Unveiling a Tetrahedrally Coordinated Cobalt-Nucleotide Hydrogel as an Efficient Bifunctional Electrocatalyst for...

Amid the global drive to eliminate carbon emissions and to mitigate the energy crisis, water splitting emerges as a beacon of innovation, converting water into clean hydrogen and oxygen. Most electrocatalysts for water splitting rely on precious metals, highlighting the demand for cost-effective, efficient, and reproducible alternatives. Herein, we report the development of a cobalt-adenosine monophosphate (CAH) hydrogel as a bifunctional catalyst for overall water splitting in alkaline conditions with a cell voltage of 1.56 V at 10 mA cm^-2, outperforming the benchmark catalytic system IrO₂||Pt/C (1.62 V at 10 mA cm^-2). Three crucial factors contributed to the notable water splitting of this hydrogel: (i) phosphate group in the AMP coordinated with central Co²⁺ ions, promoting effective adsorption of key intermediates, (ii) tetrahedral arrangement around cobalt atoms making the active site more exposed and accessible, enabling better interaction with reactants and intermediates, (iii) the formation of hydrogel enhances electrolyte confinement, thus accelerating reaction kinetics. At elevated temperature, the hydrogel achieves a low cell voltage of 1.42 V at 1.0 M KOH. Even under industrially relevant harsh conditions, the hydrogel achieves 10 mA cm^-2 at 1.53 V, underscoring its durability. This simple nucleotide-based coordination polymer might bring significant advancement in sustainable energy conversion.