Hydrogen-Bonding Primary and Secondary Coordination Sphere Effects on Water Oxidation Catalyzed by Transition Metal Complexes

Rising energy needs, the threat of climate change, and the diminishing reserves of non-renewable energy underscore the urgency for advancing alternative, sustainable, clean energy sources. Hydrogen is currently appraised as a logical, sustainable power source, with electrochemical water splitting emerging as a critical method for its production. Water oxidation, a key step in artificial photosynthesis, remains a significant challenge in the development of sustainable energy systems. Transition metal complexes have emerged as promising catalysts for this reaction due to their tunable structures and remarkable catalytic properties. Among the various factors influencing their performance, hydrogen bonding has gained increasing attention as a critical element in shaping catalytic efficiency and reaction pathways. The review explores the multifaceted role of hydrogen bonding in transition metal-based water oxidation catalysts, highlighting its impact on structural stability, proton transfer dynamics, and electronic modulation of active sites. We discuss recent advancements in understanding how hydrogen-bonding interactions influence catalytic activity and selectivity, drawing on both experimental findings and computational insights. By shedding light on the pivotal role of hydrogen bonding, this review aims to inspire innovative approaches for designing next-generation catalysts for sustainable water-splitting technologies.