In nanoscale metal particles,atoms of different elements can exhibit various condensed states:they may either fully mix to form homogeneous alloys or separate into distinct phases,creating heterogeneous structures.These diverse atomic arrangements significantly affect the electronic coupling and catalytic properties of the multimetallic nanoparticles.Precise control over the atomic condensed states within nanoparticles holds the promise of optimizing their electronic structures,offering significant opportunities for the design of novel nanocatalysts with distinctive properties.However,controlling atomic condensed states in nanoparticles using current wet-chemical methods remains challenging.In the synthesis of alloy nanomaterials,the intrinsic reduction potential differences between metal salts cause significant variations in reduction kinetics,making it difficult to achieve uniform alloying and precise control over the alloy compositions.In the synthesis of heterogeneous structures,the reduction potential differences cause galvanic replacement reactions between noble metal salts and less-stable metal nanostructures,limiting the controllability of nanocrystal growth.This paper reviews recent research progress in overcoming these synthesis limitations for controlled atomic condensed states of metal atoms in nanoparticles.Specifically,introducing an active hydrogen(i.e.,hydrogen atoms or radicals)interfacial reduction mechanism has mitigated the impact of reduction potential differences,improving the mixing homogeneity of different metal atoms within nanoparticles.This approach also allows precise control over the content of each metal component within nanoparticles.By modulating the reduction potentials of metal salts,it has become possible to suppress the galvanic replacement reaction between noble metal salts and less-stable metal nanostructures,leading to a novel family of core-shell nanostructures with a less-stable metal core and a noble metal shell.By precisely regulating the atomic condensed states within multimetallic metal nanoparticles,researchers have been able to effectively tune the electronic structures of these materials,significantly improving the catalytic performance.These advancements highlight the potential of controlled atomic condensed states in multimetallic nanoparticles for developing high-performance catalysts across various applications.
Novel and efficient techniques for low-cost and environmentally-friendly energy storage systems are imminent, in regard to the excessive consumption of non-renewable fossil energy. Hydrogen shows the advantages of high energy density, carbon neutrality and pollution-free, so it has been considered as a promising energy carrier to replace fossil fuels. However, the practical application of hydrogen is challenged by the low density, difficult storage and transportation. Therefore, efficient hydrogen storage materials for hydrogen are of great significance. Liquid organic hydrogen carriers (LOHCs) promote the release and absorption of hydrogen through chemical reactions, so it has attracted increasing attention. Lignin is the most abundant aromatic source of natural, renewable organic carbon on Earth. The technologies of converting lignin into LOHCs through catalytic upgrading meet the demands of "carbon neutrality" and have huge application potential. Therefore, we summarized here the recent research progress in the hydrodeoxygenation of lignin and its derivatives to LOHCs. The effects of different catalyst carriers on the catalytic performance for producing LOHCs were demonstrated. The application of the saturated products from lignin and its derivatives, which are considered to be promising LOHCs, was also reviewed. In addition, we also provided a prospect on the future technical development of the production of liquid hydrogen storage materials from lignin and its derivatives.
Proton exchange membrane fuel cells (PEMFCs), characterized by their high energy efficiency and environmental friendliness, are widely regarded as one of the most promising energy conversion technologies. However, the degradation and failure of the proton exchange membrane (PEM) remain key factors limiting the long-term durability and large-scale application of PEMFC systems. This study systematically reviews the three primary degradation modes of PEM-mechanical, thermal, and chemical degradation-from the perspectives of underlying mechanisms and mitigation strategies, with particular attention to their synergistic effects. The causes of these degradation modes during practical fuel cell operation, their impacts on the physicochemical structure of the membrane and on cell performance, as well as the current mitigation strategies and their limitations, are comprehensively analyzed. The results highlight that gas crossover serves as a critical link among different degradation processes: mechanical fatigue and crack propagation increase gas permeability, which intensifies chemical degradation through accelerated radical formation, while chemical degradation of the polymer backbone weakens the mechanical strength of the membrane, thereby promoting further mechanical failure and forming a vicious cycle. Finally, the study summarizes the existing challenges in PEM degradation research and proposes future directions, including the development of multi-stress coupled accelerated aging protocols, the establishment of quantitative correlations between gas permeability and membrane aging, the design of gradient composite membranes that combine durability with high electrochemical performance, and the optimization of system operation strategies to substantially extend overall lifetime and operational stability.
Accurate and real-time sensing is fundamental to advancements in health diagnostics,environmental monitoring,and industrial safety.However,conventional sensing materials such as metal oxides,conducting polymers,and carbon-based composites are constrained by intrinsic trade-offs between sensitivity,selectivity,and operational stability.To address these limitations,metal-organic frameworks(MOFs)have emerged as a transformative class of materials,offering unparalleled structural tunability,ultrahigh surface areas,and programmable pore chemistry.This comprehensive review provides an in-depth analysis of MOF-based chemiresistive sensors,moving beyond a simple catalog of examples to establish a mechanistic understanding of how molecular-level design dictates sensing performance.We systematically deconstruct the evolution from often-insulating pristine MOFs to advanced composites where MOFs synergize with conductive fillers like graphene,carbon nanotubes,and polymers and to MOF-derived porous carbons and metal oxides.Each category is critically examined to highlight strategies for overcoming inherent challenges in electrical conductivity,response kinetics,and long-term stability.The review is structured to guide the researcher in the field from fundamental design principles and charge transport mechanisms to performance benchmarking against key metrics such as sensitivity,limit of detection,selectivity,and response/recovery times.A significant focus is placed on the integration of MOFs into next-generation applications,including flexible and wearable electronics,multi-parameter sensor arrays,and intelligent systems that leverage artificial intelligence for pattern recognition and drift compensation.Furthermore,we critically address the pivotal challenges hindering practical deployment,such as hydrothermal/chemical stability,mechanical robustness for wearable formats,and the urgent need for standardized testing protocols.By synthesizing insights from fundamental research and cutting-edge applications,this review serves as a rational design guide and a forward-looking perspective,outlining a concrete roadmap for harnessing the full potential of MOFs in the development of intelligent,reliable,and commercially viable next-generation chemiresistive sensing technologies.
Photoelectrochemical (PEC) biosensors, as an emerging analytical platform, offer significant advantages, including low background signals, high sensitivity, and operational simplicity, due to the inherent separation of the excitation source and the detection signal. The core of achieving high performance in PEC biosensors lies in the development of efficient signal amplification strategies. This review systematically summarizes recent research progress on signal amplification mechanisms in PEC biosensors. Photoelectric dagger conversion constitutes the basis of PEC sensing, primarily involving three essential processes: light harvesting, charge carrier separation, and interfacial reaction. Based on this, the prevailing signal amplification mechanisms are reviewed from the core processes of photoelectric conversion to the design of signal output. Simultaneously, the design principles and characteristics of these mechanisms are delved. Finally, this review examines the challenges of PEC sensing technologies and explores future trends. This review aims to provide theoretical guidance for the rational design of high-performance PEC biosensors and to promote their further development in applications of analysis.
