TRANSITION METAL NANOSTRUCTURED CATALYSTS FOR ENERGY CONVERSION AND STORAGE APPLICATIONS: A COMPREHENSIVE REVIEW

Abstract

The global energy landscape is undergoing a significant transition due to increasing concerns over fossil fuel depletion, rising energy demands, and environmental pollution [27,28,36]. In this scenario, the development of efficient and sustainable energy conversion and storage systems has become a major scientific priority [29,36]. Among the various materials investigated, transition metal nanostructured catalysts have attracted considerable attention owing to their unique physicochemical properties and broad application potential [32,34,38]. These materials, particularly based on Fe, Co, Ni, Mn, and Cu and their corresponding compounds such as oxides, sulfides, phosphides, and carbides, offer a cost-effective alternative to noble metal catalysts [32,38]. Their nanoscale dimensions provide a high density of active sites, improved electron transfer behavior, and tunable surface chemistry, all of which directly influence catalytic performance [30,38]. In electrochemical energy systems, these catalysts play a central role in key reactions such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) [4–6,10,19]. These reactions are fundamental to technologies like water electrolysis, fuel cells, and metal–air batteries. In parallel, transition metal nanostructures have also shown promising results in energy storage devices, including lithium-ion batteries, sodium-ion batteries, and supercapacitors, where they enhance capacity, rate performance, and cycling stability [23,24,27]. Despite these advantages, several challenges still limit their large-scale application. Issues such as structural instability under operating conditions, particle agglomeration, and insufficient long-term durability remain critical concerns [30,31]. Recent research has therefore focused on improving material design through strategies such as heterostructure formation, doping, defect engineering, and development of single-atom catalysts [30,31,38].

Overall, transition metal nanostructured catalysts represent a rapidly evolving research area that bridges fundamental materials chemistry with practical energy technologies, offering promising pathways toward sustainable energy systems [32,34].