Photobio-electrocatalytic production of H2 using fluorine-doped tin oxide (FTO) electrodes covered with a NiO-In2S3 p-n junction and NiFeSe hydrogenase.

Clean energy vectors are needed towards a fossil fuel-free society, diminishing both greenhouse effect and pollution. Electrochemical water splitting is a clean route to obtain green hydrogen, the cleanest fuel; although efficient electrocatalysts are required to avoid high overpotentials in this process. The combination of inorganic semiconductors with biocatalysts for photoelectrochemical H2 production is an alternative approach to overcome this challenge. N-type semiconductors can be coupled to a co-catalyst for H2 production in the presence of a sacrificial electron donor in solution, but the replacement of the latter with an electrode is a challenge. In this work we attach a NiFeSe-hydrogenase with high activity for H2 production with the n-type semiconductor indium sulfide, which upon visible irradiation is able to transfer its excited electrons to the enzyme. In order to enhance the transfer of the generated holes towards the electrode for their replenishment, we have explored the inclusion of a p-type material, NiO, to induce a p-n junction for H2 production in a photoelectrochemical biocatalytic system in absence of sacrificial reagents.

Enhancement of Biosensors by Implementing Photoelectrochemical Processes.

Research on biosensors is growing in relevance, taking benefit from groundbreaking knowledge that allows for new biosensing strategies. Electrochemical biosensors can benefit from research on semiconducting materials for energy applications. This research seeks the optimization of the semiconductor-electrode interfaces including light-harvesting materials, among other improvements. Once that knowledge is acquired, it can be implemented with biological recognition elements, which are able to transfer a chemical signal to the photoelectrochemical system, yielding photo-biosensors. This has been a matter of research as it allows both a superior suppression of background electrochemical signals and the switching ON and OFF upon illumination. Effective electrode-semiconductor interfaces and their coupling with biorecognition units are reviewed in this work.