Search Results (90)

The hydrogen evolution reaction (HER) is a cornerstone of green hydrogen production, yet its efficiency is constrained by the sluggish kinetics of water splitting. High-entropy catalysts (HECs), single-phase materials incorporating multiple principal elements, have emerged as a transformative solution. Their unique attributes including vast compositional flexibility, tunable electronic structures, and synergistic multi-element interactions, enable them to overcome the activity, stability, and cost limitations of conventional catalysts. Despite rapid performance advancements, the rational design of HECs is fundamentally hampered by critical knowledge gaps, particularly in identifying true active sites under operando conditions and predicting long-term stability. This work critically assesses these challenges, systematically summarizing the latest progress in HECs design, synthesis, and structure–activity relationships. By bridging fundamental principles with practical applications, we provide a forward-looking perspective on key research directions. Distinct from recent progress-focused reviews, this work establishes a strategic roadmap by systematically diagnosing seven grand challenges across the science-to-technology pipeline and proposing corresponding countermeasures. This framework aims to guide future research efforts toward the rational design and practical deployments of HECs for practical and cost-effective green hydrogen production. Full article

X ray photoelectron spectroscopy (XPS) is a key technique routinely employed for the chemical analysis of alloy surfaces, enabling precise nanoscale characterization of near surface elemental composition and chemical states. This review outlines the fundamental principles of XPS, typical data analysis workflows, and critical analytical considerations specific to alloy systems. Given the propensity for oxidation, multicomponent nature, and heterogeneous phase characteristics of alloys, standardized protocols are reviewed for sample preparation, binding energy calibration, peak fitting, quantitative analysis, and depth profiling. For conductive alloys, calibration using the Fermi edge or gold reference standards is specified, and the use of Auger parameters is highlighted to improve the reliability of chemical state identification. This article also systematically summarizes applications of XPS in corrosion protection, high temperature oxidation, surface modification, phase transformation, and failure analysis. It is emphasized that near surface chemical information must be validated in combination with bulk phase, microstructural, and electrochemical characterization to rationally establish relationships between surface chemistry and macroscopic performance. Finally, recent advances in near ambient pressure, in situ, high resolution, and intelligent XPS techniques are reviewed, providing a standardized reference and technical support for alloy research. Full article

Calcium–silicate–hydrate (C-S-H), the primary binding phase governing cement paste cohesion, undergoes progressive physicochemical transformation upon carbonation—a process that critically dictates concrete durability in atmospheric environments. When CO₂ penetrates the porous cement matrix, it triggers a cascade of degradation mechanisms: calcium leaching decalcifies the C-S-H structure, inducing polymerization of silicate chains from dimeric to longer-chain configurations, while concurrent precipitation of calcium carbonate and amorphous silica gel fundamentally reconstitutes the nanoscale architecture. These nanoscale alterations propagate to macroscopic property evolution, manifesting as initial strength and stiffness gains due to pore-filling carbonation products followed by eventual deterioration as the cohesive binding network deteriorates. This review synthesizes current understanding of carbonation-induced structural evolution, examining the coupled influences of environmental parameters—CO₂ concentration, relative humidity, and temperature—alongside C-S-H intrinsic chemistry (Ca/Si ratio, aluminum substitution, and alkali content) on reaction kinetics and material performance. However, significant knowledge gaps persist: predictive models for in-service carbonation rates remain elusive due to the disconnect between idealized laboratory conditions and the heterogeneous, cracked reality of field concrete; the causal linkage between nanoscale C-S-H alteration and macroscale cracking patterns along with physical performance is poorly resolved, and most mechanistic studies rely on synthetic C-S-H, neglecting the compositional complexity of real Portland cement systems. We further propose emerging protection strategies, including surface barrier coatings and low-carbon alternative binders (geopolymers, calcium sulfoaluminate cements, carbon-negative materials such as recycled cement), which demonstrate enhanced carbonation resistance. Future research priorities include developing effective coating barriers for carbonation protection, developing operando characterization techniques for real-time reaction monitoring, deploying machine learning algorithms to bridge atomistic simulations with structural-scale predictions, and establishing long-term field performance databases to validate laboratory-derived degradation models. Full article

Photocatalysts have emerged as a promising approach for the treatment of contaminated water, particularly for the removal of dyes and pharmaceutical residues that pose risks to human health. In addition, they can be employed for the generation of chemical fuels such as H₂ and oxidizers such as H₂O₂, which have been proposed as sustainable energy carriers to reduce reliance on fossil fuels. The first part of this brief review provides a detailed overview of the fundamental concepts of photocatalysis, including reaction pathways and reported mechanisms. The second part explores the main design strategies for enhancing photocatalytic performance, including morphology control and structural modification. Then, the third section highlights the benefits of theoretical modeling, including first-principles calculations and molecular simulations. The document culminates with a section on challenges and future perspectives, highlighting major issues in photocatalyst development such as large-scale synthesis, material stability, and reusability. This brief review is intended to provide young researchers with a concise understanding of the most effective strategies for enhancing photocatalytic performance, as well as the mechanisms influencing morphology and structural parameters. This work presents an integrated framework linking synthesis strategies, particle growth mechanisms, multidimensional nanostructures, in situ and operando characterization, and computational modeling to guide the rational design of next-generation photocatalysts. Full article

Two-dimensional (2D) heterostructures offer tunable electronic structures and synergistic interactions that enhance electrocatalytic activity beyond the limits of single-component materials. However, the same atomically thin interfaces that enable high performance also introduce inherent mechanical, chemical, and electronic vulnerabilities, giving rise to complex and coupled degradation pathways. In this review, we provide a systematic overview of degradation in 2D heterojunction electrocatalysts during electrochemical operation, covering failure mechanisms, operando characterization, and stabilization strategies. Degradation is governed by interfacial strain accumulation, bubble-induced stress and delamination, galvanic corrosion, and selective leaching, while stability can be improved through interfacial coupling, structural confinement, and controlled reconstruction. These insights provide practical design guidelines for developing robust 2D heterostructures for electrochemical energy conversion. Full article

Interest in further developments of the classical Fischer–Tropsch technology has increased in recent years. The development of processes capable of producing synthetic fuels has become a highly attractive research area due to the continuous global growth in energy demand. An extensive review covering the full development chain (from laboratory-scale experiments to pilot-scale studies and plant-level implementations) is therefore of significant relevance. Consequently, this review aims to be a reference by integrating findings across different development levels of Fischer–Tropsch synthesis technologies, thereby enabling a holistic perspective of the pathway toward industrial-scale deployment. The present work thus critically reviews recent advances in catalyst development, including the role of active phases, particle size effects, supports, and promoters, as well as the growing contribution of in situ and operando characterization techniques. In parallel, progress in kinetic and mechanistic modeling is discussed, highlighting both classical approaches and emerging data-driven and optimization-based methods. Different reactor technologies, from classical to novel technologies, are also analyzed with respect to hydrodynamics, heat and mass transfer limitations, and reactor intensification strategies. At the process level, the review assesses integrated and intensified Fischer–Tropsch-based routes, with particular emphasis on CO₂ utilization pathways, process integration, polygeneration schemes, and optimization frameworks. The potential of artificial intelligence and machine learning tools to accelerate catalyst discovery, reactor optimization, and process design is also addressed. Overall, this review identifies key technological advances, remaining challenges, and research gaps that must be addressed to enable economically viable and environmentally sustainable, and scalable Fischer–Tropsch processes to meet future energy demands. Full article

Anode-less battery architectures, which eliminate the host anode material, have attracted considerable attention as a promising approach to increase energy density, simplify cell manufacturing, and improve safety in next-generation energy storage systems. This review provides a structured and integrative overview on the current research landscape of anode-less cells, spanning both liquid- and solid-electrolyte technologies. It first introduces the fundamental principles, key advantages, and inherent challenges of the anode-less concept. Advanced characterization techniques, including electrochemical, interfacial, morphological, and operando approaches, are then discussed as essential tools for probing metal plating/stripping behavior and degradation mechanisms. The core of the review examines how system design governs performance, addressing strategies for liquid electrolytes, including current collector design, electrolyte formulation, and deposition control, as well as solid electrolytes, with an emphasis on interfacial engineering, fundamental limitations, and extensions to Na- and K-based batteries. By integrating insights across these systems, the review identifies critical challenges, including unstable solid-electrolyte interphases, dendrite formation, and interfacial contact loss. Finally, a development pyramid is introduced as a conceptual framework linking fundamental research to practical implementation, outlining key priorities from interface control and full-cell compatibility to long-term reliability while also highlighting industrial pathways toward hybrid and fully solid-state anode-less batteries. Full article

As a cornerstone of sustainable hydrogen generation, the hydrogen evolution reaction (HER) demands efficient, earth-abundant electrocatalysts to replace costly platinum benchmarks. Two-dimensional transition metal dichalcogenides (2D-TMDs) represent a highly promising class of non-precious materials for this application. This review provides a comprehensive analysis of recent progress in TMD-based HER catalysis. It begins by elucidating the intrinsic structural properties that underpin their catalytic potential, followed by a summary of key synthesis routes and characterization techniques. The central focus is on strategic engineering approaches to optimize TMD performance. Finally, we discuss persisting challenges and propose future research directions aimed at scalable production, advanced operando studies, and the design of bifunctional TMD catalysts for integrated water-splitting systems. Full article

Energy-Dispersive X-ray Diffraction (EDXRD) employs a polychromatic (white) X-ray beam and an energy-discriminating detector at a fixed scattering geometry to measure diffracted intensity as a function of photon energy. This technique enables the rapid acquisition of diffraction data over a wide range of d-spacings without mechanical scanning of the scattering angle, making it particularly valuable for time-resolved, bulk-penetrating, and operando studies. In this review, we provide a comprehensive overview of EDXRD, covering the fundamental principles and underlying physics, experimental methodologies and data analysis workflows, synchrotron white-beam implementations compared to monochromatic approaches, detector strategies, parameter optimization for accurate and efficient measurements, and representative applications in high-pressure science and battery research. Finally, we discuss current challenges and future prospects, including advances in detector technology, machine learning-assisted spectral analysis, and the development of standardized, automated EDXRD systems. Full article

Silicon is a well-known anode material for lithium-ion batteries that has attracted a lot of interests because of its high theoretical specific capacity (4200 mAh g⁻¹). However, its severe volume expansion during cycling leads to structural degradation and rapid capacity fading. The design of porous silicon architectures has emerged as a fundamental and effective strategy to mitigate these issues by accommodating mechanical stress and preserving electrode integrity. Concurrently, the development of advanced in situ/operando characterization techniques has shifted the research paradigm, enabling direct observation of dynamic structural and interfacial evolution under operating conditions. This review systematically summarizes recent progress in the rational design of porous Si-based anodes and critically examines how state-of-the-art in situ methods provide direct mechanistic validation of these designs. The work highlights the synergistic interplay between targeted material engineering and in situ/operando characterization, offering a roadmap for the development of high-performance porous silicon anodes. Full article

The catalytic hydrogenation of carbon dioxide (CO₂) represents a transformative approach for reducing greenhouse gas emissions while producing sustainable fuels and chemicals, with ethanol being particularly promising due to its compatibility with existing energy infrastructure. Despite significant progress in converting CO₂ to C₁ products (e.g., methane, methanol), selective synthesis of C₂₊ compounds like ethanol remains challenging because of competing reaction pathways and byproduct formation. Recent advances in thermo-catalytic CO₂ hydrogenation have explored diverse catalyst systems including noble metals (Rh, Pd, Au, Ir, Pt) and non-noble metals (Co, Cu, Fe), supported on zeolites, metal oxides, perovskites, silica, metal–organic frameworks, and carbon-based materials. These studies reveal that catalytic performance hinges on the synergistic effects of multimetallic sites, tailored support properties and controlled reaction micro-environments to optimize CO₂ activation, controlled hydrogenation and C−C coupling. Mechanistic insights highlight the critical balance between CO₂ reduction steps and selective C−C bond formation, supported by thermodynamic analysis, advanced characterization techniques and theoretical calculations. However, challenges persist, such as low ethanol yields and undesired byproducts, necessitating innovative catalyst designs and optimized reactor configurations. Future efforts must integrate computational modeling, in situ/operando studies, and renewable hydrogen sources to advance scalable and economically viable processes. This review consolidates key findings, proposes potential reaction mechanisms, and outlines strategies for designing high-efficiency catalysts, ultimately providing reference for industrial application of CO₂-to-ethanol technologies. Full article

Electrochemical CO₂ reduction (CO₂RR) is a promising route to transform a major greenhouse gas into value-added fuels and chemicals. However, its deployment is still hindered by the sluggish activation of CO₂, poor selectivity toward multielectron products, and competition with the hydrogen evolution reaction (HER). Single-atom catalysts (SACs) have emerged as powerful materials to address these challenges because they combine maximal metal utilization with well-defined coordination environments whose electronic structure can be precisely tuned through metal–support interactions. This minireview summarizes current understanding of how structural, electronic, and chemical features of SAC supports (e.g., porosity, heteroatom doping, vacancies, and surface functionalization) govern the adsorption and conversion of key CO₂RR intermediates and thus control product distributions from CO to CH₄, CH₃OH and C₂⁺ species. Particular emphasis is placed on selectivity descriptors (e.g., coordination number, d-band position, binding energies of *COOH and *OCHO) and on rational design strategies that exploit curvature, microenvironment engineering, and electronic metal–support interactions to direct the reaction along desired pathways. Representative SAC systems based primarily on N-doped carbons, complemented by selected examples on oxides and MXenes are discussed in terms of Faradaic efficiency (FE), current density and operational stability under practically relevant conditions. Finally, the review highlights remaining bottlenecks and outlines future directions, including operando spectroscopy and data-driven analysis of dynamic single-site ensembles, machine-learning-assisted DFT screening, scalable mechanochemical synthesis, and integration of SACs into industrially viable electrolyzers for carbon-neutral chemical production. Full article

Lithium iron phosphate (LiFePO₄, LFP) batteries dominate grid-scale energy storage, yet their cycle life is capped by its capacity fade issues. Conventional failure workflows suffer from redundant tests, high cost, and long turnaround time because the underlying mechanisms remain unclear. Herein, multi-scale characterization coupled with electrochemical tests have been quantitatively established to reveal four synergistic fade modes of LFP: active-Li loss, FePO₄ secondary-phase formation, SEI rupture, and particle fracture. A two-tier “screen–validate” protocol is proposed to accurately and efficiently disclose its mechanism. In the screening tier, capacity, cyclic voltammetry, electrochemical impedance spectroscopy, low-magnification scanning electron microscopy, and snapshot X-ray diffraction (XRD) rapidly flag the most probable failure cause. The validation tier then deploys mechanism-matched in situ/ex situ tools (operando XRD, TEM, XPS, ToF-SIMS, etc.) to build a comprehensive evidence chain of dynamic structural evolution, materials loss tracking, and quantitative proof. The streamlined workflow preserves scientific rigor and reproducibility while cutting analysis time and cost, offering a closed-loop route for fast failure diagnosis and targeted optimization of next-generation LFP batteries. Full article

As demand for high-performance energy storage grows across grid and mobility sectors, multivalent ion batteries (MVIBs) have emerged as promising alternatives to lithium-based systems due to their potential for higher volumetric energy density and material abundance. This review comprehensively examines recent breakthroughs in magnesium, zinc, aluminum, and calcium-based battery chemistries, with a focus on overcoming barriers related to slow ion transport, limited reversibility, and electrode degradation. Advances in aqueous and non-aqueous electrolyte formulations, including solvation shell engineering, interfacial passivation, and dual-zone ion transport, are discussed for their role in improving compatibility and cycling stability. Particular focus is placed on three high-impact innovations: solvation-optimized Mg-ion systems for improved mobility and retention, interface-engineered Zn-ion batteries enabling dendrite-free operation, and sustainable Al-ion technologies targeting grid-scale deployment with eco-friendly electrolytes and recyclable materials. Cross-cutting insights from operando characterization techniques and AI-guided materials discovery are also evaluated for their role in accelerating MVIB development. By integrating fundamental materials innovation with practical system design, multivalent ion batteries offer a compelling path toward next-generation, safer, and more sustainable energy storage platforms. Full article

Nanomaterial-based systems (NBS) have emerged as transformative elements in advanced surface engineering, offering superior corrosion resistance, mechanical strength, and tribological resilience governed by unique phenomena inherent to the nanoscale. However, bridging the knowledge gap between these enhanced physicochemical properties and the metrological tools required to quantify them remains a critical challenge. This review provides a comprehensive examination of the fundamental mechanisms, state-of-the-art experimental techniques, and computational strategies employed to probe NBS behavior. The article first elucidates the core mechanisms driving performance, including passive barrier formation, stimuli-responsive active corrosion inhibition, grain boundary strengthening, and the formation of protective tribo-films by 2D nanomaterial-based systems. Subsequently, the article evaluates the transition from conventional macroscopic testing to high-resolution in situ characterization, highlighting the capabilities of High-Speed Atomic Force Microscopy (HS-AFM), Liquid Cell Transmission Electron Microscopy (LC-TEM), and nanoindentation in visualizing dynamic defect evolution and measuring localized mechanical responses. Furthermore, the indispensable role of computational materials science—specifically Molecular Dynamics (MD) and Machine Learning (ML)—in predictive modeling and elucidating atomic-scale interactions is discussed. Finally, persistent challenges regarding substrate interference, sample heterogeneity, and instrumentation limits are addressed, concluding with a perspective on future research directions focused on standardization, operando testing, and the development of AI-driven “Digital Twins” for accelerated testing and material optimization. Full article