Hydrogen energy plants, comprising of water electrolyzers, fuel cells, compressors, storage systems, and associated Balance of Plant components, represent a central pillar of the emerging green energy transition. Among the available hydrogen production pathways, green hydrogen produced via water electrolysis powered by renewable electricity is the most carbon-free route, and its efficient production and valorization through fuel cells necessitates a thorough understanding of the underlying electrochemical reactions and coupled physical processes. This mini-review summarizes fundamental process parameters, multiscale modeling strategies, and state-of-the-art digital twin integration frameworks across hydrogen production and utilization technologies. The interconnected physical phenomena of reaction reversibility, membrane ionic transport, catalyst and membrane degradation mechanisms, and heat and mass transfer are discussed as the essential governing equations that a faithful digital twin must encode. Furthermore, the multiscale modeling approaches applicable to these systems are reviewed across three hierarchical levels followed by discussion on cross-coupling and concepts of ROM/PINN integration along with CPS.
The dual imperatives of carbon-neutral chemical manufacturing and advanced wastewater remediation require high-performance electrocatalysts capable of orchestrating complex, multi-electron reactions. However, pristine catalyst lattices are fundamentally bottlenecked by linear scaling relations. This critical review establishes defect engineering as the definitive strategy for bypassing these thermodynamic limitations, offering a unified mechanistic framework that bridges sustainable energy conversion and environmental remediation. Moving beyond empirical material catalogues, this work systematically interrogates how localized structural imperfections—vacancies, dopants, and synergistic interfaces—act as precision atomic-scale electronic regulators. By modulating the transition-metal d-band center and triggering spatial charge redistribution, defects successfully decouple intermediate binding energies to steer reaction pathways thermodynamically. A comprehensive analysis elucidates the electronic origins of defect-mediated performance across green ammonia synthesis (nitrogen and nitrate reduction) and advanced wastewater treatment (electro-Fenton, targeted non-radical persulfate activation, and priority pollutant electroreduction). Furthermore, this review challenges the pervasive assumption of static active sites, emphasizing how operando interrogation reveals the highly dynamic, transient nature of defect architectures under applied electrochemical bias. Finally, the frontier of artificial intelligence-guided discovery and multi-defect synergy is highlighted, charting a translational roadmap from atomic-level precision to robust industrial reactor integration. Ultimately, this review elevates defect electrocatalysis from a purely descriptive phenomenon into a predictive, quantitatively guided design discipline essential for achieving closed-loop global sustainability.
Renewable electricity-driven water electrolysis offers a promising route to low-emission hydrogen, yet exceptional laboratory catalyst performance does not necessarily translate into efficient, durable, and scalable electrolyzer operation. This review examines nanostructured electrocatalysts across interconnected length scales, linking atomic-level electronic structure and adsorption energetics with the potential dependent active phase, electrode transport processes, and complete device integration. Noble metal catalysts, nickel–molybdenum systems, molybdenum disulfide, nickel–iron oxyhydroxides, reconstructing precatalysts, atomically dispersed sites, and compositionally complex materials are critically assessed according to the evidence needed to identify active sites and validate long-term stability. Particular attention is given to alkaline water electrolysis, proton-exchange membrane water electrolysis, anion-exchange membrane water electrolysis, oxygen ion solid oxide electrolysis, and proton-conducting ceramic electrolysis. The review shows that apparent activity can be overstated by surface roughness, transient reconstruction, electrolyte purity, or low catalyst loading, while practical deployment is limited by catalyst layer uniformity, membrane compatibility, ion transport, water supply, gas removal, dissolution, thermal management, dynamic loading, and manufacturing constraints. A unified translation framework is proposed to distinguish mechanistic promise from device-relevant progress and guide the development of efficient, durable, resource-conscious, and verifiably low-emission hydrogen production at scale.
The efficient and simultaneously selective conversion of methane to methanol has been one of the most research-intensive topics in catalysis over the past decades. The weaker C-H bond of methanol promotes the production of over-oxidized species. The present computational study examines the catalytic performance of organometallic complexes with electron rich Earth abundant metals (cobalt, nickel, copper, formally negatively charged). A deliberately designed ligand is proposed to secure the negative charge on the metal and enable the formation of stable terminal metal-oxygen bonds. The ligand coordinates the metal with metal-carbon bonds, and the skeleton of the ligand is chosen to constrain the motion of the coordinated carbon atoms, avoiding the insertion of oxygen to the metal-carbon bond. We found that the energy barriers for methane activation are less than 15 kcal/mol across all three metals, and that the turnover frequency is determined by the methanol-release step, which is highly temperature-sensitive. Therefore, solvent effects and temperature can be tuned to improve the overall catalytic efficiency. The most impressive result of our study is that the activation barriers for methane and methanol are competitive (within 1–2 kcal/mol). This observation makes catalysts with electron rich metal centers unique and promising for efficient and selective conversion of methane to methanol.
The escalating demand for sustainable energy sources and chemical feedstocks has intensified research efforts toward the catalytic conversion of lignocellulosic biomass into value-added products. This comprehensive review critically examines recent advances in metal-based catalytic systems for biomass valorization, encompassing noble metals, transition metals, and their alloys. We systematically analyze the fundamental mechanisms governing catalytic transformations of cellulose, hemicellulose, and lignin, with particular emphasis on structure-activity relationships and catalyst design principles. The review addresses critical challenges including catalyst deactivation, selectivity control, and scalability, while highlighting emerging opportunities in single-atom catalysis, bimetallic synergies, and integrated biorefinery concepts. Furthermore, we discuss the role of advanced characterization techniques and computational approaches in accelerating catalyst discovery. This work provides a roadmap for future research directions aimed at achieving economically viable and environmentally sustainable biomass conversion technologies.
