EnergyChem最新文献

Transmission electron microscopy (TEM) is widely used in the materials science community because of its high spatial, temporal and energy resolution. However, for electron beam-sensitive halide perovskites (HPs), the achievements offered by TEM are still in their infancy due to the nonnegligible structural damage caused by the incident electron beams to the fragile structure. Despite these challenges, the potential for TEM to provide unique insights into the microstructure and phase evolution of HPs at the atomic scale, to track the dynamic ion migration behaviors, and to explore the effects of lattice defects on physicochemical properties is still fascinating. In this review, we summarize recent achievements in HPs through advanced analytical methods embedded in the TEM, including high-resolution/scanning TEM (HRTEM/STEM) imaging, electron diffraction (ED) analysis, X-ray energy dispersive spectroscopy (EDS), and electron energy-loss spectroscopy (EELS) measurement, and in-situ TEM observation, with the aim of providing a multi-dimensional and multi-scale understanding of the intrinsic properties of HPs that have not yet been discovered. In addition, we delve into the inherent beam-damage mechanisms affecting the delicate HPs crystal, thereby emphasizing the significant hurdles associated with employing TEM in HPs research. Finally, we present a number of effective strategies that may be beneficial in reducing the damage caused by beams. In particular, the introduction of a direct-detection electron-counting (DDEC) camera has contributed significantly to the advancement of low-dose imaging and the suppression of beam damage to the intrinsic structure of HPs. With the improvement of low-dose imaging technology, TEM characterization is expected to promote a comprehensive understanding of the intrinsic properties of HPs in terms of structure-property-performance and to expand the wide range of applications of HPs in optoelectronic devices.

Ni-rich layered transition metal oxides possess remarkably high capacity and thus are very competitive cathode materials in high-energy lithium-ion batteries (LIBs) for electric vehicles, but encounter the critical problems of fast degradation caused by the highly reactive nickel component. Here in this review we intensively summarize thedegradation mechanism of Ni-rich cathode materials including e.g., residual lithium species, cation mixing, gas generation, surface structure reconstruction, crack, thermal instability, and transition metal dissolution. Furthermore, the state-of-art strategies e.g., new preparation methods, single-crystal, doping, structure design, coating and new binders, to tackle these degradation problem are accounted. This review might be inspiring for better understanding the degradation mechanism and relevant coping approaches of high-energy cathode materials for lithium ion batteries.

The ongoing surge in demand for energy conversion and storage spurs the development of high-efficiency batteries. In recent decades, aqueous alkaline batteries (AABs) have been the focus point owing to the high safety, low cost, environmental benefits, impressive output voltage and theoretical energy density. However, the large-scale application of AABs is hindered by the poor cyclability and insufficient capacity utilization, especially in anodes. To circumvent the issues, great research efforts have been dedicated to the electrode design and electrolyte optimization. In this review, reaction mechanisms, modification strategies, application feasibility and existing challenges are systematically summarized and highlighted. Additionally, insightful perspectives and research orientations are proposed for further development of AABs anodes.

Electrochemical water splitting, especially in acidic media, is a promising technology for hydrogen production and sustainable energy conversion. However, it remains a challenge to synthesize suitable acidic oxygen evolution reaction (OER) electrocatalysts that provide high activity and long-term stability according to the industrial standards. Up to date, quite few reviews provide a systematic summarization of the strategies and approaches to improve the electrocatalytic performances of the catalysts in acidic electrolytes. Herein, we analyze the electrochemical behavior of the reported state-of-the-art OER catalysts and provide a comprehensive review of the systematic strategies for preparing high-performance electrocatalysts. First, we introduce some fundamentals of OER mechanism to give readers a deeper understanding of this field. Then, we summarize and discuss various design strategies, including electronic state modulation, structural manipulation, etc. Finally, the challenges, opportunities, and future outlook regarding acidic OER electrocatalysts are delivered. This review will serve as a useful guiding resource for researchers seeking in-depth understanding of the OER mechanism in acidic media as well as learning approaches for synthesizing highly efficient and cost-effective OER electrocatalysts.

Synthetic porous carbons (SPCs) are important materials in fundamental research and industrial applications due to their diverse structures at different dimensions, intriguing physio-chemical properties, exceptional thermal and chemical stability, etc. In particular, the features including high electron conductivity, accessible active surface/interface, and developed porosity warrant their superior performances in clean energy storage and conversion. In this review, we summarize the latest advances in SPCs, serving as electrodes for this ever-increasing energy storage and conversion-related directions, e.g., supercapacitors, rechargeable batteries, fuel cells, etc. We emphasized rational design and targeted synthesis of SPCs based on bottom-up strategy, the effective methods for precise tuning of their core parameters, and the disclosure of their structure-performance correlations. The challenges of fine-tuning surface chemistry by doping heteroatoms, engineering defective sites, and optimizing compositions are discussed, which could endow the SPCs with new functions and potential applications. Finally, we outlined the developing trend and design principle of the new generation of SPCs for clean energy storage and conversion. We expect that this review could inspire interdisciplinary activities between the synthesis, physical and chemical studies of SPCs and other potential applications in addition to energy storage and conversion.

With the rapid development of nuclear industry, effective management of nuclear waste and oversight of nuclear fuel cycle are critical. Radionuclides such as uranium (U), plutonium (Pu), neptunium (Np), americium (Am), curium (Cm), technetium (Tc), rhenium (Re), iodine (I), selenium (Se), thorium (Th), cesium (Cs), and strontium (Sr) transferred into environment are dangerous. It is crucial to design the corresponding materials to exhibit high adsorption capacity and selectivity among competing species in nuclear waste. Herein, this review comprehensively summarizes the application of advanced porous materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and amorphous porous organic polymers (POPs) as porous adsorbents for radionuclides removal. These porous materials feature uniform composition, large porosity, and good stability, which lay a good foundation for various applications. The tunable pore sizes, high specific surface areas, exchangeable sites, and functional groups are designed as accessible platforms for nuclides diffusion and adsorption. Specific binding mechanisms toward various radionuclides, such as complexation, electrostatic interaction, and ion exchange are presented. Beyond traditional adsorbents, the superior capacity, kinetics, selectivity, and reusability of COFs, MOFs, and POPs make them broad application prospects in radionuclides removal, providing a way for effective applications in environmental remediation.

In the past few decades, renewable-energy-driven fuel cell technologies have been widely investigated as promising approaches to alleviate the energy and environmental crisis caused by fossil fuel consumption. Similar to hydrogen, ammonia provides a potential solution due to its comparable energy density and carbon-free emissions. Besides, the convenient storage and transportation of ammonia make the direct ammonia fuel cell (DAFC) a more secure technology than the hydrogen-based fuel cell system. However, the sluggish kinetics of ammonia oxidation reaction significantly hindered the performance of low-temperature DAFCs, urgently demanding systematic guidance for designing high-efficiency electrocatalysts. In this review, with an in-depth study of the basic principle of DAFC and the mechanism of AOR, we systematically summarized and discussed the recently reported strategies for developing high-performance AOR electrocatalysts, including size regulating, crystal facet engineering, morphology controlling, defect engineering, alloying, heterostructure constructing, and molecular engineering strategies. Finally, we propose perspectives and challenges for future AOR electrocatalyst development and high-performance DAFC construction. We hope this review could provide significant insights into fabricating active and stable AOR electrocatalysts for practical low-temperature DAFC.

The constant pursuit of alternative energy sources stimulates the rapid exploitation of energy storage systems. Compared to alkali metal-ion batteries, aqueous transition-metal ion batteries have captured increasing attention because of their high safety, eco-friendliness, abundant resources, and low cost. More importantly, their multivalent chemistry offers opportunities to realize storage technologies with higher energy. Although these bright prospects have fostered progress in recent years, practical deployment of these batteries has been denied by several scientific and technological issues including sluggish reaction kinetics, poor electrochemical reversibility, and low material stability. In this comprehensive overview, we focus on the materials and electrochemistry of several booming aqueous transition-metal ion batteries such as Zn, Cu, Fe, and Mn-ion systems. State-of-the-art progress accompanied with the solutions to addressing the above-mentioned issues are highlighted. A particular focus is laid on zinc-ion batteries, which are ready to become commercially available. Finally, the remaining challenges and future directions in the field are also outlined. We anticipate that this review will supply a clear understanding of the current status and meaningful guidelines for researchers in developing aqueous transition-metal ion batteries.

The development of clean sustainable energy conversion technologies to deal with energy shortage and environmental pollution has aroused a widespread concern. To improve the rate and selectivity of the pivotal chemical reactions involved in these technologies, high-performance electrocatalysts are crucial. Alloys have sparked research hotspot in electrocatalysis because of their higher catalytic activity, stability, and selectivity than their single-metal counterparts. In this review, the design strategies for alloy electrocatalysts are firstly introduced with a focus on how to achieve optimal performance by composition regulation, size optimization and morphology control. Subsequently, we offer a comprehensive overview of the electrocatalytic applications of binary, ternary, quaternary, and high-entropy alloys to different types of electrochemical energy conversion processes, including the hydrogen evolution, oxygen evolution, oxygen reduction, CO₂ reduction, formic acid oxidation, methanol oxidation, and ethanol oxidation reactions. Finally, the challenges and future outlook are presented for the rational design of advanced alloy electrocatalysts.

Electrocatalytic water splitting for green hydrogen generation is of great significance for renewable energy conversion and storage. The development of efficient electrocatalysts to reduce the energy barriers of the two half-reactions of hydrogen evolution (HER) and oxygen evolution (OER) is the key to realize the high-efficiency industrialization of electrochemical water splitting. With the continuous investment of research efforts, diverse transition metal-based catalysts have flourished, and their dynamic structural reconstruction during electrocatalytic OER and HER has also been pushed into a research upsurge. Since most transition metal compounds are thermodynamically unstable under electrochemical OER or HER conditions, they tend to undergo dynamic structural evolution to reach a relatively stable state, whereby the in situ reconstructed surface as the real reactivity species induces the changes in catalytic activity, which brings challenges to understanding the real catalytic mechanism and also motivates the development of surface reconstruction as a novel strategy to design superior heterostructure catalysts. At present, how to rationally utilize surface reconstruction to achieve breakthroughs in catalytic performance has become a critical focus area. This review summarizes the recent progress of surface reconstruction-derived heterostructures for electrocatalytic OER and HER, highlighting the fundamental understanding of surface reconstruction behaviors, the correlation between the intrinsic structure and dynamic reconstruction process of pristine catalysts, and some possible catalytic mechanisms that responsible for the enhanced catalytic activity. Moreover, several instructive design strategies of catalysts for modulating structural reconstruction to obtain optimized activity including heteroatom doping/substitution, anion/cation induction, structural defects, and heterostructure construction, are then introduced. Finally, we put forward the challenges and outlooks for surface reconstruction engineering, providing new insights and directions for future research development.