Two-Dimensional Materials as Emerging Electrocatalysts for HER, ORR, and OER: Design Strategies, Challenges, and Prospects in Sustainable Energy Conversion

Abstract

Two-dimensional (2D) materials have emerged as a versatile platform for high-performance electrocatalysts in sustainable energy conversion and storage technologies, including fuel cells, water splitting, and metal-air batteries (MABs). Central part of the electrochemical reactions such as H 2 evolution reaction (HER), O 2 reduction reaction (ORR), and O 2 evolution reaction (OER) determines the efficiency, performances and stability of these systems. While noble metals like Pt, Ir, and Ru exhibit superior activity, their high cost and limited durability hinder large-scale applications. 2D materials, including transition metal dichalcogenides, MXenes, doped graphene, and single-atom 2D catalysts, offer tunable electronic structures, high surface area, abundant active sites, and defect-rich architectures, enabling efficient and durable catalysis. Combined with advanced computational approaches, such as density functional theory (DFT) and machine learning, these materials provide a pathway for rational design and high-throughput screening of next-generation electrocatalysts. This review critically summarizes recent progress in 2D materialbased electrocatalysts for HER, ORR, and OER, highlighting design strategies, synthesis 2 techniques, stability challenges, and emerging trends toward scalable and practical energy conversion technologies.MXenes, carbon-based hybrids, single-atom catalysts, and heteroatom-doped nanostructures as next-generation electrocatalysts. 26,27 Their unique physicochemical properties, including high specific surface area, tunable electronic structure, abundant active sites, and defect-rich surfaces, offer promising avenues for overcoming the performance limitations of traditional catalysts. 25,28 Furthermore, advances in computational modelling, particularly density functional theory (DFT) calculations combined with machine learning (ML) algorithms, are revolutionizing catalyst discovery by enabling high-throughput screening, predictive modeling of activity descriptors, and accelerated rational design of novel electrocatalytic materials. 11,13,29,30 Despite these advances, several key challenges remain: ensuring long-term catalyst stability under operating conditions, achieving scalability in synthesis, understanding degradation mechanisms, and establishing structure-activity relationships at the atomic level. 31,32 This review aims to provide a comprehensive and critical overview of recent progress in electrocatalyst development with an emphasis on multifunctional materials for HER, OER, and ORR. We will discuss fundamental reaction mechanisms, material design strategies, synthetic routes, characterization tools, performance evaluation metrics, current progress, and limitations that are expected to define the next decade of electrocatalysis research.