Coulombic Efficiency Research Articles

Orderly Coating of Bilayer Polymer to Tailor Microenvironment for Efficient C−N Coupling Toward Highly Selective Urea Electrosynthesis

AbstractElectrosynthesis of urea from co‐reduction of carbon dioxide and nitrate is a promising alternative to the industrial process. However, the overwhelming existence of proton and nitrate as well as the insufficient supply of CO2 at the reaction interface usually result in complex product distributions from individual nitrate reduction or hydrogen evolution, instead of C−N coupling. In this work, we systematically optimize this microenvironment through orderly coating of bilayer polymer to specifically tackle the above challenges. Polymer of intrinsic microporosity is chosen as the upper polymer to achieve physical sieving, realizing low water diffusivity for suppressing hydrogen evolution and high gas permeability for smooth mass transfer of CO2 at the same time. Polyaniline with abundant basic amino groups is capable of triggering chemical interaction with acidic CO2 molecules, so that is used as the underlying polymer to serve as CO2 concentrator and facilitate the carbon source supply for C−N coupling. Within this tailored microenvironment, a maximum urea generation yield rate of 1671.6 μg h−1 mg−1 and a high Faradaic efficiency of 75.3 % are delivered once coupled with efficient electrocatalyst with neighboring active sites, which is among the most efficient system of urea electrosynthesis.

Synergistic N/F Dual-Doped MoC/C Catalyst Synthesized via Liquid Phase Plasma for Sustainable Ammonia Production.

NH3 is a versatile solution for the storage and distribution of sustainable energy, offering high energy density and promising applications as a renewable hydrogen carrier. However, electrochemical NH3 synthesis under ambient conditions remains challenging, such as low selectivity and efficiency, owing to the inertness of N≡N and competing reactions. In this study, a catalyst (MoC/NFC) comprising molybdenum carbide evenly dispersed on carbon doped with N and F heteroatoms was successfully synthesized using liquid-phase plasma. The MoC/NFC catalyst exhibited a maximum NH3 yield of 115 μg h-1 mg-1cat. with a faradaic efficiency of 1.15% at -0.7 V vs reversible hydrogen electrode in 0.1 M KOH electrolyte. Pyridinic- and pyrrolic-N atoms adjacent to the carbon pores served as active sites for N2 adsorption and enabled N2 triple bond cleavage. In addition, F doping contributed to N2 activation owing to the high electronegativity of 3.98, resulting in the attraction of more electrons. These findings demonstrate a significant advancement in the development of efficient catalysts for electrochemical ammonia synthesis, potentially paving the way for scalable and sustainable NH3 production methods that can support the growing demand for renewable energy storage solutions.

Biomimetic Elastic Single‐Atom Protrusions Enhance Ammonia Electrosynthesis

Electrocatalytic nitrogen (N2) reduction reaction (eNRR) is a promising route for sustainable ammonia (NH3) generation, but the eNRR efficiency is dramatically impeded by the sluggish reaction kinetics. Herein, inspired by the dynamic extension‐contraction of sea anemone tentacles in response to environmental changes, we propose a biomimetic elastic Mo single‐atom protrusion on vanadium oxide support (pSA Mo/VOH) electrocatalyst featuring a symmetry‐breaking Mo site and an elastic Mo−O4 pyramid for efficient eNRR. In‐situ spectroscopy and theoretical calculations reveal that the protruding Mo‐induced symmetry‐breaking structure optimizes the d electron filling of Mo, enhancing the back‐donation to the π* antibonding orbital, effectively polarizing the N≡N bond and reducing the barrier from *N2 to *N2H. Notably, the elastic Mo−O4 pyramidal structure of pSA Mo provides a dynamic Mo−O microenvironment during continuous eNRR processes. This optimizes the electronic structure of the Mo sites based on different reaction intermediates, enhancing the adsorption of various N intermediates and maintaining low barriers throughout the six‐step hydrogenation process. Consequently, the elastic pSA Mo/VOH exhibits an excellent NH3 yield rate of 50.71 ± 1.12 μg h−1 mg−1 and a Faradaic efficiency of 35.38 ± 1.03%, outperforming most electrocatalysts.

Fluorine-Doping Carbon-Modified Si/SiOx to Effectively Achieve High-Performance Anode.

To address the significant challenges encountered by silicon-based anodes in high-performance lithium-ion batteries (LIBs), including poor cycling stability, low initial coulombic efficiency (ICE), and insufficient interface compatibility, this work innovatively prepares high-performance Si/SiOx@F-C composites via in situ coating fluorine-doping carbon layer on Si/SiOx surface through high-temperature pyrolysis. The Si/SiOx@F-C electrodes exhibit superior LIB performance with a high ICE of 79%, exceeding the 71% and 43% demonstrated by Si/SiOx@C and Si/SiOx, respectively. These electrodes also show excellent rate performance, maintaining a capacity of 603 mAhg-1 even under a high current density of 5000 mAg-1. Notably, the Si/SiOx@F-C electrode sustains a high reversible capacity of 829 mAh g-1 at 1000mA g-1 over 1400 cycles, and 588 mAhg-1 at 3000 mAg-1 even over 2400 cycles, capacity retention of up to 82.12%. Comprehensive characterization and analysis of the fluorine-doped carbon layer reveal its role in enhancing electrical conductivity and preventing structural degradation of the material. The abundant fluorine in the coating layer significantly increases the LiF concentration in the solid electrolyte interface (SEI) film, improving interfacial compatibility and overall lithium storage performance. This method is both straightforward and effective, providing a promising blueprint for the broader application of Si-based anodes in advanced lithium batteries.

The Mechanism of Aluminum Deposition and Dendrite Growth on a Copper Substrate in Anode-Free Aluminum Batteries.

Given the critical demand for batteries with a high energy density and the global scarcity of lithium, anode-free aluminum batteries (AFABs) have attracted significant attention. AFABs utilize collectors instead of traditional anode metal foils, eliminating the need for anode materials and significantly enhancing the energy density of the batteries. However, the proliferation of aluminum dendrites might cause safety risks and reduce Coulombic efficiency, possibly impeding commercialization. This study employs molecular dynamics (MD) simulations to explore the deposition mechanisms of aluminum (Al) on copper (Cu) collectors and the dynamics of aluminum dendrite growth under nonhomogeneous deposition conditions. The results indicate that the surface properties of the Cu substrate significantly affect aluminum deposition, leading to more homogeneous and amorphous deposition on Cu(110) surfaces. However, the FCC structure of Al atoms on the Cu(111) surfaces exhibited the largest number. Strategically increasing the temperature and pressure can effectively prevent the formation of aluminum dendrites. The results are helpful for enhancing the battery cycle stability and the application of novel AFABs.

Evidence of Quasi-Na Metallic Clusters in Sodium Ion Batteries through In Situ X-Ray Diffraction.

Carbonaceous materials have been considered the most promising anode in sodium-ion batteries (SIBs) due to their low cost, good electrical conductivity, and structural stability. The main challenge of carbonaceous anodes prior to their commercialization is low initial coulomb efficiencies, derived from a lack of an efficient technique to reveal a fundamental comprehension of sodium storage mechanisms. Here, the direct observation of quasi-Na metallic clusters in carbonaceous anodes during cycling through in situ XRD is reported. By means of such a technique, a strong self-adsorption behavior forming quasi-Na metallic clusters is detected within a rationally designed highly defective ultrathin carbon nanosheets (HDCS) anode. Such a self-adsorption and crystalline system transformation mechanism in HDCS brings capacity retention about 100% after 1000 cycles at 1 A g-1. This work provides a new principle for designing high-performance carbon anodes for SIBs.

Ru-Incorporation-Induced Phase Transition in Co Nanoparticles for Low-Concentration Nitric Oxide Electroreduction to Ammonia at Low Potential.

Electrocatalytic reduction of nitric oxide (NO) to ammonia (NH3) represents a potential solution for improving the disrupted nitrogen cycle balance. Unfortunately, designing efficient electrocatalysts for NO reduction reaction (NORR) remains a notable challenge, especially at low concentrations. Herein, a displacement-alloying strategy is reported to successfully induce the phase transition of Co nanoparticles supported on carbon nanosheets from face-centered cubic (fcc) to hexagonal close-packed (hcp) structure through Ru incorporation. The obtained RuCo alloy with hcp phase structure (hcp-RuCo) exhibits apparent NORR activity with a record-high Faraday efficiency of 99.2% and an NH3 yield of 77.76µg h-1 mgcat -1 at -0.1V versus reversible hydrogen electrode at a NO concentration of 1vol %, surpassing Co nanoparticles with fcc phase structure and most reported catalysts. Density functional theory calculations reveal that the excellent NORR activity of hcp-RuCo can be attributed to the optimized electronic structure of Co site and lowered energy barrier of the potential rate-determining step through phase transition. Furthermore, the assembled Zn-NO battery using hcp-RuCo as the cathode achieves a power density of 2.33mW cm-2 and an NH3 yield of 45.94µg h-1 mgcat -1. This work provides a promising research perspective for low-concentration NO conversion.

Unique Oxygen-Bridged Nickel Atomic Pairs Efficiently Boost Electrochemical Reduction of Carbon Dioxide.

Benefiting from the synergism between adjacent bimetallic atoms, in comparison with single atom catalysts, the dual atom catalysts have displayed great potential in electrocatalytic CO2 reduction reaction (CO2RR). However, the further modulation of the electronic structure of dual atom sites to enhance CO2RR performance still remains a challenge. Herein, an atomically dispersed oxygen-bridged Ni2N6O/NC catalyst with unique Ni-O-Ni sites is successfully synthesized through the microwave pyrolysis of the supported mixture containing the dinuclear nickel phthalocyanine and glucose on N-doped carbon nanosheets. Experiments and density functional theory calculation reveal that the Ni-O-Ni sites can adsorb H+ from the KHCO3 electrolyte to in situ-form the unique Ni-OH-Ni sites without Ni─Ni bonding interaction, which effectively lowers the energy barrier towards the formation of *COOH from CO2. As a result, the Ni2N6OH/NC catalyst exhibits a 99.4% of CO Faradaic efficiency with a 32.4 mA·cm-2 of CO partial current density at -0.7V versus RHE in H-cell, much superior to the Ni2N6/NC with a Ni-Ni bonding interaction prepared by a similar procedure to that for Ni2N6O/NC but replacing microwave pyrolysis by a traditional heating process.

Iodine/Chlorine Multi-Electron Conversion Realizes High Energy Density Zinc-Iodine Batteries.

Aqueous zinc-iodine (Zn-I2) batteries are promising energy storage devices; however, the conventional single-electron reaction potential and energy density of iodine cathode are inadequate for practical applications. Activation of high-valence iodine cathode reactions has evoked a compelling direction to developing high-voltage zinc-iodine batteries. Herein, ethylene glycol (EG) is proposed as a co-solvent in a water-in-deep eutectic solvent (WiDES) electrolyte, enabling significant utilization of two-electron-transfer I+/I0/I- reactions and facilitating an additional reversibility of Cl0/Cl- redox reaction. Spectroscopic characterizations and calculations analyses reveal that EG integrates into the Zn2+ solvation structure as a hydrogen-bond donor, competitively binding O atoms in H2O, which triggers a transition from water-rich to water-poor clusters of Zn2+, effectively disrupting the H2O hydrogen-bond network. Consequently, the aqueous Zn-I2 cell achieves an exceptional capacity of 987 mAh gI2 -1 with an energy density of 1278Wh kgI2 -1, marking an enhancement of ≈300 mAh g-1 compared to electrolyte devoid of EG, and enhancing the Coulombic efficiency (CE) from 68.2% to 98.7%. Moreover, the pouch cell exhibits 3.72 mAh cm-2 capacity with an energy density of 4.52 mWh cm-2, exhibiting robust cycling stability. Overall, this work contributes to the further development of high-valence and high-capacity aqueous Zn-I2 batteries.

Three-dimensional Covalent Organic Framework with Dense Lithiophilic Sites as Protective Layer to Enable High-Performance Lithium Metal Battery.

Lithium (Li) metal batteries with remarkable energy densities are restrained by short lifetime and low Coulombic efficiency (CE), resulting from the accumulative Li dendrites and dead Li during cycling. Here, we prepared a new three-dimensional (3D) covalent organic framework (COF) with dense lithiophilic sites (heteoatom weight contents of 32.32wt%) as an anodic protective layer of Li metal batteries. The 3D COF was synthesized using a [6+4] synthesis strategy by inducing flexible 6-connected cyclotriphosphazene derivative aldehyde and 4-connected porphyrin-based tetraphenylamines. Both phosphazene and porphyrin rings in the COF served as electron-rich and lithiophilic sites, enhancing a homogeneous Li+ flux via 3D direction towards highly smooth and compact Li deposition. The Li/Por-PN-COF-Cu cells achieved a record average CE of 99.1% for 320 cycles with smooth Li deposition. Meanwhile, the abundant lithiophilic sites can promote fast Li+ transport with Li+ transference number of 0.87, enabling LiFePO4 full cell with stable stripping/plating processes even at a harsh rate of 5 C. Theoretical calculations revealed that the strong interaction force between Li+ and the COF facilitated the dissolution of Li+ from the electrolyte, and the low migration barrier of 1.08 eV indicated a favorable interaction between the Li+ ions and the π-electron system.

Molecular complex inspired design of an efficient copper(II)-containing robust porous polymers for electrochemical water oxidation

Homogeneous copper-bipyridine complexes have been reported as effective catalysts for water oxidation, demonstrating significant potential as alternatives to precious metal-based complexes. However, these complexes face long-term stability and product separation challenges similar to many homogeneous catalysts. Meanwhile, recent studies have underscored the potential of metalated polymer networks, which integrate the structural advantages of polymers with the functional benefits of metal species, making them highly attractive for various applications. Herein, we integrated copper-bipyridine units into porous polymer networks to overcome the limitations of copper-bipyridine complexes. We prepared a series of copper-incorporated polymers (TpBpy-Cux) for electrochemical water oxidation. The electrochemical properties of these polymers were tuned by varying the copper content, with TpBpy-Cu3 presenting the best performance among the samples studied. TpBpy-Cu3 demonstrated a low Tafel slope of 69 mV/decade, achieved a high Faradaic efficiency (FE) of 94 %, and exhibited exceptional stability over 1000 cyclic scans. This study offers insights into the design and optimization of metal-incorporated porous polymer networks building on the foundational understanding of their molecular counterparts for advanced catalytic applications.

Three‐dimensional Covalent Organic Framework with Dense Lithiophilic Sites as Protective Layer to Enable High‐Performance Lithium Metal Battery

Lithium (Li) metal batteries with remarkable energy densities are restrained by short lifetime and low Coulombic efficiency (CE), resulting from the accumulative Li dendrites and dead Li during cycling. Here, we prepared a new three‐dimensional (3D) covalent organic framework (COF) with dense lithiophilic sites (heteoatom weight contents of 32.32wt%) as an anodic protective layer of Li metal batteries. The 3D COF was synthesized using a [6+4] synthesis strategy by inducing flexible 6‐connected cyclotriphosphazene derivative aldehyde and 4‐connected porphyrin‐based tetraphenylamines. Both phosphazene and porphyrin rings in the COF served as electron‐rich and lithiophilic sites, enhancing a homogeneous Li+ flux via 3D direction towards highly smooth and compact Li deposition. The Li/Por‐PN‐COF‐Cu cells achieved a record average CE of 99.1% for 320 cycles with smooth Li deposition. Meanwhile, the abundant lithiophilic sites can promote fast Li+ transport with Li+ transference number of 0.87, enabling LiFePO4 full cell with stable stripping/plating processes even at a harsh rate of 5 C. Theoretical calculations revealed that the strong interaction force between Li+ and the COF facilitated the dissolution of Li+ from the electrolyte, and the low migration barrier of 1.08 eV indicated a favorable interaction between the Li+ ions and the π‐electron system.

Membrane-free Electrolysis Production of Hydrogen Peroxide on Low-Cost Metal-Free Electrocatalysts for Dye Degradation.

The efficient production of hydrogen peroxide (H2O2) solution was achieved by combining cathodic two-electron oxygen reduction (2e- ORR) and anodic two-electron water oxidation (2e- WOR) in two half-reaction cells. h-BN loaded on carbon fibers (h-BN@C) is prepared and employed as an anode material to catalyze 2e- WOR, while sulfonated commercial BP-2000 carbons (BP-2000-SO3H) were prepared as the cathode materials for 2e- ORR. In a 2 M KHCO3 solution, an overall Faradaic efficiency of 97% and a total H2O2 production rate of 1872 mmol g-1 h-1 over metal-free electrodes were accomplished in a membrane-free flow cell. The dilute H2O2 solution could be directly used to degrade cationic Rhodamine B or methyl orange and anionic methylene blue dyes in water. This work proved low-cost production of dilute H2O2 solution in simple membrane-free flow cells with single electrolyte and on-site utilization for efficient dye degradation.

Electrochemical Synthesis of Metasequoia-Like Reduced Graphene Oxide Coated Cobalt-Silver Catalyst for Stable and Efficient Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate (NO3 -) reduction to ammonia (NH3) is a green and efficient NH3synthesis technology. Metallic silver (Ag) is one of the well-known electrocatalysts for NO3 - reduction. However, under alkaline conditions, its poor water-splitting ability fails to provide sufficient protonic hydrogen required for NH3 synthesis, resulting in low NH3 selectivity. Additionally, metal catalysts are prone to leaching and oxidation during electrocatalysis, resulting in poor stability. Herein, cobalt (Co) into Ag (CoAg) catalyst is doped, which not only increases the NH3 selectivity by 34.4%, but also reduces the reduction potential by 0.1V. Meanwhile, reduced graphene oxide (rGO) as a protective "armor" is used to encapsulate the CoAg catalyst (rGO2.92@CoAg). The rGO2.92@CoAg catalyst shows excellent stability for over 300 hours (h) of continuous reaction. The Co and Ag contents in the rGO2.92@CoAg catalyst after continuous tests decreases by only 4.3% and 3.1%, respectively, which are much lower than those of the CoAg catalyst without the rGO (90.8%, 52.6%). Moreover, the rGO2.92@CoAg catalyst shows high Faradaic efficiency (99.3%) and NH3 yield rate (1.47mmol h-1 cm-2). Therefore, a high performance and strong stability rGO2.92@CoAg catalyst is obtained by Co doping and rGO coating, which provides theoretical basis for practical industrial application.

2D Graphene‐Like Carbon Coated Solid Electrolyte for Reducing Inhomogeneous Reactions of All‐Solid‐State Batteries

AbstractRecent studies have identified an imbalance between the electronic and ionic conductivities as the drivers of inhomogeneous reactions in composite cathodes, which cause the rapid degradation of all‐solid‐state battery (ASSB). To mitigate localized overcharge and utilize isolated active materials, the study proposes the coating of an argyrodite‐type Li6PS5Cl solid electrolyte (SE) with graphene‐like carbon (GLC@LPSCl), a 2D conductive material, to offer a continuous three‐dimensionally connected electron pathway within the composite cathode to facilitate ion mobility and promote homogeneous reactions. Despite reducing the content of the conducting agent, it is observed that the GLC@LPSCl cell exhibits high initial Coulombic efficiency and discharge capacity, reducing the inhomogeneous reactivity after 200 cycles compared with when ordinary conductive agents are deployed. Additionally, the presence of GLC@LPSCI surface suppresses the interfacial reaction between SE–cathode material, thus imparting the cell with excellent capacity retention (≈90%) after 200 cycles. Furthermore, the cell performance improves even after a fourfold increase in the cathode loading amount, demonstrating the criticality of a well‐developed continuous electron pathway to cell performance and highlighting the key role of ensuring a balance between the electron and ion conductivities in the development of high‐energy‐density and high‐power ASSBs.

Sodium‐Difluoro(oxalato)Borate‐Based Electrolytes for Long‐Term Cycle Life and Enhanced Low‐Temperature Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) are emerging as a promising alternative for next‐generation energy storage solutions, driven by the economic and environmental benefits of abundant sodium resources. A pivotal aspect of SIB advancement is the development of advanced electrolytes, which remains a formidable challenge. Herein, a facile and scalable synthesis method for low‐cost sodium‐difluoro(oxalato)borate (NaDFOB) is reported and explored its application as a standalone electrolyte salt for SIBs. The NaDFOB‐based ether electrolyte demonstrates exceptional electrochemical stability, solvent compatibility, and the unique capacity to form a dense, robust solid‐electrolyte interphase layer on electrode surfaces. As a result, the Na4Fe3(PO4)2P2O7 (NFPP) cathode with NaDFOB‐based electrolyte exhibits ultrahigh cycling stability with a remarkable capacity retention of 98.7% after 1000 cycles. Furthermore, an Ah‐level hard carbon (HC)//NFPP pouch cell using NaDFOB‐based ether electrolyte shows an impressive cycle life of 500 cycles, coupled with an average Coulombic efficiency of 99.9%. The pouch cells also maintain superior electrochemical performance across a broad temperature range from −40 to 60 °C, showcasing the electrolyte's versatility. This work contributes significant insights into the strategic design and application of innovative salts, paving the way for longer‐lasting SIBs with enhanced electrochemical performance.

LiF-induced in-situ engineering of a dense inorganic SEI for superior lithium storage in black phosphorus anode

Black phosphorus (BP) has been highly regarded as a favourable candidate for fast-charging anode applications owing to its high theoretical capacity and advantageous charge–discharge platform. However, BP faces challenges related to compromised electrochemical performance resulting from an unstable solid-electrolyte interface (SEI) and substantial volumetric expansion. This study proposes the engineering of an inorganic-dense SEI on the surface of BP-C through the strategic incorporation of lithium fluoride (LiF). The presence of LiF in the system preferentially promotes LiPF6 adsorption from the electrolyte, facilitating the in-situ formation of a lithium-enriched inorganic SEI film on the BP-C particulate surfaces. This strategic formation effectively mitigates subsequent electrolytic decomposition, accommodates volumetric expansion, and substantially improves the rate capability and cycling stability of the system. Consequently, the BP-LiF-C electrode demonstrates high initial coulombic efficiency of 86.8 % and maintains a steady capacity of 926.1 mAh g−1 over 700 cycles at 2000 mA g−1. Moreover, when paired with a LiFePO4 cathode, the full cell exhibits long cycling stability, retaining 98.6 % of its capacity after 500 cycles at 2000 mA g−1, and performs at high rate. Therefore, utilising LiF to modulate the interfacial architecture of BP-based electrode composites provide notable guidance to enhance energy storage systems.

A Synergistic Zincophilic and Hydrophobic Supramolecule Shielding Layer for Actualizing Long‐Term Zinc‐Ion Batteries

AbstractThe zinc metal anodes are liable to experience detrimental dendrite growth and side reactions, thereby limiting the lifespan of aqueous Zn‐ion batteries. Here, a readily available supramolecule, dimethoxypillar[5]arene (DP[5]), is utilized as a shielding layer to stabilize the Zn anode by exploiting its zincophilicity derived from the ─OCH3 functional groups and its hydrophobicity from the hydrophobic backbone. The DP[5] shielding layer regulates the solvation sheath of Zn2+ and facilitates uniform zinc deposition. Swelling and dendrite formation are obviously suppressed in both the symmetric and full cells. The DP[5]‐Zn symmetrical cell cycles stably for 5500 h, and achieves a coulombic efficiency of 99.76% in a DP[5]‐Zn||Cu half‐cell after 2200 cycles. The DP[5]‐Zn||V2O5 full cell maintains 92.03% of initial capacity after 6000 cycles. Given the cost‐effective fabrication and environmental friendliness of DP[5] films, this material may pave the way for practical applications of zinc anodes.

Construction of Ternary Zn0.5Cu0.5Co2O4 Spinel Structure on Nickel Foam: A Comprehensive Theoretical and Experimental Study from Single to Ternary Metal Oxides for High-Energy-Density Asymmetric Supercapacitor Application.

Developing nanostructured multi-transition metal-based spinel architectures represents a strategic approach for boosting the energy density of supercapacitors while preserving high power density. Here, the influence of incorporating Zn and Cu into Co3O4 spinel systems on supercapacitor performance is investigated by synthesizing single (ZnO, CuO, Co3O4), binary (ZnCo2O4, CuCo2O4), and ternary (Zn0.5Cu0.5Co2O4) oxides on nickel foam substrates. Theoretical and experimental analyses highlight that the flower-like structures of Zn0.5Cu0.5Co2O4, comprising nanowires and nanoribbons, effectively reduced transport barriers and enhanced ion adsorption, thereby improving electron/ion reaction kinetics. Oxygen vacancies induced defect states in Zn0.5Cu0.5Co2O4, shifting the d- and p-band center values closer to the Fermi level and enhancing electrochemical performance. The Zn0.5Cu0.5Co2O4 exhibits a specific capacity of 271 mA h g-1 (1776 F g-1) at 1 A g-1 with 97% capacity retention after 5000 charge/discharge cycles. In a Zn0.5Cu0.5Co2O4//activated carbon configuration, the device demonstrates superior energy and power densities of 122.2 Wh kg-1 and 800 W kg-1, respectively, maintaining 91% capacitance after 10000 cycles at 30 A g-1 with high coulombic efficiency. This study presents an effective strategy to enhance ion/charge transfer and adsorption in multi-transition metal spinel architectures, advancing the development of supercapacitor electrodes.

Operando Reconstruction of CuO/SnO2 Nanosheets Promotes the Syngas Production from the Electrochemical CO2 Reduction Reaction.

Electrochemically reducing CO2 (CO2RR) to high-value chemical products is recognized as a promising route to simultaneously reduce the consumption of fossil fuels and carbon emission. The fabrication of syngas with an appropriate H2/CO ratio by CO2RR has been widely studied, but the dynamic evolution of the catalyst is still ambiguous. Herein, the reconstruction of CuO/SnO2 nanosheets (NSs) with a heterojunction structure in the CO2RR process was reported by an in situ X-ray diffractometer technique. The products of the CO2RR on the optimized CuO/SnO2 NSs are CO and H2, achieving a nearly 100% total Faraday efficiency. Moreover, the resulting syngas is maintained at a constant 2:1 ratio of H2/CO over a wide potential of -0.8 to -1.2 V versus the reversible hydrogen electrode. Importantly, the detailed characterizations show that Cu2+ is reduced to Cu during the CO2RR process, while the valence state of Sn remains stable. This study presents strong experimental support for the dynamic evolution process of electrocatalysts in other energy conversion fields.