Single atom horizons for shaping the future of catalysis and sustainability: the next frontiers in energy conversion and storage

Single-atom catalysts have recently emerged as a revolutionary frontier in catalysis, energy production, and storage. Due to their compositional diversity, structural tunability, and modulated distinctive electronic properties, SACs pave significant promises for viable avenues toward a more sustainable future. Here, the discussion begins with the emergence of SACs, their synthesis techniques to regulate atomic dispersion, atomically-resolved advanced characterizations, probing different supports, and engineering strategies to boost stability and reactivity. This review as a key reference in this field comprises the mechanistic understanding of SACs in electrocatalysis, photocatalysis, and thermocatalysis for energy and environmental applications. We also discussed their transformative potential in H₂ and O₂ evolution reactions for water splitting, the reduction of O₂, carbon dioxide, N₂, and nitrate for electrocatalysis and photocatalysis, and their remarkable role in energy storage technologies, including metal-O₂, lithium-sulfur, and metal-CO₂ batteries. Additionally, we assess their efficiency in environmental remediation by removing harmful nitrogen oxides, various hydrogenation processes, catalytic oxidation, and CO₂ hydrogenation, which sets this review apart from others. Despite the considerable progress, challenges persist in the scalability and commercial implementation of SACs. This comprehensive review significantly delivers valuable insights into the current advancement of SACs, highlighting their substantial potential and suggesting future research avenues that would enable next-generation technologies for energy conversion, storage, environmental sustainability, and various other functional applications.