The global transition toward low‐carbon energy systems is constrained by the carbon intensity and scalability limitations of current hydrogen production technologies. Although hydrogen is widely recognized as a clean energy carrier, the absence of an integrated and comparative framework limits its system‐level optimization. This review presents a critical assessment of hydrogen production technologies encompassing industrial processes, biomass, and electrochemical pathways. Conventional processes are analyzed across decarbonization strategies, while biomass‐derived electrochemical pathways are evaluated for feedstock flexibility and life‐cycle emission advantages. Advanced technologies, including thermochemical water‐splitting cycles, plasma‐assisted reforming, solar‐driven thermochemical processes, photocatalytic and biological routes, are critically examined with respect to scalability, materials limitations, and system integration challenges.
Chalcogen‐containing coumarins have attracted considerable attention as a versatile class of heterocyclic compounds because sulfur‐ and selenium‐substituted derivatives can significantly influence molecular reactivity, electronic characteristics, and biological activity. Over the past decades, synthetic approaches toward these compounds have advanced through two main strategies: direct construction of the coumarin framework through cyclization processes and late‐stage functionalization of preformed coumarin scaffolds. This review provides a comprehensive survey of the methodologies reported over the past two decades for the preparation of chalcogen‐substituted coumarins, with particular emphasis on derivatives functionalized at the C‐3 and C‐4 positions. Special attention is given to substrate scope, regioselectivity, mechanistic insights, and the use of modern enabling technologies as well as a literature‐based quantitative analysis.
Nucleic‐acid biomarkers play pivotal roles in disease diagnosis, therapeutic monitoring, and precision medicine, creating an urgent demand for analytical platforms combining high sensitivity, molecular specificity, and rapid detection. Surface‐enhanced Raman spectroscopy (SERS) integrated with aptamers, short single‐stranded DNA or RNA oligonucleotides, has attracted considerable attention by coupling programmable molecular recognition with ultrasensitive plasmon‐enhanced Raman detection. This review evaluates recent advances in aptamer‐based SERS biosensors for nucleic‐acid analysis, systematically examining sensing mechanisms, plasmonic substrate engineering, aptamer immobilization, signal‐transduction pathways, and amplification approaches, including catalytic hairpin assembly, hybridization chain reaction, rolling circle amplification, and CRISPR‐assisted systems. Recent developments in microfluidics, artificial intelligence‐assisted spectral analysis, portable Raman instrumentation, and point‐of‐care platforms are assessed while distinguishing true aptamer‐mediated sensing from conventional hybridization‐based DNA detection. Rational hotspot engineering, deterministic nanogap architectures, and advanced amplification strategies have enabled detection from femtomolar to attomolar levels with improved selectivity, multiplexing, and reproducibility. Challenges including substrate variability, quantitative standardization, aptamer stability, biosafety, and clinical translation are discussed. Future directions toward standardized, intelligent, clinically deployable SERS platforms for next‐generation molecular diagnostics and precision healthcare are proposed.
Picophotonics describes light–matter interactions in which atomic‐scale structure, sub‐nanometer confinement, or picometer‐scale structural variations significantly influence optical response. This review establishes a unified framework for understanding these interactions across plasmonic picocavities, molecular systems, and van der Waals (vdW) materials and heterostructures. We examine key mechanisms governing extreme optical confinement, including nonlocality, electron tunneling, charge–transfer effects, excitonic interactions, and phonon/plasmon polaritons. Experimental approaches, including scanning tunneling microscopy‐based optical measurements, tip‐enhanced Raman spectroscopy, near‐field optical microscopy, and ultrafast spectroscopy, are discussed together with electromagnetic and quantum‐mechanical modeling methods. Particular emphasis is placed on how atomic‐scale structural variations, interfacial geometry, and material composition regulate optical response and enable applications in single‐molecule spectroscopy, chemical sensing, cavity‐modified chemistry, and quantum photonics. We further compare metallic picocavities with vdW polaritonic and hybrid plasmonic–vdW platforms in terms of confinement, losses, tunability, reproducibility, and scalability. Finally, key challenges involving experimental artifacts, heating, fabrication, and quantitative metrology are critically assessed, providing perspectives toward reproducible and programmable picoscale light–matter interactions.
Polyoxometalates (POM) are one of the areas of inorganic chemistry that is actively developing due to the broad application of POM‐based materials in the emerging areas of modern science and technology. POMs are a huge family of oxocomplexes distinguished by specific intrinsic properties dependent on the size, structure, and charge. The key role in the performance of POM anions is the ability to generate various interactions with a huge number of species (both charged and neutral). This review is focused on the analysis of the modern trends in the most excited type of bonds—noncovalent interactions—their structural characteristics, and the application in the design of advanced materials.
