridging triflate anion. Its ORR activity was compared with that of its parent catalyst 1. Two types of solvents were used, acetonitrile and acetone, and various catalyst/Me8Fc (electron source) ratios were tested. Our results highlight a counterintuitive solvent effect for 1 and a drastic drop in the activity for 6 in coordinating acetonitrile together with the modification of its chemical structure. [ABSTRACT FROM AUTHOR]

Dual‐atom catalysts (DACs) have been proposed to break the limitation of single‐atom catalysts (SACs) in the synergistic activation of multiple molecules and intermediates, offering an additional degree of freedom for catalytic regulation. However, it remains a challenge to synthesize DACs with high uniformity, atomic accuracy, and satisfactory loadings. Herein, we report a facile cascade synthetic strategy for DAC via precise electrostatic interaction control and neighboring vacancy construction. We synthesized well‐defined, uniformly dispersed dual Fe sites which were connected by two nitrogen bonds (denoted as Fe‐N2‐Fe). The as‐synthesized DAC exhibited superior catalytic performances towards oxygen reduction reaction, including good half‐wave potential (0.91 V), high kinetic current density (21.66 mA cm−2), and perfect durability. Theoretical calculation revealed that the DAC structure effectively tunes the oxygen adsorption configuration and decreases the cleavage barrier, thereby improving the catalytic kinetics. The DAC‐based zinc‐air batteries exhibited impressive power densities of 169.8 and 52.18 mW cm−2 at 25 °C and −40 °C, which is 1.7 and 2.0 times higher than those based on Pt/C+Ir/C, respectively. We also demonstrated the universality of our strategy in synthesizing other M‐N2‐M DACs (M=Co, Cu, Ru, Pd, Pt, and Au), facilitating the construction of a DAC library for different catalytic applications. [ABSTRACT FROM AUTHOR]

Decoration of an axial coordination ligand (ACL) on the active metal site is a highly effective and versatile strategy to tune activity of single‐atom catalysts (SACs). However, the regulation mechanism of ACLs on SACs is still incompletely known. Herein, we investigate diversified combinations of ACL‐SACs, including all 3d–5d transition metals and ten prototype ACLs. We identify that ACLs can weaken the adsorption capability of the metal atom (M) by raising the bonding energy levels of the M−O bond while enhancing dispersity of the d orbital of M. Through examination of various local configurations and intrinsic parameters of ACL‐SACs, a general structure descriptor σ is constructed to quantify the structure–activity relationship of ACL‐SACs which solely based on a few key intrinsic features. Importantly, we also identified the axial ligand descriptor σACL, as a part of σ, which can serve as a potential descriptor to determine the rate‐limiting steps (RLS) of ACL‐SACs in experiment. And we predicted several ACL‐SACs, namely, CrN4‐, FeN4‐, CoN4‐, RuN4‐, RhN4‐, OsN4‐, IrN4‐ and PtN4‐ACLs, that entail markedly higher activities than the benchmark catalysts of Pt and IrO2 for oxygen reduction reaction and oxygen evolution reaction, respectively, thereby supporting that the general descriptor σ can provide a simple and cost‐effective method to assess efficient electrocatalysts. [ABSTRACT FROM AUTHOR]

The electro‐Fenton (EF) process is an advanced oxidation technology with significant potential; however, it is limited by two steps: generation and activation of H2O2. In contrast to the production of H2O2 via the electrochemical two‐electron oxygen reduction reaction (ORR), the electrochemical three‐electron (3e−) ORR can directly activate molecular oxygen to yield the hydroxyl radical (⋅OH), thus breaking through the conceptual and operational limitations of the traditional EF reaction. Therefore, the 3e− ORR is a vital process for efficiently producing ⋅OH in situ, thus charting a new path toward the development of green water‐treatment technologies. This review summarizes the characteristics and mechanisms of the 3e− ORR, focusing on the basic principles and latest progress in the in situ generation and efficient utilization of ⋅OH through the modulation of the reaction pathway, shedding light on the rational design of 3e− ORR catalysts, mechanistic exploration, and practical applications for water treatment. Finally, the future developments and challenges of efficient, stable, and large‐scale utilization of ⋅OH are discussed based on achieving optimal 3e− ORR regulation and the potential to combine it with other technologies. [ABSTRACT FROM AUTHOR]

Use of Intra-Aortic Balloon Pump (IABP) in combination with Impella has been described as an alternative strategy for mechanical circulatory support (MCS) in patients with cardiogenic shock (CS). We provide a systematic review aimed to explore the effectiveness of this paired MCS approach. We conducted a comprehensive systematic search in MEDLINE, Scopus, and Cochrane databases to identify all studies that investigated dual MCS with IABP and Impella. Our search strategy identified 12 articles, including 1 randomized controlled trial, 1 retrospective study, 1 case series, 7 case report and 2 animal studies. Rationale for this combined MCS strategy stems from an observed reduction in myocardial oxygen demand/supply ratio compared to the use of each device alone, without determining significant variations in left ventricular work. Nonetheless, this combined approach also leads to a 30–40 % decline in Impella flow, increasing the risk of bleeding, Impella displacement, as well as triggering positioning and pressure alarms. Additionally, hemolytic risk data yielded inconclusive results. Importantly, there were no notable disparities in mortality rates when comparing the combined strategy to the use of each device individually. At the current state-of-the-art, there are no conclusive data demonstrating net clinical benefits of combining Impella with IABP. Considering the substantial risks of morbidity associated, we recommend against its use in clinical practice. [Display omitted] • MCS combination is an interesting strategy but need a strong rationale due to side effects. • Impella functioning is severely worsened when combined with IABP. • Hemodynamic benefit of IABP and Impella combination does not justify increased risk. • Expansion of registries on major outcomes is needed to examine dual MCS strategies. [ABSTRACT FROM AUTHOR]

Coordination environment engineering is developed to synthesize Fe SA /NSC catalysts with the tailored N, S co-coordinated Fe atomic site. [Display omitted] • The Fe-N 3 S active site with the optimized electronic structure is constructed. • S doping promotes the OH* desorption, thus leading to enhanced kinetics process. • The catalyst displays impressive ORR activity in both alkaline and acidic mediums. • The catalyst exhibits excellent performance in Zn-air batteries and fuel cells. Atomically dispersed iron–nitrogen-carbon (FesbndNsbndC) materials have been considered ideal catalysts for the oxygen reduction. Unfortunately, designing and adjusting the electronic structure of single-atom Fe sites to boost the kinetics and activity still faces grand challenges. In this work, the coordination environment engineering is developed to synthesize the Fe SA /NSC catalyst with the tailored N, S co-coordinated Fe atomic site (Fe-N 3 S site). The structural characterizations and theoretical calculations demonstrate that the incorporation of sulfur can optimize the charge distribution of Fe atoms to weaken the adsorption of OH* and facilitate the desorption of OH*, thus leading to enhanced kinetics process and intrinsic activity. As a result, the S-modified Fe SA /NSC exhibits outstanding catalytic activity with the half-wave potentials (E 1/2) of 0.915 V and 0.797 V, as well as good stability, in alkaline and acidic electrolytes, respectively. Impressively, the excellent performance of Fe SA /NSC is further confirmed in Zn-air batteries (ZABs) and fuel cells, with high peak power densities (146 mW cm−2 and 0.259 W cm−2). [ABSTRACT FROM AUTHOR]

[Display omitted] Production of C 2 chemicals (such as C 2 H 4 , C 2 H 5 OH, etc.) from CO 2 electroreduction reaction (CO 2 ER) has been regarded as a promising route to solve the environmental problems and energy crisis. In this work, mesoporous Cu 2 O microspheres of ca. 700 nm diameter size with low crystallinity were fabricated to enable efficient conversion of CO 2 to C 2 chemicals by electrocatalytic reduction. It is revealed that compared with bulk Cu 2 O, the obtained mesoporous Cu 2 O microspheres have larger surface area, more grain boundaries and defects (unsaturated coordination sites), which facilitate the adsorption and stabilization of the important intermediates, such as *CO, on the route to C 2 chemicals formation. As a result, the Faraday efficiency (FE) of C 2 products reaches as high as 82.6 % and 78.5 % in an H-cell and a flow cell, respectively. In situ Raman and FT-IR spectra reveal that during CO 2 ER test there exists abundant *CO on the mesoporous Cu 2 O surface, thus increasing the opportunity of C C coupling. And the high coverage of *CO on catalyst surface during CO 2 ER protects and stabilizes the oxidation state of Cu species. This work demonstrates an effective strategy to introduce mesoporous structures and decreased crystallinity for improving the performance of CO 2 ER to C 2 products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mg-Ni dual atomic catalysts are constructed for eCO 2 RR to produce syngas. • Faradaic efficiency is close to ∼100 % exhibiting the excellent selectivity. • The controllable H 2 /CO ratio is achieved by tuning Ni content. • Synergistic effect to win instead of each species doing its own job by DFT calculations. Electrochemical carbon dioxide reduction reaction (eCO 2 RR) to generate syngas is an appealing strategy for CO 2 net reduction. However, it suffers from the inferior faradaic efficiency (FE), selectivity, and difficult modulation of hydrogen/carbon monoxide (H 2 /CO) ratio. To address these issues, a series of magnesium-nickel (Mg-Ni) dual atomic catalysts with different Ni contents are fabricated on the nitrogen-doped carbon matrix (MgNi X -NC DACs) by one-step pyrolysis. MgNi 5 -NC electrocatalyst generates 0.51–0.79 H 2 /CO ratios in a potential range of −0.6 to −1.0 V vs. reversible hydrogen electrode (RHE) and the total FE reaches 100 % with good stability. While a wider range of H 2 /CO (0.95–4.34) is achieved for MgNi 3 -NC electrocatalyst in the same overpotential range, which is suitable for typical downstream thermochemical reactions. Introduction of Ni species accelerates the generation of CO, however, there is much less influence on the H 2 production as compared with Mg-based single atomic electrocatalyst. According to the experimental results and density functional theory (DFT) calculations, the synergistic effect between Mg and Ni achieves the satisfied results rather than each one fulfill its own duty for selective producing H 2 and CO, respectively. This work introduces a feasible approach to develop atomic catalysts on main group metal for more controllable CO 2 RR. [ABSTRACT FROM AUTHOR]

Fe-based double perovskites represent a significant category of cobalt-free materials and exhibit promise as cathodes for solid oxide fuel cells (SOFCs) because of their lower thermal expansivity and reduced cost. However, they often encounter challenges associated with poor oxygen reduction reactivity stemming from intrinsic low electronic and oxygen-ion conductivity. In this investigation, Ca was introduced as a dopant for the first time to improve the electrochemical properties of PrBaFe 2 O 5+ δ (PBFO). The findings unveiled effective adjustments in the formation of oxygen vacancy by introducing Ca into PBFO. Therefore, the oxygen adsorption, dissociation, and charge transfer processes were modulated considerably. At 800 °C, PrBa 0.9 Ca 0.1 Fe 2 O 5+ δ (PBCFO) exhibited a R p of 0.027 Ω cm2, representing a 78.1 % reduction in comparison with PBFO. Concurrently, the output power density of the PBCFO increased by 17.3 %. These results underscore the potential of Ca doping to elevate the ORR kinetics and CO 2 tolerance of PBFO. [ABSTRACT FROM AUTHOR]

This work presents simple post-treatment methods to selectively and partially remove the Pd core of Pd–Pt core–shell (Pt@Pd/C) catalysts. The proton exchange membrane fuel cell with the post-treated Pt@Pd/C cathode (Pt loading: 0.10 mg·cm−2) delivers an impressive peak power density of 1.2 W·cm−2. The partial removal of Pd core endows an ultrahigh oxygen reduction reaction (ORR) mass activity of 0.32 A·mgPGM−1 when normalized to the platinum group metal (PGM) mass, or equivalently 0.55 A·mgPt−1 at 0.9 V measured in a fuel cell. The post-treatment thickens the Pt shells and mitigates the Pd dissolution during potential cycling. As a result, the post-treated core–shell catalyst demonstrates superior durability in ORR mass activity and polarization power density retention than untreated core–shell catalyst and benchmark Pt/C. In-situ inductively coupled plasma-mass spectrometry (ICP-MS) results highlight that the amount of dissolved Pd in post-treated core–shell catalyst is 17-times lower than that of the untreated one. Our findings highlight the importance of structural tuning of catalysts in enhancing their mass activity and durability. [ABSTRACT FROM AUTHOR]

Bifunctional catalysts for oxygen evolution reduction (OER) and oxygen reduction reaction (ORR) are key renewable energy technologies including metal–air batteries and water splitting. In this work, a solid-state sintering approach was employed to prepare spinel-structured bimetallic oxides Co2GeO4 and Ni2GeO4 with remarkable bifunctional catalytic activity. Compared to Ni2GeO4 and Co3O4, Co2GeO4 demonstrates a larger density of oxygen vacancies, leading to an increased abundance of active sites and superior OER and ORR activities. Electrochemical measurements were carried out in alkaline media, the material requiring a mere overpotential of 263 mV to attain a current density of 10 mA cm−2. Moreover, Co2GeO4 exhibited exceptional stability, maintaining a stable potential for 40 h at a current density of 1 mA cm−2. The calculation revealed that the high stability is attributed to the robust Ge-O bonds, which stabilize the Ge-O4 tetrahedrons within the spinel framework. This study possesses significant potential in guiding the development of highly efficient bifunctional electrocatalysts for both OER and ORR. [ABSTRACT FROM AUTHOR]

Modulating the spin states of FeN4 moieties is critical for enhancing the electrocatalytic oxygen reduction reaction (ORR). In this study, Ti4N3Clx and Ti4N3Ox MXenes are synthesized and functionalized with iron phthalocyanine (FePc) to form model catalysts with well‐defined FeN4‐Cl‐Ti and FeN4‐O‐Ti structures, respectively. The FeN4‐Cl‐Ti structure, formed within the Ti4N3Clx/FePc composite, enables precise modulation of FeN4 spin states from low to intermediate spin, significantly enhancing ORR performance. In contrast, the FeN4‐O‐Ti structure in Ti4N3Ox/FePc shows less effective spin state modulation, leading to comparatively lower ORR activity. Compared to FePc and Ti4N3Ox/FePc, Ti4N3Clx/FePc demonstrates superior electrochemical performance, with an ORR half‐wave potential of +0.91 V versus RHE and doubled power densities in Zn–air batteries (214.5 mW cm−2). Theoretical studies confirm that the intermediate spin states induced by the weak‐field ligand‐modified FeN4‐Cl‐Ti structure in Ti4N3Clx/FePc facilitate electron filling in the antibonding orbital composed of Fe 3dz2 and O2 π* orbitals, greatly enhancing O₂ activation and ORR activity. These findings underscore the superior catalytic properties of FeN4‐Cl‐Ti compared to FeN4‐O‐Ti, advancing the understanding of spin state‐related catalytic mechanisms and guiding the design of high‐performance ORR catalysts. [ABSTRACT FROM AUTHOR]

Integrating active sites for oxygen reduction and evolution reactions (ORR and OER) is pivotal for advancing bifunctional oxygen electrodes. Addressing the geometric/electronic properties of these sites is essential to disrupt the linear scaling relationship between the adsorption and desorption of complex intermediates. Herein, a proof‐of‐concept is presented for constructing asymmetric trinuclear sites employing both composition‐ and size‐based asymmetric coupling strategies. These sites comprise ORR‐active Fe single atom (FeSA), OER‐active atomically clustered Fe species (FeAC), and NiSA sites as modulators. This FeAC‐SA‐NiSA@N‐doped carbon exhibits excellent bifunctional catalytic activities, with a narrow potential gap of 0.661 V between an ORR half‐wave potential of 0.931 V and an OER potential of 1.592 V at 10 mA cm−2. The Zn‐air battery employing this material achieves a peak power density of 293 mW cm−2, a specific capacity of 748 mAh gZn−1, and remarkable stability. Experimental findings and theoretical simulations reveal that NiSA sites induced strong electronic coupling among the trinuclear centers, facilitating charge redistribution and optimizing the adsorption and desorption barriers for intermediates. This enhances the rapid release of *OH during ORR and the efficient transformation from *O to *OOH during OER. This study presents a novel strategy for developing robust bifunctional oxygen electrodes. [ABSTRACT FROM AUTHOR]

This work reports the high catalytic performances of Cu–Co–O/N-doped carbon materials toward the hydrogenation reduction and advanced oxidation reactions of 4-nitrophenol (PNP). By incorporating Cu2+ and Co2+ with atomic ratios from 1 : 9 to 1 : 4, 1 : 2, 1 : 1, 9 : 1, and 19 : 1, catalysts prepared at 500 °C in air via sol–gel method demonstrated superior catalytic ability toward the two reactions than those prepared at 600 °C. The crystalline phase of the catalyst with an atomic ratio of 1 : 1 was determined to be CuO and Cu0.92Co2.08O4, and a reaction time of 4.5 min and activity parameter of 300 s−1 g−1 could be obtained for the reduction reaction of PNP over this CuO–Cu0.92Co2.08O4/N-doped carbon material when the NaBH4 : PNP molar ratio was 100 : 1. The activity parameters were 300 s−1 g−1 and 294 s−1 g−1 for catalysts with Cu2+ : Co2+ atomic ratios of 1 : 9 and 19 : 1, respectively, and the main contribution toward the catalytic performance is discussed in terms of oxygen vacancies or synergistic effects. The CuO–Cu0.92Co2.08O4/N-doped carbon material also had desirable catalytic ability toward the advanced oxidation reaction of PNP using peroxymonosulfate (PMS) as an oxidation agent, whereby an activity parameter of 51.7 s−1 g−1 could be obtained when the PMS : PNP molar ratio was 14 : 1. Our results provide new insights into promoting the catalytic property of transitional oxide-based catalysts. [ABSTRACT FROM AUTHOR]

The current study describes a facile, time-effective and cost-viable synthesis of highly efficient Fe–N–C catalysts tailored for PEMFC. In this work, three different Fe–N–C catalysts for oxygen reduction reaction (ORR) have been synthesized by pyrolyzing different organic molecules in a microwave machine. The catalytic materials have been characterized using advanced techniques such as SEM, TEM, EDS, XPS, and BET analysis to elucidate their morphological, compositional, and surface properties. The fabricated materials i.e. Fe–N–C-Urea (Fe–N–C–U), Fe–N–C- Para- Phenylene Diamine (Fe–N–C- p PD) and Fe–N–C-5-Amino-1-(4′-Aminophenyl)-1,3,3-Trimethylindane (Fe–N–C-AAT) exhibit remarkable peak power densities, reaching as high as 0.96 W cm−2, 0.77 W cm−2 and 0.90 W cm−2, respectively, at a flow rate of 0.4 L min−1 of oxygen and 0.2 L min−1 of hydrogen, keeping the temperature constant at 80 °C. The current work emphasizes the deployment of facile and rapid synthetic protocol coupled with exploiting ingenious organic molecules and avoiding the application of any solvent. [Display omitted] • Adopt microwave-assisted pyrolysis strategy to synthesize distinct Fe–N–C electrocatalysts. • Fe–N–C–U and Fe–N–C-AAT exhibits eminent ORR activity in acidic medium. • The power density of Fe–N–C–U and Fe–N–C-AAT based PEMFC reaches 0.96 and 0.90 W cm−2, respectively. [ABSTRACT FROM AUTHOR]

Seawater electrolysis (SWE) is proposed to be a promising approach to green hydrogen (H2) production but its large‐scale deployment faces challenges because of the anodic competing chlorine evolution reaction (CER) and high energy consumption. To address these challenges, innovative hybrid SWE systems have recently emerged, able to mitigate the interference of CER and substantially reduce the electrical energy needed. Herein, the preparation of 2D layered PtTe nanosheets (e‐PtTe NSs) using the liquid‐phase exfoliation method is reported, which show outstanding electrocatalytic performance for the hydrogen evolution (HER), hydrazine oxidation (HzOR), and oxygen reduction reactions (ORR) in seawater. Using e‐PtTe NSs as trifunctional catalysts, two hybrid SWE systems are demonstrated: 1) a hydrazine‐assisted acid‐alkaline dual‐electrolyte seawater electrolyzer enabled by a bipolar membrane (BPM‐OHzSWE), which can simultaneously produce H2 and generate electricity through harvesting the electrochemical neutralization energy and leveraging the advantage of the HzOR over the oxygen evolution reaction (OER) in terms of anodic potentials; 2) a hydrazine‐assisted SWE system powered by a direct hydrazine fuel cell (DHzFC), which can realize self‐powered H2 production. These novel hybrid SWE systems show substantial promise for energy‐saving and cost‐effective production of H2 from seawater. [ABSTRACT FROM AUTHOR]

Conventional strategies for highly selective and active hydrogen peroxide (H2O2) electrosynthesis primarily focus on catalyst design. Electrocatalytic reactions take place at the electrified electrode–electrolyte interface. Well‐designed electrolytes, when combined with commercial catalysts, can be directly applied to high‐efficiency H2O2 electrosynthesis. However, the role of electrolyte components is equally crucial but is significantly under‐researched. In this study, anionic surfactant n‐tetradecylphosphonic acid (TDPA) and its analogs are used as electrolyte additives to enhance the selectivity of the two‐electron oxygen reduction reaction. Mechanistic studies reveal that TDPA assembled over the electrode–electrolyte interface modulates the electrical double‐layer structure, which repels interfacial water and weakens the hydrogen‐bond network for proton transfer. Additionally, the hydrophilic phosphonate moiety affects the coordination of water molecules in the solvation shell, thereby directly influencing the proton‐coupled kinetics at the interface. The TDPA‐containing catalytic system achieves a Faradaic efficiency of H2O2 production close to 100% at a current density of 200 mA cm−2 using commercial carbon black catalysts. This research provides a simple strategy to enhance H2O2 electrosynthesis by adjusting the interfacial microenvironment through electrolyte design. [ABSTRACT FROM AUTHOR]

Photocatalytic synthesis of H2O2 is an advantageous and ecologically sustainable alternative to the conventional anthraquinone process. However, achieving high conversion efficiency without sacrificial agents remains a challenge. In this study, two covalent organic frameworks (COF−O and COF−C) were prepared with identical skeletal structures but with their pore walls anchored to different alkyl chains. They were used to investigate the effect of the chemical microenvironment of pores on photocatalytic H2O2 production. Experimental results reveal a change of hydrophilicity in COF−O, leading to suppressed charge recombination, diminished charge transfer resistance, and accelerated interfacial electron transfer. An apparent quantum yield as high as 10.3 % (λ=420 nm) can be achieved with H2O and O2 through oxygen reduction reaction. This is among the highest ever reported for polymer photocatalysts. This study may provide a novel avenue for optimizing photocatalytic activity and selectivity in H2O2 generation. [ABSTRACT FROM AUTHOR]

Carbon‐based materials have been utilized as effective catalysts for hydrogen peroxide electrosynthesis via two‐electron oxygen reduction reaction (2e ORR), however the insufficient selectivity and productivity still hindered the further industrial applications. In this work, we report the Fe−O4 motif activated graphitic carbon material which enabled highly selective H2O2 electrosynthesis operating at high current density with excellent anti‐poisoning property. In the bulk production test, the concentration of H2O2 cumulated to 8.6 % in 24 h and the corresponding production rate of 33.5 mol gcat−1 h−1 outperformed all previously reported materials. Theoretical model backed by in situ characterization verified α‐C surrounding the Fe−O4 motif as the actual reaction site in terms of thermodynamics and kinetics aspects. The strategy of activating carbon reaction site by metal center via oxo‐bridge provides inspiring insights for the rational design of carbon materials for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Photocatalytic synthesis of H2O2 is an advantageous and ecologically sustainable alternative to the conventional anthraquinone process. However, achieving high conversion efficiency without sacrificial agents remains a challenge. In this study, two covalent organic frameworks (COF−O and COF−C) were prepared with identical skeletal structures but with their pore walls anchored to different alkyl chains. They were used to investigate the effect of the chemical microenvironment of pores on photocatalytic H2O2 production. Experimental results reveal a change of hydrophilicity in COF−O, leading to suppressed charge recombination, diminished charge transfer resistance, and accelerated interfacial electron transfer. An apparent quantum yield as high as 10.3 % (λ=420 nm) can be achieved with H2O and O2 through oxygen reduction reaction. This is among the highest ever reported for polymer photocatalysts. This study may provide a novel avenue for optimizing photocatalytic activity and selectivity in H2O2 generation. [ABSTRACT FROM AUTHOR]

Isolated Fe–Nx sites coupled with Fe3C nanoparticles co-embedded in N-doped porous carbon were fabricated using polyethylene terephthalate wastes as carbon sources. Benefiting from the synergistic effect between Fe–Nx sites and Fe3C, and the hierarchical porous structure, the catalyst exhibits outstanding ORR performance, realizing the concept of turning trash into treasure. [ABSTRACT FROM AUTHOR]

The development of green and environmentally friendly synthesis methods of electrocatalysts is a crucial aspect in decarbonizing energy generation. In this study, eco‐friendly mechanochemical synthesis of perovskite metal oxide‐carbon black composites is proposed using different conditions and additives such as KOH. Furthermore, the optimization of ball milling conditions, including time and rotational speed, is studied. The mechanochemical synthesis in solid‐state conditions without additives produces electrocatalysts that exhibit the highest bifunctional electrochemical activity towards both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Moreover, this synthesis demonstrates a lower Environmental Impact Factor (E‐factor), indicating its greener nature, and due to its simplicity, it has a great potential for scalability. The obtained bifunctional electrocatalysts have been tested in a rechargeable zinc‐air battery (ZAB) for 22 h with similar performance compared to the commercial catalyst (Pt/C) at significantly lower cost. These promising findings are attributed to the enhanced interaction between the perovskite metal oxide and carbon material and the improved dispersion of the perovskite metal oxide on the carbon materials. [ABSTRACT FROM AUTHOR]

Reasonable design of low‐cost, high‐efficiency and stable bifunctional oxygen electrocatalysts is of great significance to improve the reaction efficiency of Zn‐air batteries, which is still a huge challenge. Here, we report a highly efficient bifunctional oxygen electrocatalyst with three‐dimensional (3D) N‐doped graphene network‐supported cobalt and cobalt oxide nanoparticles (Co/CoO‐NG), which can be in situ synthesized by inducing metal ions on metal plates via graphene oxide as an inducer. This 3D network structure and open active center show excellent bifunctional oxygen electrocatalytic activity under alkaline conditions, and can be used as an air electrode in rechargeable Zn‐air batteries, with significantly better power density (244.28 mW cm−2) and stability (over 340 h) than commercial Pt/C+RuO2 mixtures. This work is conducive to advancing the practical application of graphene‐based materials as air electrodes for rechargeable zinc‐air batteries. [ABSTRACT FROM AUTHOR]

Over the past decades, CO2 greenhouse emission has been considerably increased, causing global warming and climate change. Indeed, converting CO2 into valuable chemicals and fuels is a desired option to resolve issues caused by its continuous emission into the atmosphere. Nevertheless, CO2 conversion has been hampered by the ultrahigh dissociation energy of C=O bonds, which makes it thermodynamically and kinetically challenging. From this prospect, photocatalytic approaches appear promising for CO2 reduction in terms of their efficiency compared to other traditional technologies. Thus, many efforts have been made in the designing of photocatalysts with asymmetric sites and oxygen vacancies, which can break the charge distribution balance of CO2 molecule, reduce hydrogenation energy barrier and accelerate CO2 conversion into chemicals and fuels. Here, we review the recent advances in CO2 hydrogenation to C1 and C2 products utilizing photocatalysis processes. We also pin down the key factors or parameters influencing the generation of C2 products during CO2 hydrogenation. In addition, the current status of CO2 reduction is summarized, projecting the future direction for CO2 conversion by photocatalysis processes. [ABSTRACT FROM AUTHOR]

Photocatalytic synthesis of H2O2 is an advantageous and ecologically sustainable alternative to the conventional anthraquinone process. However, achieving high conversion efficiency without sacrificial agents remains a challenge. In this study, two covalent organic frameworks (COF−O and COF−C) were prepared with identical skeletal structures but with their pore walls anchored to different alkyl chains. They were used to investigate the effect of the chemical microenvironment of pores on photocatalytic H2O2 production. Experimental results reveal a change of hydrophilicity in COF−O, leading to suppressed charge recombination, diminished charge transfer resistance, and accelerated interfacial electron transfer. An apparent quantum yield as high as 10.3 % (λ=420 nm) can be achieved with H2O and O2 through oxygen reduction reaction. This is among the highest ever reported for polymer photocatalysts. This study may provide a novel avenue for optimizing photocatalytic activity and selectivity in H2O2 generation. [ABSTRACT FROM AUTHOR]

Photocatalytic synthesis of H2O2 is an advantageous and ecologically sustainable alternative to the conventional anthraquinone process. However, achieving high conversion efficiency without sacrificial agents remains a challenge. In this study, two covalent organic frameworks (COF−O and COF−C) were prepared with identical skeletal structures but with their pore walls anchored to different alkyl chains. They were used to investigate the effect of the chemical microenvironment of pores on photocatalytic H2O2 production. Experimental results reveal a change of hydrophilicity in COF−O, leading to suppressed charge recombination, diminished charge transfer resistance, and accelerated interfacial electron transfer. An apparent quantum yield as high as 10.3 % (λ=420 nm) can be achieved with H2O and O2 through oxygen reduction reaction. This is among the highest ever reported for polymer photocatalysts. This study may provide a novel avenue for optimizing photocatalytic activity and selectivity in H2O2 generation. [ABSTRACT FROM AUTHOR]

N-doped WO3 anchored on porous carbon (N–WO3/PNC) was synthesized as an efficient oxygen reduction catalyst. The N doping reduced the overpotential of WO3 during oxygen reduction. N–WO3/PNC displayed a half-wave potential of 0.85 V. An N–WO3/PNC-based zinc–air battery displayed a high power density of 209.7 mW cm−2. [ABSTRACT FROM AUTHOR]

During the development of Zn-air batteries, designing an affordable, efficient and stable electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) presents a great challenge. Fe2O3 exhibits ORR and OER activities, but when used as a cathode material in Zn-air batteries, its activity requires further improvement. To achieve this goal, Ni is doped into Fe2O3 hexagonal nanorods, derived from a metal-organic framework (MOF) precursor, and further modified by N-doped carbon nanotubes. In ORR, its half-wave potential achieves 0.946 and 0.716 V in alkaline and neutral electrolytes, respectively. In OER, it requires 388 mV to obtain 10 mA cm-2 in an alkaline electrolyte. As illustrated by theoretical calculation, Ni-doping raises the d-band center of Fe2O3, which enhances its adsorption towards relevant oxygen species in electrocatalysis. This improves its ORR and OER activities. Based on these merits, the Zn-air battery is assembled with an alkaline electrolyte. At 10 mA cm-2, its specific capacity and energy density reach 819.8 mA h g-1 and 960.1 W h kg-1, respectively. This battery remains stable after a long time of charge and discharge. In neutral electrolytes, its promising discharge performance is also well retained. This work develops an effective approach to improve ORR and OER activities of Fe2O3-based cathode materials in Zn-air batteries. [ABSTRACT FROM AUTHOR]

The design and synthesis of efficient carbon‐based materials incorporating multifunctional sites is prospective technology for converting carbon dioxide (CO2) into high‐value chemicals. Here, nitrogen‐doped carbon catalysts (ZnAl‐NC) with bimetal zinc–aluminum sites were synthesized using nitrogen‐rich polyaniline (PANI) and ZnAl‐LDH through hydrothermal and in situ pyrolysis methods. ZnAl‐NC‐400, in the presence of tetrabutylammonium bromide (TBAB), exhibited excellent catalytic activity without solvent, achieving high yields (97.2% or 98.5%) in the cycloaddition of CO2 with propylene oxide (PO) under traditional or mild conditions. NH3‐TPD and CO2‐TPD results indicated that the enhanced catalytic activity resulted from the acid–base synergistic effect, involving Lewis acid sites from Zn and Al species and abundant Lewis base sites from the PANI matrix. The impact of calcination temperature on catalyst morphology, structure, and performance was investigated, along with catalyst recycling and adaptability to various epoxides. This work presents an efficient catalyst for CO2 conversion and suggests new approaches for designing catalytic sites in carbon‐based catalysts for CO2 capture and utilization. [ABSTRACT FROM AUTHOR]

Photocatalytic oxygen reduction to H2O2 based on g‐C3N4 has presented promising potential for sustainable solar‐fuel production. Yet tuning the timescale of hot electron's lifetime to effectively participate in the surface reactions remains challenging. Here, an electron‐deficient engineering strategy is developed by incorporating an electron‐deficient structure (EDS) with different conjugate regions into large conjugate‐heptazine framework (LCHF) of g‐C3N4 to steer hot electrons of the different timescales to effectively activate O2 for efficient photocatalytic H2O2 production. Femtosecond transientabsorption spectroscopy reveals that introducing EDS into LCHF can steer hot electron rapid transfer to the trapping sites of EDS and notably eliminate the deeply trapped electrons as well as enhance the shallow capture. It is demonstrated that pyromellitic dianhydride not only can tune the lifetime scale of hot electrons but also provide nonpolarized active sites to effectively activate O2 forming H2O2 with lower energy barrier via direct or stepwise 2e− pathways. This photocatalyst achieves an H2O2 yield rate of 25.40 mmol g−1 h−1, enabling an apparentquantumyield of 45.7% at 400 nm and a solar‐to‐chemical efficiency of 2.63%, outperforming the other reported photocatalysts. This work will shed light on the design of organic photocatalysts to tune hot electrons to effectively engage in the surface reaction. [ABSTRACT FROM AUTHOR]

A-site doping with Ca2+, Sr2+ for the cobalt-free BaFeO 3-δ -based cathode materials for proton-conducting ceramic fuel cells (PCFCs) is studied. The composite Ba 0·8 Ca 0·2 FeO 3-δ (BCF0.2)-BaZr 0.1 Ce 0·7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) and Ba 0·8 Sr 0·2 FeO 3-δ (BSF0.2)-BZCYYb electrode show polarization resistance (R p) of 0.156 Ω cm2 and 0.308 Ω cm2 at 700 °C, respectively. It is found that the Ca or Sr doping not only benefits oxygen vacancy formation and ion migration but also optimizes the surface oxygen reduction reaction (ORR) process. The density functional theory (DFT) calculations show that the Gibbs energies of *OOH and *OH intermediates are decreased, indicating an enhanced surface ORR. The PCFC with BCF0.2-BZCYYb composite cathode achieves the maximum power density of 299.75 mW cm−2 at 700 °C and shows good stability at 650 °C for 65 h under a constant voltage of 0.75 V. These findings suggest that the BCF0.2-BZCYYb has the potential to serve as cobalt-free cathode materials for PCFCs. [Display omitted] • Cobalt-free cubic perovskite Ba 1-x A x FeO 3-δ (A = Ca, Sr) materials are synthesized. • The Ba 0·8 Ca 0·2 FeO 3-δ -BZCYYb symmetrical cell shows low R p of 0.156 Ω cm2 at 700 °C. • DFT calculation reveals the ORR information on BaFeO 3-δ (110) surface doped with Ca or Sr. • The Gibbs energies of *OH and *OOH intermediates are decreased. [ABSTRACT FROM AUTHOR]

The non-noble bimetallic oxides have recently received more and more attention in electrocatalytic oxygen evolution reaction (OER) because of their potential to replace traditional precious metal catalysts, but the low activity and stability limit their wide application. Herein, the bimetallic oxide CoNiO 2 layers are decorated on the nitrogen-doped carbon nanofibers (NCF) through in situ grown of Ni(Co) bimetal organic frameworks (Ni(Co)-MOFs) on polyacrylonitrile nanofibers and subsequent pyrolysis process, so that a new NCF@CoNiO 2 electrocatalyst with one-dimensional (1D) core-shell structure is synthesized by structural induced effect of polyacrylonitrile nanofibers. Importantly, the unique interconnected network formed in the 1D NCF@CoNiO 2 electrocatalyst effectively improves electron mobility and mass transport capacity, thus exhibiting the glorious OER activity and long-term stability in alkaline solutions. As a result, the optimal NCF@CoNiO 2 -7 electrocatalyst requires an overpotential of 518 mV for OER at the current density of 100 mA cm−2, which is obvious lower than that of RuO 2 (633 mV) and CoNiO 2 /C-7 as a contrast sample (569 mV), respectively. This work opens up a new path for structural control of 1D bimetallic oxides to improve OER activity and stability. [Display omitted] • The NCF@CoNiO 2 electrocatalyst with a 1D core-shell structure is exploited. • 1D core-shell structure ascribes to structural induced effect of polymer nanofibers. • The NCF@CoNiO 2 exhibits superior OER activity and stability. • Interconnected network improves electron mobility and mass transport capacity. [ABSTRACT FROM AUTHOR]