Electrostatic [FeFe]-Hydrogenase–Carbon Nitride Assemblies for Efficient Solar Hydrogen Production

The assembly of semiconductors as light absorbers and enzymes as redox catalysts offers a promising approach for sustainable chemical synthesis driven by light. However, achieving the rational design of such semi-artificial systems requires a comprehensive understanding of the abiotic-biotic interface, which poses significant challenges. In this study, we demonstrate an electrostatic interaction strategy to interface negatively charged cyanamide modified graphitic carbon nitride (NCNCNX) with an [FeFe]-hydrogenase possessing a positive surface charge around the distal FeS cluster responsible for electron uptake into the enzyme. The strong electrostatic attraction enables efficient solar hydrogen (H2) production via direct interfacial electron transfer (DET), achieving a turnover frequency (TOF) of 18,669 h–1 (4 h) and a turnover number (TON) of 198,125 (24 h). Interfacial characterizations, including quartz crystal microbalance (QCM) and photoelectrochemical impedance spectroscopy (PEIS), have been conducted for the first time on a carbon nitride-enzyme to provide a comprehensive understanding for the future development of photocatalytic hybrid assemblies.