Designed Metalloprotein-DrivenElectrolyzer Operationalin Seawater

The quest for sustainable energy sources has notably shifted toward green hydrogen production, given its potential to establish a carbon-neutral energy infrastructure. This study introduces a bioinspired catalyst design rationale that precisely integrates a synthetic hydrogen-producing cobaloxime core into a robust azurin protein scaffold to harness the unique interplay between the transition metal active site and the protein-based outer coordination sphere. The appropriate formation of this cobaloxime-azurin construct <b>[2]</b> was studied via spectroscopic techniques to reveal that the cobalt core and the native copper center were electronically decoupled, but both were present in the protein template. The artificial metalloprotein <b>[2]</b> displayed a substantial enhancement in the electrocatalytic H₂ proficiency compared to the precursor cobaloxime molecule in near-neutral aqueous media under aerobic conditions. <b>[2]</b> reached a maximum turnover number of 4.89 × 10⁵ at an overpotential of 0.45 V at pH 6.0 upon direct covalent binding to the electrode surface. The explicit influence of a copper center located in the proximity of the cobaloxime site was validated from the electrochemical studies of control metalloproteins and variable catalyst positioning. The oxygen-tolerant and well-studied metalloprotein <b>[2]</b> was further deployed as a cathodic material along with an oxygen-evolving RuO₂ anode to fabricate an operational electrolyzer that consistently produced hydrogen from pure distilled water (Cell Voltage 2.90 V, output current density 3.0 mA/cm²) to 1:1 distilled water/seawater blend (Cell Voltage 2.65 V, output current density 1.5 mA/cm²). Hence, this study accentuates the importance of adopting a systematic expansion of the bioinspired catalyst design strategy for unfolding an all-weather-ready electrocatalyst for green hydrogen production.