EcoEnergy最新文献

Energy storage and conversion (ESC) devices are regarded as predominant technologies to reach zero emission of carbon dioxide, which still face many challenges, such as poor safety, limited cycle life, low efficiency, etc. Hexagonal boron nitride (h-BN), distinguished by its robust mechanical strength, chemical inertness, exceptional thermal stability, and superior ion conductivity, has appeared to meet some challenges of ESC devices. Typically, h-BN can act as a perfect modifier to enhance the safety of batteries by improving the mechanical strength and heat dissipation of separators, extend cycle life of Li metal batteries by protecting solid state electrolyte from reducing and increase efficiency of fuel cells by improving the proton conductivity of membranes. Besides, recent progress on doping, surface modification, tailoring quantum dots, heterostructures, and hybridizations with other nanomaterials has made it possible to extensively apply h-BN to other ESC technologies. This review provides a comprehensive overview of the up-to-date synthetic strategies for BN-based materials and discusses the most recent breakthroughs on their application in electrochemical ESC technologies. Also, the challenges and future development for BN-based materials in these fields are assessed.

Solid-state bismuth telluride-based thermoelectric devices enable the generation of electricity from temperature differences and have been commercially applied in various fields. However, in many scenarios, the surface of the heat source is not flat. Therefore, it is crucial to develop flexible thermoelectric materials and devices to efficiently utilize heat sources and expand their applications. Compared with organic thermoelectric materials and devices, inorganic flexible thermoelectric materials and devices have much higher thermoelectric performance and stability. Considering the rapid development in this research field, we carefully summarize the design principles, structures, and thermoelectric properties of inorganic flexible materials and their devices reported in the recent 3 years, including sulfides, selenides, tellurides, and composite materials designed based on these inorganics. The structural designs of flexible thermoelectric devices based on micro-sized bulk materials are also carefully summarized. Additionally, we overview the mechanical stability and methods for reducing internal resistance for designs of inorganic flexible thermoelectric devices. In the end, we provide outlooks on future research directions for inorganic flexible thermoelectric materials and devices. This review will help guide thermoelectric researchers, beginners, and students.

Extensive consumption of limited fossil fuel resources generates serious environmental problems, such as release of large amounts of the greenhouse gas CO₂. It is, therefore, urgently necessary to look for alternative energy resources to meet increasing energy demands. Hydrogen is a clean, environmentally friendly, and sustainable energy source. Electrochemical water splitting is one of the cleanest and greenest technologies available for hydrogen production. Unfortunately, large-scale water electrolysis is hindered by the high costs of catalysts, since noble metal-based materials have been demonstrated to be the best catalysts (e.g., Pt for the cathode and Ru/Ir-oxide for the anode catalyst). Recently, transition metal carbides (TMCs) have drawn significant attention for use in electrochemical water splitting, especially for hydrogen evolution reactions, owing to their high intrinsic catalytic activities, extraordinary electrical conductivities, and abundant source materials. TMCs exhibit Pt-like electronic structures and are considered suitable alternatives for Pt. This review systematically summarizes recent advances in the uses of representative TMCs for the electrochemical hydrogen and oxygen evolution reactions and highlights advantages in the electrocatalytic effects provided by nanostructuring. Finally, existing challenges and future perspectives for use of these electrocatalysts are discussed.

The long-term development of fossil energy has led to the destruction of carbon balance. Carbon capture technology needs to be used to reduce carbon emissions before clean energy completely replaces fossil energy. Metal-organic frameworks (MOFs), a porous crystalline material, show great potential in gas adsorption and has attracted great attention. The predictability of MOFs' structure and function also make it possible to use computational methods to advance and accelerate research. This review gives a brief overview of carbon dioxide capture and separation by MOFs, including adsorption and membrane separation. In the future, membrane separation technology is expected to be a crucial area of research for carbon capture applications due to its favorable characteristics such as high treatment efficiency and low carbon footprint, while mixed matrix membranes (MMMs) have been given more attention by scholars due to their lower cost and better separation performance. In summary, developing high-performance MOFs or MOF derivatives and researching more efficient separation methods, such as the application of MOF-based MMMs, should be the focus of future research by scholars in this field.

Cobalt–nickel layered double hydroxides (CoNi-LDHs) have been extensively synthesized through precipitation methods for their application in supercapacitors (SC). However, the influence of precipitant quantity on both morphology evolution and SC performance has been an underexplored area. This study systematically examines the morphological changes in CoNi-LDHs by varying the alkaline quantity and evaluates the performance of asymmetric SC. The findings reveal a progressive transformation in the morphology of CoNi-LDHs with an increase in alkaline content, starting from nanorod (Co₁Ni₂(OH)₂-1HMA), progressing to nanorod/nansosheet composite (Co₁Ni₂(OH)₂-4HMA), and ultimately evolving into nanosheet (Co₁Ni₂(OH)₂-8HMA). This evolution is attributed to the synergetic effect of the precipitant and variable cobalt, which provides multiple valences and induces morphology evolution. The resulting LDHs demonstrate different SC performances: (1) Co₁Ni₂(OH)₂-1HMA exhibits a maximum capacitance of 1764 F/g, while Co₁Ni₂(OH)₂-4HMA and Co₁Ni₂(OH)₂-8HMA show values of 1460 F/g and 1676 F/g, respectively; (2) rate capabilities showcase percentages of 60.5% for Co₁Ni₂(OH)₂-1HMA, 83.1% for Co₁Ni₂(OH)₂-4HMA, and 66.3% for Co₁Ni₂(OH)₂-8HMA; (3) maximum energy densities are recorded at 72.1 Wh/kg for Co₁Ni₂(OH)₂-1HMA, 41.3 Wh/kg for Co₁Ni₂(OH)₂-4HMA, and 62.8 Wh/kg for Co1Ni₂(OH)₂-8HMA. Particularly, Co₁Ni₂(OH)₂-8HMA exhibits superlong cycling stability, retaining approximately 99% capacitance after 25000 consecutive charge/discharge cycles at 7.0 A/g. This result underscores its significant potential for efficient energy storage applications.

In the advancing world of graphene, highly anisotropic 2D semiconductor nanosheets, notable for their nanometer-scale thickness, have emerged as a leading innovation, displaying immense potential in the exploration of renewable and clean energy production. These have garnered significant attention from researchers. The nanosheets are marked by their extraordinary electronic, optical, and chemical attributes, positioning them as attractive foundational components for heterogeneous photocatalysts. This review diligently summarizes both the seminal work and ongoing developments pertaining to 2D semiconductor nanosheets and their application to solar energy within the context of heterogeneous photocatalysis. We begin by detailing the distinctive properties of 2D semiconductor nanosheets, concentrating on their pivotal roles in augmenting photocatalytic efficiency, and explaining the intrinsic mechanisms that govern the migration rate of photogenerated carriers on the material's surface. Subsequently, we delineate the methods employed to synthesize typical 2D semiconductor nanosheets. In alignment with the overarching objective of expanding light absorption capacity and accelerating charge transfer, we also examine the current research on the hybridization techniques involving 2D materials of varied dimensions, as well as their deployment in diverse photocatalytic applications. We conclude by identifying promising avenues and potential challenges that await further exploration in this burgeoning field.

Graphite carbon nitride (g-C₃N₄) nanotubes have received extensive attention due to its unique morphology and electronic migration. Herein, the defective porous g-C₃N₄ nanotube (DTCN) is prepared through a simple thermal reduction process. The construction of N vacancy and tubular structure can synergistically promote the separation of photogenerated charge carriers. As a result, DTCN demonstrates a higher photocatalytic hydrogen evolution rate (1440 μmol·g⁻¹·h⁻¹), which is 5 times higher than that of the initial g-C₃N₄ nanotube (TCN). Importantly, combined with density functional theory calculations and experimental results, it is the first time to prove that the synergy of curvature effect and N vacancy of nanotubes can enhance the adsorption energy of hydrogen and decrease the work function, resulting in more superior photocatalytic performance than the layered structure. This work provides more in-depth comprehension for the photocatalytic mechanism of nanotube materials, which has inspirational significance for the design of the g-C₃N₄ photocatalyst with high performance.

Introducing oxygen atoms into nickel-based alloys is an effective strategy for constructing water dissociation sites for hydrogen evolution reaction (HER). However, controlling oxygen content to realize the best match of water dissociation and hydrogen adsorption is challenging. Herein, we exploit the self-integration process of MoNi alloy in molten salts to introduce oxygen atoms, which ultimately leads to the localized generation of robust NiO_xH_y around the MoNi alloys. Interestingly, Mo is further doped into NiO_xH_y (Mo-NiO_xH_y) to construct an effective active center for water dissociation due to the high mobility in ionic solutions. Owing to the covering and space confinement of molten salt, MoNi alloy is exactly decorated with Mo-NiO_xH_y nanosheets. Both physical characterization and density functional theory calculation prove that the electron transport, water dissociation capability, and hydrogen adsorption of MoNi are finely tuned and benefited from the O and Mo doping, thus greatly expediting HER kinetics. Mo-NiO_xH_y exhibits a much lower overpotential of 33 mV at 10 mV cm⁻² in alkaline electrolyte, even superior to the Pt/C benchmark. Moreover, the final Mo-NiO_xH_y requires a low overpotential of 57 mV at 10 mV cm⁻² in acidic media. This enhancement is ascribed to the successful assembly of MoNi foam elicited by molten salt.

For secondary batteries, thermal runaway has become the main issue, and how to solve it is full of challenges. In this work, a universal thermal model for lithium ion batteries (LIBs) was proposed, which was validated by using commercially available 18650 batteries as well as testing the electrochemical parameters of a Poly(ethylene oxide)(PEO)–bis(trifluoromethane)sulfonimide lithium salt(LiTFSI)–Li₂MnO₃(LMO) (PLL) composite solid-state electrolyte (CSSE), while a computational model was developed for all-solid-state LIBs (ASSLIBs) based on PLL CSSE. The simulation results show that the maximum temperature of ASSLIBs based on PLL CSSE and commercial standards are both significantly lower than the thermal runaway temperature of solid-state electrolyte. However, as the temperature of the battery varies greatly under different operating conditions, it will cause great difficulties in the control of other ancillary components and even finally lead to certain safety issues. Therefore, from the perspective of performance and practical application, the CSSE should be improved toward improving the ionic conductivity at low temperatures to have more commercial prospects, and lower interfacial impedance and a higher lithium ion migration number would also be beneficial for optimizing the thermal behavior of ASSLIBs to achieve better commercial prospects.

Photoelectrochemical (PEC) water splitting with zero carbon emissions is a promising technology to solve the global issues of energy shortage and environmental pollution. However, the current development of PEC systems is facing a bottleneck of low solar-to-hydrogen (STH) efficiency (<10%), which cannot meet the demand of large-scale H₂ production. The development of low-cost, highly active, and stable photoanode materials is crucial for high STH efficiency of PEC water splitting. The recent development of BiVO₄ as photoanode materials for PEC water splitting has been a great success, and ABO₄-type ternary metal oxides with a similar structure to BiVO₄ have high development potential as efficient photoanodes for high-performance PEC water splitting. The design and development of ABO₄ photoanodes for PEC water splitting are critically reviewed with special emphasis on the modification strategies and performance improvement mechanisms of each semiconductor. The comprehensive analysis in this review provides guidelines and insights for the exploration of new high-efficiency photoanodes for solar fuel production.