Exploring Recent Progress in First-Row Trimetallic Nanostructures and Their Derivatives for Electrocatalytic Water Splitting: A Comprehensive Review

Present scientific efforts are heavily concentrated on enhancing energy storage and conversion technologies to reduce environmental degradation and tackle impending energy issues. Electrocatalytic water splitting emerges as a leading method for producing pure hydrogen without generating undesired byproducts, highlighting the need for robust, cost-effective, highly active, and earth-abundant electrocatalyst materials composed of non-noble metals that exhibit excellent stability and performance for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at low overpotentials and high efficiencies. In this context, the design and engineering of trimetallic nanostructured materials with diverse architectures emerge as a promising strategy for energy conversion electrocatalysis. These trimetallic nanostructures, particularly those incorporating first-row transition metals, exhibit distinctive physicochemical properties, heightened efficacy, and enhanced durability across diverse applications compared to mono- and bimetallic counterparts, driven by synergistic interactions among the trimetals. Moreover, the incorporation of additional metals into the secondary building units (SBUs) of frameworks represents an efficacious strategy for augmenting electrochemical performance and electrical conductivity, increasing active site exposure, enhanced charge capacity, and proficient charge transfer among distinct ions. In this review, fundamental concepts and key evaluation metrics for electrochemical water-splitting reactions are outlined. Subsequently, an overview of recent advancements in the synthesis, structural/chemical modifications, and utilization of first-row transition metals as multifunctional nanomaterials for overall water splitting is elucidated. Then, a comprehensive analysis is provided on various trimetallic catalyst categories based on first-row transition metals, encompassing alloys, oxides, hydroxides, nitrides/phosphides/sulfides, and composite structures, aiming to expand the understanding of trimetallic systems and delineate a roadmap for the integration of diverse trimetallic materials as advanced candidates in electrochemical energy storage and conversion technologies.