Coulombic Efficiency Research Articles

Enhancing Hydrogen Evolution Reaction through the Improved Mass Transfer and Charge Transfer by Bimetal Nodes.

The high cost of hydrogen production by water electrolysis severely challenges its commercial application. It is highly desirable to develop efficient electrocatalysts and innovative electrolytic cells. Introducing additional metal nodes to form bimetallic metal-organic framework (MOF) is a simple, feasible strategy to overcome the poor electrocatalytic performance of single-metal MOF. In this study, the hydrothermal method is used to synthesize bimetallic NixCoy-BTC. It is found that for hydrogen evolution reaction (HER), Ni0.8Co0.2-BTC merely requires a potential of -0.203 V (vs reverse hydrogen electrode, RHE) to achieve 10 mA cm-2, which is significantly lower than that of Ni-BTC (-0.341 V vs RHE). Notably, electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) analysis indicate that NixCoy-BTC has improved charge transfer and mass transfer process, compared with Ni-BTC. Electron paramagnetic resonance (EPR) confirms that Ni0.8Co0.2-BTC has more unpaired electrons than Ni-BTC. Density functional theory (DFT) calculations show that compared with Ni-BTC, NixCoy-BTC is more thermodynamically favorable for the adsorption of H+, OH-, and H2O. It demonstrates that the change of mass transfer caused by bimetallic nodes and the delicate variation of MOF surface play an important role in the electrochemical process. Moreover, a novel electrolytic cell was developed using a methanol oxidation reaction (MOR) to replace oxygen evolution reaction (OER). In this MOR-based electrolytic cell, a current density of 50 mA cm-2 can be achieved at only a cell voltage of 1.85 V, which is lower than the 2.22 V of OER-based electrolytic cell, suggesting that 16.7% electric energy can be saved. At the same time, the Faraday efficiency (FE, 98.2%) of the MOR-based cell is higher than that (94.5%) of the OER-based cell. This research offers a promising strategy for low-cost hydrogen production.

Zincophilic Sites Enriched Hydrogen‐Bonded Organic Framework as Multifunctional Regulating Interfacial Layers for Stable Zinc Metal Batteries

AbstractTo construct an efficient regulating layer for Zn anodes that can simultaneously address the issues of dendritic growth and side reactions is highly demanded for stable zinc metal batteries (ZMBs). Herein, we fabricate a hydrogen‐bonded organic framework (HOF) enriched with zincophilic sites as a multifunctional layer to regulate Zn anodes with controlled spatial ion flux and stable interfacial chemistry (MA‐BTA@Zn). The framework with abundant H‐bonds helps capture H2O and remove the solvated shells on [Zn(H2O)6]2+, leading to suppressed side reactions. The HOF layer also helps form electrolyte‐philic surfaces and expose Zn (002) crystal planes which benefit for rapid conduction and uniform deposition of Zn2+, and weakened sides reactions. Additionally, the electrochemically active zincophilic sites (C=O, −NH2 and triazine groups) favor the targeted guidance and penetration of Zn2+ and provide advantageous sites for uniform Zn deposition. High Young's modulus of the HOF layer further contributes to a high interfacial flexibility and stability against Zn plating‐associated stress. The MA‐BTA@Zn symmetric cells thereby obtain a substantially extended battery life over 1000 h at 4 mA cm−2. The MA‐BTA@Zn||Cu half‐cell demonstrates a highly reversible Zn stripping/plating process over 1500 cycles with impressive average Coulombic efficiency (CE) of 99.5 % at 10 mA cm−2.

Membrane-Free Water Electrolysis for Hydrogen Generation with Low Cost.

Conventional water electrolysis relies on expensive membrane-electrode assemblies and sluggish oxygen evolution reaction (OER) at the anode. Here, we develop an innovative and efficient membrane-free water electrolysis system to overcome these two obstacles simultaneously. This system utilizes the thermodynamically more favorable urea oxidation reaction (UOR) to generate clean N2 over a new class of Cu-based catalyst (CuXO), fundamentally eliminating the explosion risk of H2 and O2 mixing while removing the need for membranes. Notably, this membrane-free electrolysis system exhibits the highest H2 Faradaic efficiency among reported membrane-free electrolysis work. In situ spectroscopic studies reveal that the new N2Hy intermediate-mediated UOR mechanism on the CuXO catalyst ensures its unique N2 selectivity and OER inertness. More importantly, an industrial-type membrane-free water electrolyser (MFE) based on this system successfully reduces electricity consumption to only 3.87 kWh Nm-3, significantly lower than the 5.17 kWh Nm-3 of commercial alkaline water electrolyzers (AWE). Comprehensive techno-economic analysis (TEA) suggests that the membrane-free design and reduced electricity input of the MFE plants reduce the green H2 production cost to US$1.81 kg-1, which is lower than those of grey H2 while meeting the technical target (US$2.00-2.50 kg-1) set by European Commission and United States Department of Energy.

Membrane‐Free Water Electrolysis for Hydrogen Generation with Low Cost

Conventional water electrolysis relies on expensive membrane‐electrode assemblies and sluggish oxygen evolution reaction (OER) at the anode. Here, we develop an innovative and efficient membrane‐free water electrolysis system to overcome these two obstacles simultaneously. This system utilizes the thermodynamically more favorable urea oxidation reaction (UOR) to generate clean N2 over a new class of Cu‐based catalyst (CuXO), fundamentally eliminating the explosion risk of H2 and O2 mixing while removing the need for membranes. Notably, this membrane‐free electrolysis system exhibits the highest H2 Faradaic efficiency among reported membrane‐free electrolysis work. In situ spectroscopic studies reveal that the new N2Hy intermediate‐mediated UOR mechanism on the CuXO catalyst ensures its unique N2 selectivity and OER inertness. More importantly, an industrial‐type membrane‐free water electrolyser (MFE) based on this system successfully reduces electricity consumption to only 3.87 kWh Nm−3, significantly lower than the 5.17 kWh Nm−3 of commercial alkaline water electrolyzers (AWE). Comprehensive techno‐economic analysis (TEA) suggests that the membrane‐free design and reduced electricity input of the MFE plants reduce the green H2 production cost to US$1.81 kg−1, which is lower than those of grey H2 while meeting the technical target (US$2.00–2.50 kg−1) set by European Commission and United States Department of Energy.

Integrated “Two‐in‐One” Strategy for High‐Rate Electrocatalytic CO2 Reduction to Formate

AbstractThe electrochemical CO2 reduction reaction (ECR) is a promising pathway to producing valuable chemicals and fuels. Despite extensive studies reported, improving CO2 adsorption for local CO2 enrichment or water dissociation to generate sufficient H* is still not enough to achieve industrial‐relevant current densities. Herein, we report a “two‐in‐one” catalyst, defective Bi nanosheets modified by CrOx (Bi−CrOx), to simultaneously promote CO2 adsorption and water dissociation, thereby enhancing the activity and selectivity of ECR to formate. The Bi−CrOx exhibits an excellent Faradaic efficiency (≈100 %) in a wide potential range from −0.4 to −0.9 V. In addition, it achieves a remarkable formate partial current density of 687 mA cm−2 at a moderate potential of −0.9 V without iR compensation, the highest value at −0.9 V reported so far. Control experiments and theoretical simulations revealed that the defective Bi facilitates CO2 adsorption/activation while the CrOx accounts for enhancing the protonation process via accelerating H2O dissociation. This work presents a pathway to boosting formate production through tuning CO2 and H2O species at the same time.

Highly Efficient and Selective Electrocatalytic Semihydrogenation of Acetylene to Ethylene via Continuous Proton Feeding and Accelerated Transfer on Cu NP/FeNC Composite

AbstractElectrocatalytic hydrogenation of acetylene to ethylene in aqueous electrolytes under ambient conditions faces efficiency and selectivity limitation due to the competitive formation of 1,3‐butadiene and hydrogen. In this study, the development of a copper nanoparticle/FeNC composite catalyst is reported through a simple mechanical grinding approach that demonstrates remarkable performance, achieving a highest ethylene Faradaic efficiency of 97.7% at 180 mA cm−2 and selectivity of 92.6% at 200 mA cm−2. Experimental investigations reveal that Cu atoms serve as the active sites, and the integration of FeNC improves the specific surface area through its 2D nanosheet morphology. Further analysis utilizing in situ Raman measurements coupled with theoretical calculations confirms that FeNC accelerates water dissociation to provide abundant protons and improving their transfer, thereby suppressing 1,3‐butadiene formation and elevating acetylene selectivity. Notably, the integration of FeNC also transforms the desorption of *C2H4 into an exothermic process, further facilitating ethylene production. Overall, this study introduces a simple and innovative preparation approach of composite catalysts for selective ethylene synthesis, expanding the application scope of Cu‐based FeNC materials in various electrocatalytic hydrogenation reactions.

Expanded Graphite as a Superior Anion Host Carrying High Output Voltage (4.62 V) and High Energy Density for Lithium Dual-Ion Batteries

The demand for safer, sustainable, and economical energy storage devices has motivated the development of lithium dual-ion batteries (Li_DIBs) for large-scale storage applications. For the Li_DIBs, expanded graphite (EG) cathodes are valuable as anion intercalation host frameworks to fabricate safer and more cost-effective devices. In this study, three different carbon cathode materials, including microwave-treated expanded graphite (MW-EG), ball-milled expanded graphite (BM-EG), and high-temperature-carbonized carbon nanoflakes (CNFs), were developed by different synthesis methods. Li_DIBs were configured by employing 4 M of LiPF6 in a dimethyl carbonate electrolyte and MW-EG/BM-EG/CNF as an anion host cathode. After 600 cycles, a Li-MW-EG Li_DIB exhibited a reversible capacity of 66.1 mAh/g with a high Coulombic efficiency of 96.2% at a current rate of 0.05 A/g and an outstanding average energy density of 298.97 Wh/kg (with an output voltage of 4.62 V). The remarkable electrochemical results are associated with (i) moderate structural defects with a very low ID/IG ratio (0.848), (ii) degree of graphitization, which improves the mechanical stability and conductivity, and (iii) large pore volume and pore diameter, easy facilitating the accumulation of PF6− ions. The energy density characteristics demonstrate the feasibility of utilizing MW-EG as a promising cathode for energy-related Li_DIB applications.

Mechanistic Understanding of Long Duration Fast Charge Aqueous Zinc Batteries Using Physically Adsorbed Oligomers as Interphases.

Polymers have been used as additives in the liquid electrolytes typically used for secondary batteries that utilize metals as anode. Such additives are conventionally argued to improve long-term anode performance by suppressing morphological and hydrodynamic instabilities thought to be responsible for out-of-plane and dendritic metal deposition during battery charging. More recent studies have reported that the polymer additives provide even more fundamental mechanisms for stabilizing metal electrodeposition through their ability to regulate metal electrodeposit crystallography and, thereby, morphology. Few studies explore how polymers carried in a liquid electrolyte achieve these functions, and fewer still provide rules for choosing among the various polymer types, the additive polymer molecular weight (Mw), and concentration in the electrolyte. Here, we investigate how these generally easy-to-control variables influence electrochemical interphase formation inside battery cells and their impact on the morphology and reversibility of Zn electrodes in aqueous electrolytes. We focus on aqueous Zn-iodine electrochemical cells containing linear polyethylene glycol (PEG) chains as additives and find that in electrolytes where the polymer concentration is maintained in the dilute solution regime there is an optimum polymer molecular weight (Mw ≈ 1000 Da), above which beneficial effects of polymers on Zn electrode reversibility and Zn-I2 battery lifetime are progressively lost. By means of optical ellipsometry and theoretical calculations, we show that the optimal Mw is associated with saturation of the thickness of a physiosorbed PEG coating on the Zn metal electrode. Electron microscopy and X-ray photoelectron spectroscopy analysis of Zn electrodeposits formed in such electrolytes reveal that the physiosorbed polymer coating has two primary effects─it regulates the deposit morphology and suppresses parasitic reactions between the electrode and electrolyte components. The parasitic reactions produce species like ZnO, which are known to passivate the Zn electrode and promote nonuniform deposition. Galvanostatic cycling measurements in aqueous Zn-I2 cells containing the PEG additives at the optimal Mw show that the cells maintain very high Coulombic efficiencies (≥99%) at current densities as high as 50 mA/cm2─close to the maximum values permissible across the Celgard separator membranes used in our studies.

Multidentate Chelating Ligands Enable High-Performance Zinc-Bromine Flow Batteries.

Zinc bromine flow battery (ZBFB) is a promising battery technology for stationary energy storage. However, challenges specific to zinc anodes must be resolved, including zinc dendritic growth, hydrogen evolution reaction, and the occurrence of "dead zinc". Traditional additives suppress side reactions and zinc dendrite formation by altering the solvation structure of Zn2+ and adsorbing onto the zinc surface through only a limited number of zincophilic sites, resulting in weak adsorption on zinc metal and potential inability to simultaneously optimize the solvation structure of zinc ions. Obviously, increasing the number of potential zincophilic sites in the additive can significantly enhance the interaction with zinc. Herein, we propose a strong chelate, ethylenediamine tetramethylene phosphonic acid (EDTMPA) as the additive, which boasts six potent zincophilic sites, not only promotes the formation of the water-deficient inner Helmholtz plane but also plays a crucial role in restructuring the solvation environment of Zn2+. As a result, the zinc symmetric flow battery with EDTMPA exhibited exceptional coulombic efficiency of 99.4% over 800 cycles, surpassing the previous studies by a significant margin. Furthermore, the assembled ZBFB has showcased a dendrite-free and enduring cycling over 400 cycles at 80 mA cm-2.

Multidentate Chelating Ligands Enable High‐Performance Zinc‐Bromine Flow Batteries

Zinc bromine flow battery (ZBFB) is a promising battery technology for stationary energy storage. However, challenges specific to zinc anodes must be resolved, including zinc dendritic growth, hydrogen evolution reaction, and the occurrence of "dead zinc". Traditional additives suppress side reactions and zinc dendrite formation by altering the solvation structure of Zn2+ and adsorbing onto the zinc surface through only a limited number of zincophilic sites, resulting in weak adsorption on zinc metal and potential inability to simultaneously optimize the solvation structure of zinc ions. Obviously, increasing the number of potential zincophilic sites in the additive can significantly enhance the interaction with zinc. Herein, we propose a strong chelate, ethylenediamine tetramethylene phosphonic acid (EDTMPA) as the additive, which boasts six potent zincophilic sites, not only promotes the formation of the water‐deficient inner Helmholtz plane but also plays a crucial role in restructuring the solvation environment of Zn2+. As a result, the zinc symmetric flow battery with EDTMPA exhibited exceptional coulombic efficiency of 99.4% over 800 cycles, surpassing the previous studies by a significant margin. Furthermore, the assembled ZBFB has showcased a dendrite‐free and enduring cycling over 400 cycles at 80 mA cm−2.

Resource-efficient electrodes with metallized woven-glass-grid current collectors for lithium-ion batteries.

A novel class of resource-efficient, woven-glass-grid current collectors (CCs) for Li-ion batteries is introduced. These CCs are based on ultra-light multifilament glass threads, woven to a grid and surrounded with a thin metal layer (equivalent to a 1 µm-thick metal foil) in a roll-to-roll physical vapor deposition process. This saves > 90% of the required Cu and Al metals and reduces the mass of the CCs by > 80%. At the same time, the gravimetric capacity of anodes with graphite and cathodes with LiCoO2 active material increases by 48% and 14%, respectively, while full cells are characterized by an increase of 26%. Thus, the specific energy can be improved by 25%. A complete anode and cathode fabrication process from preparing the CCs and electrodes to cells is described and demonstrated in coin cell format. Coin cells with woven-glass-grid CCs achieved 300 cycles with a capacity retention of 93%, a Coulombic efficiency of > 99.9%, and a higher rate capability until a C-rate of 3C. This technology opens up new possibilities for designing ultralight CCs with dedicated surface properties for Li and beyond Li batteries.

MOF-Derived Nitrogen-Rich Hollow Nanocages as a Sulfur Carrier for High-Voltage Aluminum Sulfur Batteries.

Aluminum-sulfur batteries (ASBs) are emerging as promising energy storage systems due to their safety, low cost, and high theoretical capacity. However, it remains a challenge to overcome voltage hysteresis and short cycle life in the sulfur/Al2S3 conversion reaction, which hinders the development of ASBs. Here, we studied a high-voltage ASB system based on sulfur oxidation in an AlCl3/urea electrolyte. Nitrogen-doped hollow nanocages (HNCs) synthesized from MOF precursors were rationally designed as sulfur/carbon composite electrodes (S@HNC), and the impact of the nitrogen species on the electrochemical performance of sulfur electrodes was systematically investigated. The S@HNC-900 achieved efficient conversion at 1.9 V, delivering a stable capacity of 197.3 mA h g-1 and a Coulombic efficiency of 93.28% after 100 cycles. Furthermore, the S@HNC-900 electrode exhibited exceptional rate capacity and 800th long-term cycling stability, retaining a capacity of 87.1 mA h g-1 at 500 mA g-1. Ex situ XPS and XRD characterizations elucidated the redox mechanism, revealing a four-electron transfer process (S/AlSCl7) at the S@HNC-900 electrode. Density functional theory calculations demonstrated that pyridinic nitrogen-enriched HNC-900 significantly enhanced the sulfur conversion reaction and facilitated the adsorption of sulfur intermediates (SCl3+) on the carbon interface. This work provides critical insights into the high-voltage sulfur redox mechanism and establishes a foundation for the rational design of carbon-based electrocatalysts for the enhancement of ASB performance.

Screening of Cation Exchange Membranes for an Anthraquinone‐Ferrocyanide Flow Battery

AbstractThe disodium salt of 9,10‐anthraquinone‐2,7‐disulphonic acid (2,7‐AQDS) is an interesting platform for developing anthraquinone derivative negolytes for aqueous organic flow batteries. Recently, ammonium sulphate supporting electrolytes have been considered for improved stability and solubility. This work advances the 2,7‐AQDS/ferrocyanide flow battery with an ammonium sulphate supporting electrolyte (pH 5) by studying the suitability of six commercially available cation exchange membranes: E‐620, NR‐212, FS‐930, F‐1075‐PK, F‐1850 and N‐115. Cell cycling under galvanostatic regime plus potential hold was performed to determine coulombic efficiency, energy efficiency and accessible capacity for each membrane as well as capacity fade rate for three selected membranes under extended operation. Cell cycling under galvanostatic control only was carried out to observe transient membrane behavior alongside accessible capacity and apparent capacity fade rate. It was found that the capacity set by the limiting negolyte is consistent with 1.5 electrons per 2,7‐AQDS molecule and that energy efficiency shows a simple direct relationship to membrane thickness, with one exception. Meanwhile, four membranes displayed similar apparent capacity fade rates at this laboratory scale irrespective of their thickness, with capacity loss explained in terms of crossover. The best overall performance was attained by the thinnest membranes, E‐620 and NR‐212.

Biocatalyst for carbon veil anode in microbial fuel cells: The effect of precursor and catalyst loading on overall performance

Biocatalysts in anodes have been crucial in improving microbial fuel cell (MFC) performance. Biocatalysts derived from biomass such as coconut wood sawdust (SD-B) and pepper processing residue (PS-B), were used to improve the electrocatalytic properties of Carbon Veil (CV) electrodes. The amorphous graphitic carbon biocatalyst with a mesoporous structure was found to have a surface area of 889.31 m2/g for SD-B and 763.56 m2/g for PS-B. Surface functional groups such as -OH which imparts hydrophilicity and -C=O and COOH which promotes bacterial compatibility have been revealed to be present in both catalysts. Catalyst loading played a major role and at an optimal loading of 2 mg/cm2, the electrodes exhibited maximum electrocatalytic activity in the case of both biocatalysts. The voltammetric capacitances of SD-B and PS-B modified electrodes were 191.6 mF/cm2 and 106.6 mF/cm2 demonstrating their pseudocapacitive behaviour too. The performance of MFC with SD-B revealed a maximum power density of 10.1 W/m3 (Open Circuit Voltage (OCV) of 850 mV), followed by PS-B at 6.89 W/m3 (OCV of 825 mV) whereas the plain CV was at 0.168 W/m3 (OCV of 760 mV). Anode polarization studies indicated reduced slopes for biocatalyst-modified anodes, signifying improved electrode kinetics, particularly notable in the SD-B modified MFC where the cathode became the limiting electrode. Coulombic efficiencies of the biocatalyst-modified MFCs increased to 54.50%, (SD-B 2 mg/cm2) and 37.78% (PS-B 2 mg/cm2) respectively from 12.74% as noticed in the case of unmodified MFC. This study emphasizes the potential of biocatalysts as a simple and low-cost means of enhancing the anode properties – porosity, conductivity, hydrophilicity, and biocompatibility.

Encapsulation Engineering of Sulfur into Magnesium Oxide for High Energy Density Li-S Batteries.

This study addresses the persistent challenge of polysulfide dissolution in lithium-sulfur (Li-S) batteries by introducing magnesium oxide (MgO) nanoparticles as a novel additive. MgO was integrated with sulfur using a scalable process involving solid-state melt diffusion treatment followed by planetary ball milling. XRD measurements confirmed that sulfur (S8) retains its orthorhombic crystalline structure (space group Fddd) following the MgO incorporation, with minimal peak shifts indicating slight lattice distortion, while the increased peak intensity suggests enhanced crystallinity due to MgO acting as a nucleation site. Additionally, Raman spectroscopy demonstrated sulfur's characteristic vibrational modes consistent with group theory (point group D2h) and highlighted multiwalled carbon nanotube (MWCNT's) D, G, and 2D bands, with a low ID/IG ratio (0.47), which indicated low defects and high crystallinity in the prepared cathode. The S-MgO composite cathode exhibited superior electrochemical behavior, with an initial discharge capacity (950 mA h g-1 at 0.1 C), significantly improved compared to pristine sulfur's. The presence of MgO effectively mitigated the polysulfide shuttle effect by trapping polysulfides, leading to enhanced stability over 400 cycles and the consistent coulombic efficiency of over 99.5%. After 400 cycles, EDS and SEM analyses confirmed the structural integrity of the electrode, with only minor fractures and slight sulfur content loss. Electrochemical impedance spectroscopy further confirmed the enhanced performance.

Preparation of NiCo hydroxide by chloride corrosion for electrocatalytic upcycling of polyethylene terephthalate plastic waste

Upcycling plastic waste into value-added chemicals is an innovative strategy that addresses environmental concerns and creates economic value. As one of the polyesters that is widely used, polyethylene terephthalate (PET) plastic waste is employed as the model substrate. Here we report a chloride corrosion method to synthesize bimetallic hydroxide catalysts on nickel foam. By using a nickel–cobalt hydroxide catalyst (NiCo-OH/NF), we demonstrate an electrocatalytic oxidation strategy to transform real-world polyethylene terephthalate (PET) water bottle into potassium formate and terephthalic acid (TPA) with high Faraday efficiency of 92.1 % at 1.40 V vs. RHE. The in situ spectroscopy and theoretical calculations provide insights into the catalytic mechanism especially active sites, pivotal intermediates, and favorable pathways. This work highlights the significant potential of electrochemical conversion as a means of achieving PET upcycling.

Electrocatalytic Hydrogenation and Deuteration of Unsaturated C-N Bonds to Amines with Vacancy-rich Cu3P Nanowires as Catalysts in Aqueous Solution.

Renewable energy driven electrochemically hydrogenation of unsaturated C-N bonds with water as a hydrogen source provides an eco-friendly route for amine production. However, the potential commercial applications of this strategy were limited by the lack of relevant extended research. Here we demonstrate an efficient electrochemical hydrogenation system for the formation of amines from nitriles by a vacancy-rich copper phosphide catalyst. The catalytic system achieves a yield of 99% and a Faraday efficiency of 99% for the hydrogenation of benzonitrile. Mechanism study shows that benzonitrile is spontaneously adsorbed on the electrode surface and the electrogenerated active adsorbed hydrogen is the key reactive intermediate for hydrogenation. Theoretical calculation results show that vacancy-induced active sites chemisorb the N atom, thus accelerating C≡N bond activation for hydrogenation. Encouragingly, good yields of amines (≥99%) are obtained when benzonitrile is replaced by a series of aromatic nitriles, heterocyclic nitriles, aliphatic nitriles, and imines. These results show the general applicability of this method for the synthesis of various amines.

Constructing Ag/Cu2O Interface for Efficient Neutral CO2 Electroreduction to C2H4.

Neutral CO2 electroreduction to multi-carbons (C2+) offers a promising pathway to reduce the CO2 and energy losses originating from the carbonate formation. However, the sluggish kinetics of C-C coupling brings a significant challenge of achieving high selectivity of a single product (such as ethylene), especially at industrial-relevant current densities (>300 mA cm-2). Here, we reported an optimized Ag-Cu2O interfacial catalyst that exhibited C2+ Faradaic efficiency (FE) of 73.6 % at 650 mA cm-2 in a flow cell. Remarkably, it obtained FEC2H4 of 66.0 % with a partial current density of 429.1 mA cm-2, making it stand out among the reported Cu-based electrocatalysts. In situ Raman spectra uncovered that the Ag/Cu2O interfaces enabled a high coverage of *CO around the partially reduced Cu+/Cu0 active sites. Furthermore, theoretical calculations demonstrated the enhanced CO formation and C-C coupling at the Ag/Cu2O interface. This work reported an unprecedented neutral CO2 electroreduction to C2H4 performance and provided an in-depth comprehension of the role of the bimetallic interface.

Advances in the Application of Graphene in Lithium-ion Batteries

The search for effective energy storage options has escalated due to the rising global energy demands and environmental concerns. Lithium-ion batteries (LIBs) emerge as a key technology. However, the performance of traditional LIBs still needs to be improved. Therefore, choosing new nanomaterials for the modification of LIBs has become an effective solution. Graphene, as a nanomaterial, is an excellent candidate material for modification. This paper delves into the application of graphene in enhancing the performance of LIBs. Graphene, with its superior electrical conductivity and substantial specific surface area, offers the potential to enhance the performance of both anode and cathode materials in LIBs. This can lead to significant improvements in the overall cycle life, energy density, and power density of these batteries. This work emphasizes the application of graphene in cathode and anode materials. In cathode materials, the layered structure of graphene enables lithium-ion with high theoretical capacity. Meanwhile, graphene helps improve the electron and lithium ion mobility of anode materials. Despite the promising developments, challenges such as lithium loading capacity and coulombic efficiency still remain. The continued exploration of graphene applications is expected to drive LIBs to unprecedented performance metrics. This is in line with the global quest for sustainable and efficient energy storage technologies.

Enhanced Local CO Coverage on Cu Quantum Dots for Boosting Electrocatalytic CO2 Reduction to Ethylene

AbstractEthylene (C2H4) electrosynthesis from the electrocatalytic CO2 reduction process holds enormous potential applications in industrial production. However, the sluggish kinetics of C─C coupling often result in low yield and poor selectivity for C2H4 production. Herein, the performance of Cu catalysts of varying sizes is investigated, prepared via a cryo‐mediated liquid phase exfoliation technique, for the electrochemical CO2 reduction to C2H4. The activity and selectivity of C2H4 gradually increase as the size of the Cu catalysts decreases from tens of nanometers to a few nanometers. Impressively, the 5 nm Cu quantum dots (Cu‐5) achieve a maximum C2H4 Faradaic efficiency (FE) of 81.5% and a half‐cell cathodic energy efficiency (CEE) of 42.2% with a large partial current density of 1.1 A cm−2 at −0.93 V versus the reversible hydrogen electrode. Structural characterization and in situ spectroscopic analysis reveal that the Cu‐5 quantum dots, dominated by the (100) facet, provide an abundance of active sites that enhance CO2 adsorption and activation, promoting the formation of *CO intermediates. The accumulation of *CO intermediates on the Cu active sites facilitates the CO‐CHO coupling reaction, thus enhancing the C2H4 production rate.