Surface plasmon mediates the visible light-responsive lithium-oxygen battery with Au nanoparticles on defective carbon nitride

Mechanistic understanding of CO2 reduction and evolution reactions in Li-CO2 batteries

Rechargeable Li-CO2 batteries have attracted extensive attention owing to their high theoretical energy density (1876 W h Kg-1). However, their practical application is hindered by large polarization, low coulombic efficiency, and cathode degradation. The electrochemical performance of Li-CO2 batteries is significantly affected by the thermodynamic stability and reaction kinetics of discharge products. Although advances have been achieved in cathode design and electrolyte optimization over the past decade, the reaction mechanism of the CO2 cathode has not yet been clear. In this review, various reaction mechanisms of CO2 reduction and evolution at the cathode interface are discussed, including different reaction routes under mixed O2/CO2 and pure CO2 environments. Furthermore, the regulating strategies of different discharge products, including Li2CO3, Li2C2O6, and Li2C2O4, are summarized to decrease the polarization and improve the cycling performance of Li-CO2 batteries. Finally, the challenges and perspectives are discussed from three aspects: reaction mechanisms, cathode catalysts, and electrolyte engineering, offering insights for the development of Li-CO2 batteries in the future.

Photo-Assisted Li-N2 Batteries with Enhanced Nitrogen Fixation and Energy Conversion

Li-N2 batteries have received widespread attention for their potential to integrate N2 fixation, energy storage, and conversion. However, because of the low activity and poor stability of cathode catalysts, the electrochemical performance of Li-N2 batteries is suboptimal, and their electrochemical reversibility has rarely been proven. In this study, a novel bifunctional photo-assisted Li-N2 battery system was established by employing a plasmonic Au nanoparticles (NPs)-modified defective carbon nitride (Au-Nv -C3 N4 ) photocathode. The Au-Nv -C3 N4 exhibits strong light-harvesting, N2 adsorption, and N2 activation abilities, and the photogenerated electrons and hot electrons are remarkably beneficial for accelerating the discharge and charge reaction kinetics. These advantages enable the photo-assisted Li-N2 battery to achieve a low overpotential of 1.32 V, which is the lowest overpotential reported to date, as well as superior rate capability and prolonged cycle stability (≈500 h). Remarkably, a combination of theoretical and experimental results demonstrates the high reversibility of the photo-assisted Li-N2 battery. The proposed novel strategy for developing efficient cathode catalysts and fabricating photo-assisted battery systems breaks through the overpotential bottleneck of Li-N2 batteries, providing important insights into the mechanism underlying N2 fixation and storage.

Enhanced molecular oxygen activation via K/O interfacial modification for boosted electrocatalytic degradation over a broad pH range

Molecular oxygen activation plays an important role in the electrocatalytic degradation of recalcitrant pollutants. And the key lies in the tailoring of electronic structures over catalysts. Herein, carbon nitride with K/O interfacial modification (KOCN) was designed and fabricated for efficient molecular oxygen activation. Theoretical screening results revealed the possible substitution of peripheral N atoms by O atoms and the location of K atoms in the six-fold cavities of g-C3N4 framework. Spectroscopic and experimental results reveal that the existence of K/O promotes charge redistribution over as-prepared catalysts, leading to optimized electronic structures. Therefore, optimized oxygen adsorption was realized over 8 % KOCN, which was further converted into superoxide and singlet oxygen effectively. The rate constant of 8 % KOCN (1.8 × 10-2 min-1) reached 2.2 folds of pristine g-C3N4 (8.1 × 10-3 min-1) counterpart during tetracycline degradation. Moreover, the high electron mobility and excellent structural stability endow the catalyst with remarkable catalytic performance in a broad pH range of 3-11.

Progress of charge carrier dynamics and regulation strategies in 2D CxNy-based heterojunctions

Two-dimensional carbon nitrides (CxNy) have gained significant attention in various fields including hydrogen energy development, environmental remediation, optoelectronic devices, and energy storage owing to their extensive surface area, abundant raw materials, high chemical stability, and distinctive physical and chemical characteristics. One effective approach to address the challenges of limited visible light utilization and elevated carrier recombination rates is to establish heterojunctions for CxNy-based single materials (e.g. C2N3, g-C3N4, C3N4, C4N3, C2N, and C3N). The carrier generation, migration, and recombination of heterojunctions with different band alignments have been analyzed starting from the application of CxNy with metal oxides, transition metal sulfides (selenides), conductive carbon, and Cx'Ny' heterojunctions. Additionally, we have explored diverse strategies to enhance heterojunction performance from the perspective of carrier dynamics. In conclusion, we present some overarching observations and insights into the challenges and opportunities associated with the development of advanced CxNy-based heterojunctions.

Facile synthesis of multi-layer Co(OH)2/CeO2-g-C3N4 ternary synergistic heterostructure for efficient photocatalytic oxidation of NO under visible light

In this work, we report a one-step synthesis of ternary Z-scheme Co(OH)2/CeO2-g-C3N4 (CoCe-CN) heterostructure via hydrothermal method. Owing to the modification of Co(OH)2 and CeO2, the existence of Co(OH)2 as an electron acceptor-donor center between CeO2 and g-C3N4 accelerates the electron transfer and provides extra OH- reaction pathway for photocatalytic oxidation of NO. As a result, 50CoCe-CN (Co and Ce accounting for 25% mass ratio separately) achieved a 53.5% conversion efficiency of NO at 600 ppb concentration, which is 1.82 times that of g-C3N4 under visible light. The results of the DFT analysis and element distribution of cobalt and ceria provide convincing evidence supporting the existence of a novel multi-layer structure in the CoCe-CN photocatalyst. This structure involves the loading of CeO2 and Co(OH)2 on the g-C3N4 surface, and Co(OH)2 as a co-catalyst introduced between CeO2 and g-C3N4 realizes the synergy between CeO2 and Co(OH)2 which further improve the photocatalytic properties. The higher photocatalytic efficiencies observed in the CoCe-CN photocatalysts compared to those containing only cobalt (Co-CN) or ceria (Ce-CN) provide further evidence of the synergistic effect of these two elements. This work demonstrates a more efficient and effective ternary photocatalytic system, with greater practical potential for photocatalytic oxidation of NO.

Recent Progress in Hot Spot Regulated Strategies for Catalysts Applied in Li-CO2 Batteries

As a high energy density power system, lithium-carbon dioxide (Li-CO2 ) batteries play an important role in addressing the fossil fuel crisis issues and alleviating the greenhouse effect. However, the sluggish transformation kinetic of CO2 and the difficult decomposition of discharge products impede the achievement of large capacity, small overpotential, and long life span of the batteries, which require exploring efficient catalysts to resolve these problems. In this review, the main focus is on the hot spot regulation strategies of the catalysts, which include the modulation of the active sites, the designing of microstructure, and the construction of composition. The recent progress of promising catalysis with hot spot regulated strategies is systematically addressed. Critical challenges are also presented and perspectives to provide useful guidance for the rational design of highly efficient catalysts for practical advanced Li-CO2 batteries are proposed.

Multifunctional carbon nitride nanoarchitectures for catalysis

Catalysis is at the heart of modern-day chemical and pharmaceutical industries, and there is an urgent demand to develop metal-free, high surface area, and efficient catalysts in a scalable, reproducible and economic manner. Amongst the ever-expanding two-dimensional materials family, carbon nitride (CN) has emerged as the most researched material for catalytic applications due to its unique molecular structure with tunable visible range band gap, surface defects, basic sites, and nitrogen functionalities. These properties also endow it with anchoring capability with a large number of catalytically active sites and provide opportunities for doping, hybridization, sensitization, etc. To make considerable progress in the use of CN as a highly effective catalyst for various applications, it is critical to have an in-depth understanding of its synthesis, structure and surface sites. The present review provides an overview of the recent advances in synthetic approaches of CN, its physicochemical properties, and band gap engineering, with a focus on its exclusive usage in a variety of catalytic reactions, including hydrogen evolution reactions, overall water splitting, water oxidation, CO2 reduction, nitrogen reduction reactions, pollutant degradation, and organocatalysis. While the structural design and band gap engineering of catalysts are elaborated, the surface chemistry is dealt with in detail to demonstrate efficient catalytic performances. Burning challenges in catalytic design and future outlook are elucidated.

Tailoring the p-Band Center of NS Pair for Accelerating High-Performance Lithium-Oxygen Battery

The local coordination environment of catalytical moieties directly determines the performance of electrochemical energy storage and conversion devices, such as Li-O₂ batteries (LOBs) cathode. However, understanding how the coordinative structure affects the performance, especially for non-metal system, is still insufficient. Herein, a strategy that introduces S-anion to tailor the electronic structure of nitrogen-carbon catalyst (SNC) is proposed to improve the LOBs performance. This study unveils that the introduced S-anion effectively manipulates the p-band center of pyridinic-N moiety, substantially reducing the battery overpotential by accelerating the generation and decomposition of intermediate products Li_1-3 O₄ . The lower adsorption energy of discharging product Li₂ O₂ on NS pair accounts for the long-term cyclic stability by exposing the high active area under operation condition. This work demonstrates an encouraging strategy to enhance LOBs performance by modulating the p-band center on non-metal active sites.

Metal-Organic Framework-Based Mixed Conductors Achieve Highly Stable Photo-assisted Solid-State Lithium-Oxygen Batteries

The demand for high-energy sustainable rechargeable batteries has motivated the development of lithium-oxygen (Li-O₂) batteries. However, the inherent safety issues of liquid electrolytes and the sluggish reaction kinetics of existing cathodes remain fundamental challenges. Herein, we demonstrate a promising photo-assisted solid-state Li-O₂ battery based on metal-organic framework-derived mixed ionic/electronic conductors, which simultaneously serve as the solid-state electrolytes (SSEs) and the cathode. The mixed conductors could effectively harvest ultraviolet-visible light to generate numerous photoelectrons and holes, which is favorable to participate in the electrochemical reaction, contributing to greatly improved reaction kinetics. According to the study on conduction behavior, we discover that the mixed conductors as SSEs possess outstanding Li⁺ conductivity (1.52 × 10^-4 S cm^-1 at 25 °C) and superior chemical/electrochemical stability (especially toward H₂O, O₂^-, etc.). Application of mixed ionic electronic conductors in photo-assisted solid-state Li-O₂ batteries further reveals that a high energy efficiency (94.2%) and a long life (320 cycles) can be achieved with a simultaneous design of SSEs and cathodes. The achievements present the widespread universality in accelerating the development of safe and high-performance solid-state batteries.

Defect engineering of two-dimensional materials for advanced energy conversion and storage

In the global trend towards carbon neutrality, sustainable energy conversion and storage technologies are of vital significance to tackle the energy crisis and climate change. However, traditional electrode materials gradually reach their property limits. Two-dimensional (2D) materials featuring large aspect ratios and tunable surface properties exhibit tremendous potential for improving the performance of energy conversion and storage devices. To rationally control the physical and chemical properties for specific applications, defect engineering of 2D materials has been investigated extensively, and is becoming a versatile strategy to promote the electrode reaction kinetics. Simultaneously, exploring the in-depth mechanisms underlying defect action in electrode reactions is crucial to provide profound insight into structure tailoring and property optimization. In this review, we highlight the cutting-edge advances in defect engineering in 2D materials as well as their considerable effects in energy-related applications. Moreover, the confronting challenges and promising directions are discussed for the development of advanced energy conversion and storage systems.

CO2 Capture Membrane for Long-Cycle Lithium-Air Battery

Lithium-air batteries (LABs) have attracted extensive attention due to their ultra-high energy density. At present, most LABs are operated in pure oxygen (O₂) since carbon dioxide (CO₂) under ambient air will participate in the battery reaction and generate an irreversible by-product of lithium carbonate (Li₂CO₃), which will seriously affect the performance of the battery. Here, to solve this problem, we propose to prepare a CO₂ capture membrane (CCM) by loading activated carbon encapsulated with lithium hydroxide (LiOH@AC) onto activated carbon fiber felt (ACFF). The effect of the LiOH@AC loading amount on ACFF has been carefully investigated, and CCM has an ultra-high CO₂ adsorption performance (137 cm³ g^-1) and excellent O₂ transmission performance by loading 80 wt% LiOH@AC onto ACFF. The optimized CCM is further applied as a paster on the outside of the LAB. As a result, the specific capacity performance of LAB displays a sharp increase from 27,948 to 36,252 mAh g^-1, and the cycle time is extended from 220 h to 310 h operating in a 4% CO₂ concentration environment. The concept of carbon capture paster opens a simple and direct way for LABs operating in the atmosphere.

Bifunctional Photoassisted Li-O2 Battery with Ultrahigh Rate-Cycling Performance Based on Siloxene Size Regulation

Directly integrating the bifunctional photoelectrode into Li-O2 batteries has been considered an effective way to reduce the overpotential and promote electric energy saving. However, more regular investigations on various bifunctional photocatalysts have still been desired for high-performance photoassisted Li-O2 batteries. Herein, a systematic exploration of various-sized siloxene photocatalysts affected by Li-O2 batteries has been introduced. Compared with the utilization of larger-sized siloxene nanosheets (SNSs), the photoassisted Li-O2 battery with a siloxene quantum dot (SQD) photoelectrode delivers a superior round-trip efficiency of 230% based on the highest discharge potential up to 3.72 V and lowest charge potential of 1.60 V and enables the maintenance of a long-term cycling life with only 13% efficiency attenuation after 200 cycles at 0.075 mA/cm2. Furthermore, this system exhibits a record-high rate-cycling performance (162% round-trip efficiency, even at 3 mA/cm2) and a high discharge capacity of 2212 mAh/g at 1 mA/cm2. These ground-breaking performances could be attributed to the synergistic effect of the photocatalytic and electrocatalytic activities of SQD photocatalysts with the ideal conduction band/valence band values, the abundant defective sites, and the stronger O2 and lower LiO2 adsorption strengths of SQD photocatalysts. These systematic research studies highlight the significance of SQD bifunctional photocatalysts and could be extended to other photocatalysts for further high-efficiency photoelectric conversion and storage.

Light-Assisted Metal-Air Batteries: Progress, Challenges, and Perspectives

Metal-air batteries are considered one of the most promising next-generation energy storage devices owing to their ultrahigh theoretical specific energy. However, sluggish cathode kinetics (O₂ and CO₂ reduction/evolution) result in large overpotentials and low round-trip efficiencies which seriously hinder their practical applications. Utilizing light to drive slow cathode processes has increasingly becoming a promising solution to this issue. Considering the rapid development and emerging issues of this field, this Review summarizes the current understanding of light-assisted metal-air batteries in terms of configurations and mechanisms, provides general design strategies and specific examples of photocathodes, systematically discusses the influence of light on batteries, and finally identifies existing gaps and future priorities for the development of practical light-assisted metal-air batteries.

Metal-air batteries: progress and perspective

The metal-air batteries with the largest theoretical energy densities have been paid much more attention. However, metal-air batteries including Li-air/O₂, Li-CO₂, Na-air/O_2, and Zn-air/O₂ batteries, are complex systems that have their respective scientific problems, such as metal dendrite forming/deforming, the kinetics of redox mediators for oxygen reduction/evolution reactions, high overpotentials, desolution of CO₂, H₂O, etc. from the air and related side reactions on both anode and cathode. It should be the main direction to address these shortages to improve performance. Here, we summarized recently research progress in these metal-air/O₂ batteries. Some perspectives are also provided for these research fields.

Photo-Assisted Metal-Air Batteries: Recent Progress, Challenges and Opportunities

To meet the need of high energy density, long durability, safe and cost-efficient energy conversion and storage devices, metal-air batteries like Li-O₂ and Zn-O₂ batteries have received enormous attention and were subject to exciting development in the past decade. Photo-assisted strategies that enable the effective combination of photo/electric energy conversion/storage render a new dimension for the conventional metal-air batteries techniques with mere electric energy utilization. Therefore, tremendous research is ongoing in search of more efficient and durable devices with photo-assisted strategies. This review provides an overview of photo-assisted Li-O₂ batteries, Zn-O₂ batteries, and batteries with various metal/air components. The working mechanism, the basic device architecture and practical performances of various photo-assisted systems are summarized and discussed. Furthermore, certain technical challenges and future opportunities for the photo-assisted metal air batteries are emphasized and discussed in the hope of stimulating further research.

Tailored Plasmonic Ru/OV-MoO2 on TiO2 Catalysts via Solid-Phase Interface Engineering: Toward Highly Efficient Photoassisted Li-O2 Batteries with Enhanced Cycling Reliability

The photoassisted electrochemical reactions are considered an effective method to reduce the overpotential of Li-O₂ batteries. However, achieving long-term cell cycling stability remains a challenge. Here, we report a solid-phase interfacial reaction (SPIR) strategy that introduces both oxygen vacancies (O_V) and metal centers (Ru) into the MoO₂ to synthesize the surface plasmon (i.e., Ru/O_V-MoO₂). Then, Ru/O_V-MoO₂ can be uniformly loaded on the TiO₂ nanowires by the hydrothermal method. The plasma effect of Ru/O_V-MoO₂ demonstrates the effective reduction of the photoexcited electron and hole recombination to improve visible light-harvesting ability. The lifetime of electrons and holes can be extended by Ru nanoparticles, which is beneficial for promoting the formation and decomposition of Li₂O₂. In addition, the generated O_V further enhanced the migration of electrons and Li⁺, thus improving the ORR performance. The Ru/O_V-MT/CC cathode corroborates excellent stability and catalytic performance in the photoassisted Li-O₂ battery, with an overpotential value of 0.47 V, achieving the highest energy efficiency of 93.94%, retaining at 89.13% after 800 h. This work offers a platform for preparing a stable, bifunctional catalyst with the high total activity of a photoassisted Li-O₂ battery.

Role of chemistry in bio-inspired liquid wettability

Chemistry and topography are the two distinct available tools for customizing different bio-inspired liquid wettability including superhydrophobicity, superamphiphobicity, underwater superoleophobicity, underwater superoleophilicity, and liquid infused slippery property. In nature, various living species possessing super and special liquid wettability inherently comprises of distinctly patterned surface topography decorated with low/high surface energy. Inspired from the topographically diverse natural species, the variation in surface topography has been the dominant approach for constructing bio-inspired antiwetting interfaces. However, recently, the modulation of chemistry has emerged as a facile route for the controlled tailoring of a wide range of bio-inspired liquid wettability. This review article aims to summarize the various reports published over the years that has elaborated the distinctive importance of both chemistry and topography in imparting and modulating various bio-inspired wettability. Moreover, this article outlines some obvious advantages of chemical modulation approach over topographical variation. For example, the strategic use of the chemical approach has allowed the facile, simultaneous, and independent tailoring of both liquid wettability and other relevant physical properties. We have also discussed the design of different antiwetting patterned and stimuli-responsive interfaces following the strategic and precise alteration of chemistry for various prospective applications.

Boosting Cycling Stability and Rate Capability of Li-CO2 Batteries via Synergistic Photoelectric Effect and Plasmonic Interaction

Sluggish CO₂ reduction/evolution kinetics at cathodes seriously impede the realistic applications of Li-CO₂ batteries. Herein, synergistic photoelectric effect and plasmonic interaction are introduced to accelerate CO₂ reduction/evolution reactions by designing a silver nanoparticle-decorated titanium dioxide nanotube array cathode. The incident light excites energetic photoelectrons/holes in titanium dioxide to overcome reaction barriers, and induces the intensified electric field around silver nanoparticles to enable effective separation/transfer of photogenerated carriers and a thermodynamically favorable reaction pathway. The resulting Li-CO₂ battery demonstrates ultra-low charge voltage of 2.86 V at 0.10 mA cm^-2 , good cycling stability with 86.9 % round-trip efficiency after 100 cycles, and high rate capability at 2.0 mA cm^-2 . This work offers guidance on rational cathode design for advanced Li-CO₂ batteries and beyond.

Internal Electric Field and Interfacial Bonding Engineered Step-Scheme Junction for a Visible-Light-Involved Lithium-Oxygen Battery

Li-O₂ batteries have aroused considerable interest in recent years, however they are hindered by high kinetic barriers and large overvoltages at cathodes. Herein, a step-scheme (S-scheme) junction with hematite on carbon nitride (Fe₂ O₃ /C₃ N₄ ) is designed as a bifunctional catalyst to facilitate oxygen redox for a visible-light-involved Li-O₂ battery. The internal electric field and interfacial Fe-N bonding in the heterojunction boost the separation and directional migration of photo-carriers to establish spatially isolated redox centers, at which the photoelectrons on C₃ N₄ and holes on Fe₂ O₃ remarkably accelerate the discharge and charge kinetics. These enable the Li-O₂ battery with Fe₂ O₃ /C₃ N₄ to present an elevated discharge voltage of 3.13 V under illumination, higher than the equilibrium potential 2.96 V in the dark, and a charge voltage of 3.19 V, as well as superior rate capability and cycling stability. This work will shed light on rational cathode design for metal-O₂ batteries.

Photoelectrochemistry of oxygen in rechargeable Li-O2 batteries

Rechargeable lithium-oxygen (Li-O₂) batteries are promising energy storage devices due to their high theoretical energy density. However, the sluggish kinetics of the oxygen reduction and evolution reactions (ORR/OER) at the cathodes results in large polarization and low energy efficiency. Although advances have been achieved in electrode material designs and battery configurations, large discharge/charge voltage gaps remain. The introduction of light into Li-O₂ batteries has been demonstrated to boost the reaction kinetics of the ORR/OER, leading to enhanced electrochemical performances, but the understanding of the photoelectrochemical process at oxygen cathodes is limited. This tutorial review focuses on the recent findings regarding photoinvolved oxygen cathodes, battery configurations, and the stability of Li-O₂ batteries, aiming to provide a fundamental understanding of photoinvolved Li-O₂ batteries. The challenges and perspectives are discussed in light of the interdisciplinary nature of photochemistry, materials chemistry, electrochemistry, computation, spectroscopy, and surface science.

Photoelectrochemical energy storage materials: design principles and functional devices towards direct solar to electrochemical energy storage

Advanced solar energy utilization technologies have been booming for carbon-neutral and renewable society development. Photovoltaic cells now hold the highest potential for widespread sustainable electricity production and photo(electro)catalytic cells could supply various chemicals. However, both of them require the connection of energy storage devices or matter to compensate for intermittent sunlight, suffering from complicated structures and external energy loss. Newly developed photoelectrochemical energy storage (PES) devices can effectively convert and store solar energy in one two-electrode battery, simplifying the configuration and decreasing the external energy loss. Based on PES materials, the PES devices could realize direct solar-to-electrochemical energy storage, which is fundamentally different from photo(electro)catalytic cells (solar-to-chemical energy conversion) and photovoltaic cells (solar-to-electricity energy conversion). This review summarizes a critically selected overview of advanced PES materials, the key to direct solar to electrochemical energy storage technology, with the focus on the research progress in PES processes and design principles. Based on the specific discussions of the performance metrics, the bottlenecks of PES devices, including low efficiency and deteriorative stability, are also discussed. Finally, several perspectives of potential strategies to overcome the bottlenecks and realize practical photoelectrochemical energy storage devices are presented.

A Dual Photoelectrode Photoassisted Fe-Air Battery: The Photo-Electrocatalysis Mechanism Accounting for the Improved Oxygen Evolution Reaction and Oxygen Reduction Reaction of Air Electrodes

Effective utilization of solar energy in battery systems is a promising solution to achieve sustainable and green development. In this work, a photoassisted Fe-air battery (PFAB) with two photoelectrodes of ZnO-TiO₂ heterostructure and polyterthiophene (pTTh)-coated CuO (pTTh-CuO) grown on fluorine-doped tin oxide (FTO) is proposed. The band structure of semiconductors and the charge-transfer mechanism of heterostructure are studied. The electrochemical results show that the photogenerated electrons and holes play key roles in reducing the oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) overpotential in the discharging and charging processes, respectively. The short-circuit current density, the open-circuit voltage, and the maximum power output of the PFAB can reach 34.28 mA cm^-2 , 1.15 V, and 5.69 mW cm^-2 upon illumination, respectively. The photoassisted Fe-air battery exhibits a low charge voltage of 0.64 V for ZnO-TiO₂ as photoelectrode and a discharge voltage of 1.38 V for pTTh-CuO as a photoelectrode at 0.1 mA cm^-2 .

Nonvolatile and Nonflammable Sulfolane-Based Electrolyte Achieving Effective and Safe Operation of the Li-O2 Battery in Open O2 Environment

The Li-O₂ battery should operate effectively/safely in an open O₂ environment for practical applications, but not trapped in sealed/closed atmosphere. However, the typical use of volatile and flammable electrolyte restricts Li-O₂ battery to be able to be running in open O₂ environment. We report herein, for the first time, a highly electrochemical reversible Li-O₂ battery operated in an open O₂ environment, i.e., under the condition of keeping O₂ flowing continuously based on a nonvolatile and nonflammable sulfolane (TMS) solvent. The electrochemical irreversibility of Li₂O₂/O₂ conversion and incompatibility between Li metal anodes and electrolyte have been addressed via dissolving LiNO₃ in concentrated TMS electrolyte. The tuned electrolyte not only enables a stable solid electrolyte interphase (SEI) with conformal inorganic components (including LiF, LiN_xO_y, and Li₂O) that promotes a uniform Li electro-plating/stripping process but also results in a low charge overpotential, a stable discharge terminal plateau, and reversible O₂ generation of the Li-O₂ battery conducted in an open O₂ environment.

A long life solid-state lithium-oxygen battery enabled by durable oxygen deficient flower-like CeO2 microspheres based solid electrolyte

Rechargeable lithium-oxygen batteries (Li-O2) are one of the most promising candidates for energy storage and electric vehicles due to their high energy density. Nevertheless, their realistic applications are frequently restricted...

Interface engineering of hierarchical P-doped NiSe/2H-MoSe2 nanorod arrays for efficient hydrogen evolution

Developing non-noble metal-based electrocatalysts with better activity and stability for hydrogen evolution reaction (HER) is crucial for the electrolysis of water. Herein, self-supported three-dimensional (3D) P-doped NiSe/2H-MoSe2 nanorod arrays (denoted...

Manipulating Ru oxidation within electrospun carbon nanofibers to boost hydrogen and oxygen evolution for electrochemical overall water splitting

1D bifunctional RuO2/Ru-CNFs-350 catalyst is fabricated to show high activity and remarkable durability toward both OER and HER due to the formation of a RuO2/Ru heterostructure and the carbon substrate.

Molybdenum and cobalt co-doped VC nanoparticles encapsulated in nanocarbon as efficient electrocatalysts for the hydrogen evolution reaction

Molybdenum and cobalt co-doped VC nanoparticles encapsulated in nanocarbon (Mo, Co-VC@C) are successfully synthesized via a one-pot calcination route, exhibiting excellent electrocatalytic HER performance.

High-Efficiency and Stable Li-CO2 Battery Enabled by Carbon Nanotube/Carbon Nitride Heterostructured Photocathode

Li-CO₂ batteries are explored as promising power systems to alleviate environmental issues and to implement space applications. However, sluggish cathode kinetics of CO₂ reduction/evolution result in low round-trip efficiency and poor cycling stability of the fabricated energy-storage devices. Herein, we design a heterostructued photocathode comprising carbon nanotube and carbon nitride to accelerate cathode reactions of a Li-CO₂ battery under illumination. Benefiting from the unique defective structure of carbon nitride and favorable interfacial charge transfer, the photocathode effectively harvests ultraviolet-visible light to generate abundant photoexcited carriers and coordinates energetic photoelectrons/holes to participate in the discharge/charge reactions, leading to efficient photo-energy utilization in decreasing reaction barriers and enhancing thermodynamic reversibility of Li-CO₂ battery. The resulting battery delivers a high round-trip efficiency of 98.8 % (ultralow voltage hysteresis of 0.04 V) and superior cycling stability (86.1 % efficiency retention after 100 cycles).

Stabilizing Li Anodes in I2 Steam to Tackle the Shuttling-Induced Depletion of an Iodide/Triiodide Redox Mediator in Li-O2 Batteries with Suppressed Li Dendrite Growth

Redox mediators (RMs) have become a significant point in the now-established Li-O₂ battery system to reduce the charging overpotential in the oxygen evolution process. Nevertheless, a major inherent barrier of the RM is the redox shuttling between the Li metal anode and mobile RM, resulting in the corrosion of Li and depletion of RM. In this study, taking iodide/triiodide as a model RM, we propose an effective strategy by immersing the Li metal anode in I₂ steam to create a 1.5 μm thick surface protective layer. The resultant ionic conductive LiI layer on the Li metal anode can not only suppress Li dendrite growth but also act as a buffer layer between the RM and bare Li. By combining the iodide/triiodide RM with the LiI protective layer, the Li-O₂ battery shows low and steady charge voltage plateaus of ∼3.6 V over 70 cycles. Importantly, the symmetrical cell using the LiI-protected Li electrode exhibited small Li plating/stripping overpotentials (∼20 mV, 480 h), far superior to that of the bare Li electrode (∼70 mV, 300 h). The in situ interfacial observation shows that dendrite growth on the Li metal can be effectively suppressed by optimizing the LiI protective layer.

Molybdenum Disulfide-Zinc Oxide Photocathodes for Photo-Rechargeable Zinc-Ion Batteries

Systems for harvesting and storing solar energy have found practical applications ranging from solar farms to autonomous smart devices. Generally, these energy solutions consist of solar cells for light harvesting and rechargeable batteries to match the solar energy supply to consumption demands. Rather than having a separate energy harvesting and storing device, we report photo-rechargeable zinc-ion batteries (hν-ZIBs) using a photoactive cathode composed of layer-by-layer grown zinc oxide and molybdenum disulfide. These photocathodes are capable of harvesting solar energy and storing it in the same material and alleviate the need for solar cells or power converters. The proposed photocathodes achieve photoconversion efficiencies of ∼1.8% using a 455 nm light source and ∼0.2% of solar-conversion efficiencies. Light not only allows photocharging but also enhances the battery capacity from 245 to 340 mA h g^-1 (specific current of 100 mA g^-1 and 12 mW cm^-2 light intensity at 455 nm). Finally, the proposed hν-ZIBs also demonstrate a capacity retention of ∼82% over 200 cycles.

Boosting the electrochemistry of Li2O2 in lithium–oxygen batteries by plasmon-induced hot-electron injection

A light-assisted lithium–oxygen battery is constructed to improve the kinetics of the ORR and OER with a semiconductor–metal composite cathode material.