Carbon nitride-TiO2 hybrid modified with hydrogenase for visible light driven hydrogen production.

A system consisting of a [NiFeSe]-hydrogenase (H2ase) grafted on the surface of a TiO2 nanoparticle modified with polyheptazine carbon nitride polymer, melon (CN x ) is reported. This semi-biological assembly shows a turnover number (TON) of more than 5.8 × 105 mol H2 (mol H2ase)-1 after 72 h in a sacrificial electron donor solution at pH 6 during solar AM 1.5 G irradiation. An external quantum efficiency up to 4.8% for photon-to-hydrogen conversion was achieved under irradiation with monochromatic light. The CN x -TiO2-H2ase construct was also active under UV-free solar light irradiation (λ > 420 nm), where it showed a substantially higher activity than TiO2-H2ase and CN x -H2ase due, in part, to the formation of a CN x -TiO2 charge transfer complex and highly productive electron transfer to the H2ase. The CN x -TiO2-H2ase system sets a new benchmark for photocatalytic H2 production with a H2ase immobilised on a noble- and toxic-metal free light absorber in terms of visible light utilisation and stability.We acknowledge support by the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and National Foundation for Research, Technology and Development), the OMV Group and a Marie Curie fellowship to C.C. (GAN 624997). R.B. and L.W. acknowledge financial support by the MIWFT‐NRW within the project “Anorganische Nanomaterialien für Anwendungen in der Photokatalyse“. We thank Dr. J. C. Fontecilla-¬Camps and Dr. C. Cavazza (CNRS Grenoble, France) for providing us with Dmb [NiFeSe] hydrogenase, Ms. Marielle Bauzan (CNRS Marseilles, France) for growing the bacteria, and Dr. Michal Bledowski for assistance with CN_X¬‐TiO_2 synthesis.This is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5SC02017