Synergistic Effect of Co-Mo Pinning in Lay-Structured Oxide Cathode for Enhancing Stability toward Potassium-Ion Batteries.

Owing to the high economic efficiency and energy density potential, manganese-based layer-structured oxides have attracted great interests as cathode materials for potassium ion batteries. In order to alleviate the continuous phase transition and K+ re-embedding from Jahn-Teller distortion, the [Mn-Co-Mo]O6 octahedra are introduced into P3-K0.45MnO2 herein to optimize the local electron structure. Based on the experimental and computational results, the octahedral center metal molybdenum in [MoO6] octahedra proposes a smaller ionic radius and higher oxidation state to induce second-order JTE (pseudo-JTE) distortion in the adjacent [MnO6] octahedra. This distortion compresses the [MnO6] octahedra along the c-axis, leading to an increased interlayer spacing in the K+ layer. Meanwhile, the Mn3+/Mn4+ is balanced by [CoO6] octahedra and the K+ diffusion pathway is optimized as well. The proposed P3-K0.45Mn0.9Co0.05Mo0.05O2 cathode material shows an enhanced cycling stability and rate performance. It demonstrates a high capacity of 80.2 mAh g-1 at 100 mAh g-1 and 77.3 mAh g-1 at 500 mAh g-1. Furthermore, it showcases a 2000 cycles stability with a 59.6% capacity retention. This work presents a promising solution to the challenges faced by manganese-based layered oxide cathodes and offers a deep mechanism understanding and improved electrochemical performance.

Constructing Cyclic Hydrogen Bonding to Suppress Side Reactions and Dendrite Formation on Zinc Anodes.

The high electrochemical reactivity of H2O molecules and zinc metal results in severe side reactions and dendrite formation on zinc anodes. Here we demonstrate that these issues can be addressed by using N-hydroxymethylacetamide (NHA) as additives in 2 M ZnSO4 electrolytes. The addition of NHA molecules, acting as both a hydrogen bond donor and acceptor, enables the formation of cyclic hydrogen bonding with H2O molecules. This interaction disrupts the existing hydrogen bonding networks between H2O molecules, hindering proton transport, and containing H2O molecules within the cyclic hydrogen bonding structure to prevent deprotonation. Additionally, NHA molecules show a preference for adsorption on the (101) crystal surface of zinc metal. This preferential adsorption reduces the surface energy of the (101) plane, facilitating the homogeneous Zn deposition along the (101) direction. Thus, the NHA enables Zn||Zn symmetric cell with a cycle lifespan of 1100 hours at 5 mA cm-2 and Zn||Cu asymmetric cell with a high Coulombic efficiency over 99.5%. Moreover, the NHA-modified Zn||AC zinc ion hybrid capacitor is capable of sustaining 15000 cycles at 2 A g-1. This electrolyte additive engineering presents a promising strategy to enhance the performance and broaden the application potential of zinc metal-based energy storage devices.

Binder-Free and Carbon-Free 3D Porous Air Electrode for Li-O2 Batteries with High Efficiency, High Capacity, and Long Life.

Pt-Gd alloy polycrystalline thin film is deposited on 3D nickel foam by pulsed laser deposition method serving as a whole binder/carbon-free air electrode, showing great catalytic activity enhancement as an efficient bifunctional catalyst for the oxygen reduction and evolution reactions in lithium oxygen batteries. The porous structure can facilitate rapid O2 and electrolyte diffusion, as well as forming a continuous conductive network throughout the whole energy conversion process. It shows a favorable cycle performance in the full discharge/charge model, owing to the high catalytic activity of the Pt-Gd alloy composite and 3D porous nickel foam structure. Specially, excellent cycling performance under capacity limited mode is also demonstrated, in which the terminal discharge voltage is higher than 2.5 V and the terminal charge voltage is lower than 3.7 V after 100 cycles at a current density of 0.1 mA cm(-2) . Therefore, this electrocatalyst is a promising bifunctional electrocatalyst for lithium oxygen batteries and this depositing high-efficient electrocatalyst on porous substrate with polycrystalline thin film by pulsed laser deposition is also a promising technique in the future lithium oxygen batteries research.

Ambient Electrochemical Ammonia Synthesis: From Theoretical Guidance to Catalyst Design.

Ammonia, a vital component in the synthesis of fertilizers, plastics, and explosives, is traditionally produced via the energy-intensive and environmentally detrimental Haber-Bosch process. Given its considerable energy consumption and significant greenhouse gas emissions, there is a growing shift toward electrocatalytic ammonia synthesis as an eco-friendly alternative. However, developing efficient electrocatalysts capable of achieving high selectivity, Faraday efficiency, and yield under ambient conditions remains a significant challenge. This review delves into the decades-long research into electrocatalytic ammonia synthesis, highlighting the evolution of fundamental principles, theoretical descriptors, and reaction mechanisms. An in-depth analysis of the nitrogen reduction reaction (NRR) and nitrate reduction reaction (NitRR) is provided, with a focus on their electrocatalysts. Additionally, the theories behind electrocatalyst design for ammonia synthesis are examined, including the Gibbs free energy approach, Sabatier principle, d-band center theory, and orbital spin states. The review culminates in a comprehensive overview of the current challenges and prospective future directions in electrocatalyst development for NRR and NitRR, paving the way for more sustainable methods of ammonia production.

Polymetal-Chelated Fabrication of Bimetallic Nanophosphides as Electrocatalysts for Zinc-Air Batteries.

Bimetallic phosphides are considered as promising electrocatalysts for zinc-air batteries toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). To address the semi-conductor inherent low electronic conductivity and catalytic activity, a polymetal-chelated strategy is employed to in situ fabricate bimetallic nanophosphides within carbon matrix anchoring by chemical bonding. The employment of biomolecule polydopamine (PDA) efficiently anchors various transition metal ions due to its strong chelating capability via inherent functional groups. Furthermore, the chelation of multi-metal ion is proved to promote the formation of graphitic nitrogen. The bimetallic FexCoyP phosphides nanoparticles are intimately encapsulated in carbon matrix through in situ carbonization and phosphatization processes. When utilized in Zinc-air batteries, Fe0.20Co0.80P anchored within N, P co-doped sub-microsphere (Fe0.20Co0.80P /PNC) exhibit a maximum power density of 167 mW cm-2 and cycle life up to 270 cycles, with a round-trip voltage of 0.955 V. The mechanisms for catalytic activity passivation are ascribed to the etching of nitrogen and oxidation of phosphorus in carbon matrix, as well as the oxidation of the surface phosphide on the sub-microspheres. This study presents a promising candidate for advancing the further development of energy conversation catalysis.

CuS nanoflakes, microspheres, microflowers, and nanowires: synthesis and lithium storage properties.

CuS nanostructured materials, including nanoflakes, microspheres composed of nanoflakes, microflowers, and nanowires have been selectively synthesized by a facile hydrothermal method using CuSO4 and thiourea as precursors under different conditions. The morphology of CuS particles were affected by the following synthetic parameters: temperature, time, surfactant, pH value, solvent, and concentration of the two precursors. The synthesized CuS nanomaterials were characterized by X-ray diffraction, Brunauer-Emmett-Teller N2 adsorption, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The electrochemical tests, including constant current charge-discharge and cyclic voltammetry, show the specific capacities of the different morphologies, as well as their rate capability. The nanowire electrode has near theoretical specific capacity and the best rate capability.

Layer-Structured Multitransition-Metal Oxide Cathode Materials for Potassium-Ion Batteries with Long Cycling Lifespan and Superior Rate Capability.

Manganese (Mn)-based layer-structured transition metal oxides are considered as excellent cathode materials for potassium ion batteries (KIBs) owing to their low theoretical cost and high voltage plateau. The energy density and cycling lifetime, however, cannot simultaneously satisfy the basic requirements of the market for energy storage systems. One of the primary causes results from the complex structural transformation and transition metal migration during the ion intercalation and deintercalation process. The orbital and electronic structure of the octahedral center metal element plays an important role for maintaining the octahedral structural integrity and improving the K+ diffusivity by the introduced heterogeneous [Me-O] chemical bonding. A multitransition metal oxide, P3-type K0.5Mn0.85Co0.05Fe0.05Al0.05O2 (KMCFAO), was synthesized and employed as a cathode material for KIBs. Beneficial from the larger layer spacing for K+ to better accommodate and effectively preventing the irreversible structural transformation in the insertion/extraction process, it can reach a superior capacity retention up to 96.8% after 300 cycles at a current density of 500 mA g-1. The full cell of KMCFAO//hard carbon exhibits an encouraging promising energy density of 113.8 W h kg-1 at 100 mA g-1 and a capacity retention of 72.6% for 500 cycles.

Enhanced cycling performance of nanocrystalline Fe3O4/C as anode material for lithium-ion batteries.

Fe3O4-carbon composite was prepared by the sol-gel method. The crystal structure, morphology, and phases present in the product were investigated by X-ray diffraction and by scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy and field-emission SEM. Electrochemical characterization was performed using constant current charge-discharge testing and electrochemical impedance spectroscopy. The Fe3O4/C electrode has high initial columbic efficiency (87%) and outstanding cycling performance (775.3 mAh g(-1) after 90 cycles at a current density of 100 mA g(-1)).

One-step spray pyrolysis synthesized CuO-carbon composite combined with carboxymethyl cellulose binder as anode for lithium-ion batteries.

Copper oxide-carbon composite with hollow sphere structure has been synthesized by a one-step spray pyrolysis method and tested as anode material for lithium-ion batteries. Different analytical methods, including X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and systematic electrochemical tests were performed. The results demonstrate that the CuO-carbon composite in conjunction with carboxymethyl cellulose (CMC) binder has an excellent electrochemical performance, with a capacity of 577 mAh g(-1) up to 100 cycles. The usage of the water soluble binder, CMC, not only obviously improves the electrochemical performance, but also makes the electrode fabrication process much easier and more environmentally friendly.

New Phosphate Zn2Fe(PO4)2 Cathode Material for Nonaqueous Zinc Ion Batteries with Long Life Span.

Phosphate-based cathode materials attract much more attention and are widely used as energy storage materials based on their high economic efficiency and eco-friendly property, their stable potential plateau, and their high thermodynamic stability. A new phosphate family member, Zn2Fe(PO4)2 (ZFP), was successfully explored and synthesized by the scalable high-temperature annealing method, followed by coating a thin carbon layer to optimize the electrotonic conductivity. This obtained ZFP featuring with a tunnel structure can be utilized as a cathode material for Zn2+ ion extraction and insertion, in which Zn2+ ion diffusion behaviors primarily contribute the specific capacity. Based on the actual reversible capacity of ZFP@C of 73 mA h g-1, the application for zinc ion batteries (ZIBs) has potential due to its long life span. The electrochemical performance is primarily contributed from the high Zn2+ ion diffusion rate and low apparent activation energy. This new explored ZFP can accelerate the development of realizing ZIBs with long life span.

Highly Efficient SO2 Sensing by Light-Assisted Ag/PANI/SnO2 at Room Temperature and the Sensing Mechanism.

Sulfur dioxide (SO2) is one of the most hazardous and common environmental pollutants. However, the development of room-temperature SO2 sensors is seriously lagging behind that of other toxic gas sensors due to their poor recovery properties. In this study, a light-assisted SO2 gas sensor based on polyaniline (PANI) and Ag nanoparticle-comodified tin dioxide nanostructures (Ag/PANI/SnO2) was developed and exhibited remarkable SO2 sensitivity and excellent recovery properties. The response of the Ag/PANI/SnO2 sensor (20.1) to 50 ppm SO2 under 365 nm ultraviolet (UV) light illumination at 20 °C was almost 10 times higher than that of the pure SnO2 sensor. Significantly, the UV-assisted Ag/PANI/SnO2 sensor had a rapid response time (110 s) and recovery time (100 s) to 50 ppm SO2, but in the absence of light, the sensors exhibited poor recovery performance or were even severely and irreversibly deactivated by SO2. The UV-assisted Ag/PANI/SnO2 sensor also exhibited excellent selectivity, superior reproducibility, and satisfactory long-term stability at room temperature. The increased charge carrier density, improved charge-transfer capability, and the higher active surface of the Ag/PANI/SnO2 sensor were revealed by electrochemical measurements and endowed with high SO2 sensitivity. Moreover, the light-induced formation of hot electrons in a high-energy state in Ag/PANI/SnO2 significantly facilitated the recovery of SO2 by the gas sensor.

Metallic-State MoS2 Nanosheets with Atomic Modification for Sodium Ion Batteries with a High Rate Capability and Long Lifespan.

Exploring active materials with a high rate capability and long lifespan for sodium ion batteries attracts much more attention and plays an important role in realizing clean energy storage and conversion. The strategy of optimizing the electronic structure by atomic element substitution within MoS2 layers was employed to change the inherent physical property. The enhanced electronic conductivity from a decreased bandgap and increased surface Na+ adsorption energy can efficiently and dramatically optimize the electrochemical performance for sodium storage. Attempting to limit the large volume variation and avoid MoS2 nanosheet stacking and restacking, numerous nanosheets are in situ grown into a designed hierarchical mesopore carbon matrix. This structure can tightly capture the nanosheets to prevent them from aggregating and offer a sufficient buffer zone for alleviating severe volume changes during the discharging/charging process, contributing remarkably to the structural integrity and superior rate performance of electrodes.

Bimetallic Sulfide Sb2S3@FeS2 Hollow Nanorods as High-Performance Anode Materials for Sodium-Ion Batteries.

Constructing a heterojunction and introducing an interfacial interaction by designing ideal structures have the inherent advantages of optimizing electronic structures and macroscopic mechanical properties. An exquisite hierarchical heterogeneous structure of bimetal sulfide Sb2S3@FeS2 hollow nanorods embedded into a nitrogen-doped carbon matrix is fabricated by a concise two-step solvothermal method. The FeS2 interlayer expands in situ grow on the interface of hollow Sb2S3 nanorods within the nitrogen-doped graphene matrix, forming a delicate heterostructure. Such a well-designed architecture affords rapid Na+ diffusion and improves charge transfer at the heterointerfaces. Meanwhile, the strongly synergistic coupling interaction among the interior Sb2S3, interlayer FeS2, and external nitrogen-doped carbon matrix creates a stable nanostructure, which extremely accelerates the electronic/ion transport and effectively alleviates the volume expansion upon long cyclic performance. As a result, the composite, as an anode material for sodium-ion batteries, exhibits a superior rate capability of 537.9 mAh g-1 at 10 A g-1 and excellent cyclic stability with 85.7% capacity retention after 1000 cycles at 5 A g-1. Based on the DFT calculation, the existing constructing heterojunction in this composite can not only optimize the electronic structure to enhance the conductivity but also favor the Na2S adsorption energy to accelerate the reaction kinetics. The outstanding electrochemical performance sheds light on the strategy by the rational design of hierarchical heterogeneous nanostructures for energy storage applications.

Binder-Free 3D Integrated Ni@Ni3Pt Air Electrode for Zn-Air Batteries.

Developing an air electrode with high efficiency and stable performance is essential to improve the energy conversion efficiency and lifetime of zinc-air battery. Herein, Ni3Pt alloy is deposited on 3D nickel foam by a pulsed laser deposition method, working as a stable binder-free air electrode for rechargeable zinc-air batteries. The polycrystalline Ni3Pt alloy possesses high oxygen-conversion catalytic activity, which is highly desirable for the charge and discharge process in zinc-air battery. Meanwhile, this sample technique constructs an integrated and stable electrode structure, which not only has a 3D architecture of high conductivity and porosity but also produces a uniform Ni3Pt strongly adhering to the substrate, favoring rapid gas and electrolyte diffusion throughout the whole energy conversion process. Employed as an air electrode in zinc-air batteries, it exhibits a small charge and discharge gap of below 0.62 V at 10 mA cm-2, with long cycle life of 478 cycles under 10 min per cycle. Furthermore, benefitting from the structural advantages, a flexible device exhibits similar electrochemical performance even under the bending state. The high performance resulting from this type of integrated electrode in this work paves the way of a promising technique to fabricate air electrodes for zinc-air batteries.

Porous AgPd-Pd Composite Nanotubes as Highly Efficient Electrocatalysts for Lithium-Oxygen Batteries.

Porous AgPd-Pd composite nanotubes (NTs) are used as an efficient bifunctional catalyst for the oxygen reduction and evolution reactions in lithium-oxygen batteries. The porous NT structure can facilitate rapid O2 and electrolyte diffusion through the NTs and provide abundant catalytic sites, forming a continuous conductive network throughout the entire energy conversion process, with excellent cycling performance.

Novel germanium/polypyrrole composite for high power lithium-ion batteries.

Nano-Germanium/polypyrrole composite has been synthesized by chemical reduction method in aqueous solution. The Ge nanoparticles were directly coated on the surface of the polypyrrole. The morphology and structural properties of samples were determined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis was carried out to determine the polypyrrole content. The electrochemical properties of the samples have been investigated and their suitability as anode materials for the lithium-ion battery was examined. The discharge capacity of the Ge nanoparticles calculated in the Ge-polypyrrole composite is 1014 mAh g(-1) after 50 cycles at 0.2 C rate, which is much higher than that of pristine germanium (439 mAh g(-1)). The composite also demonstrates high specific discharge capacities at different current rates (1318, 1032, 661, and 460 mAh g(-1) at 0.5, 1.0, 2.0, and 4.0 C, respectively). The superior electrochemical performance of Ge-polypyrrole composite could be attributed to the polypyrrole core, which provides an efficient transport pathway for electrons. SEM images of the electrodes have demonstrated that polypyrrole can also act as a conductive binder and alleviate the pulverization of electrode caused by the huge volume changes of the nanosized germanium particles during Li(+) intercalation/de-intercalation.

Tin/polypyrrole composite anode using sodium carboxymethyl cellulose binder for lithium-ion batteries.

A tin nanoparticle/polypyrrole (nano-Sn/PPy) composite was prepared by chemically reducing and coating Sn nanoparticles onto the PPy surface. The composite shows a much higher surface area than the pure nano-Sn reference sample, due to the porous higher surface area of PPy and the much smaller size of Sn in the nano-Sn/PPy composite than in the pure tin nanoparticle sample. Poly(vinylidene fluoride) (PVDF) and sodium carboxymethyl cellulose (CMC) were also used as binders, and the electrochemical performance was investigated. The electrochemical results show that both the capacity retention and the rate capability are in the same order of nano-Sn/PPy-CMC > nano-Sn/PPy-PVDF > nano-Sn-CMC > nano-Sn-PVDF. Scanning electronic microscopy (SEM) and electrochemical impedance spectroscopy (EIS) results show that CMC can prevent the formation of cracks in electrodes caused by the big volume changes during the charge-discharge process, and the PPy in the composite can provide a conducting matrix and alleviate the agglomeration of Sn nanoparticles. The present results indicate that the nano-Sn/PPy composite could be suitable for the next generation of anode materials with relatively good capacity retention and rate capability.