A Z‐Scheme‐Inspired Photobioelectrochemical H₂O/O₂ Cell with a 1 V Open‐Circuit Voltage Combining Photosystem II and PbS Quantum Dots

Abstract

A biohybrid photobioanode mimicking the Z‐scheme has been developed by functional integration of photosystem II (PSII) and PbS quantum dots (QDs) within an inverse opal TiO2 architecture giving rise to a rather negative water oxidation potential of about −0.55 V vs. Ag/AgCl, 1 m KCl at neutral pH. The electrical linkage between both light‐sensitive entities has been established through an Os‐complex‐modified redox polymer (POs), which allows the formation of a multi‐step electron‐transfer chain under illumination starting with the photo‐activated water oxidation at PSII followed by an electron transfer from PSII through POs to the photo‐excited QDs and finally to the TiO2 electrode. The photobioanode was coupled to a novel, transparent, inverse‐opal ATO cathode modified with an O2‐reducing bilirubin oxidase for the construction of a H2O/O2 photobioelectrochemical cell reaching a high open‐circuit voltage of about 1 V under illumination.

Production of photocurrent and hydrogen gas from intact plant leaves

“…Intact photosynthetic microorganisms, organelles such as chloroplasts 30 , thylakoid membranes 31 or isolated photosynthetic complexes such as Photosystem II (PSII) [32][33][34] or Photosystem I (PSI) [34][35][36][37][38][39][40] have been coupled with electrodes in different bio-photo electrochemical cells configurations. Upon illumination, these photosynthetic components are able to convert absorbed light energy into electrical current collected by the anode.…”

Quantum Dots Assembled with Photosynthetic Antennae on a Carbon Nanotube Platform: A Nanohybrid for the Enhancement of Light Energy Harvesting

“…Photosynthetic proteins are often considered a part of nanobiodevices, working as biosensors or alternative energy sources . In one of the noteworthy examples, Z-scheme mimics were constructed using a photoanode of photosystem II-PbS quantum dots assembled on a TiO 2 electrode . In this approach, a bilirubin oxidized modified opal-ATO plate served as a cathode.…”

Scalable Three-Dimensional Photobioelectrodes Made of Reduced Graphene Oxide Combined with Photosystem I

“…28,29 It has been entrapped in poly-benzylviologen or polyaniline for wired electron transfer. 30,31 Mediated electron transfer was achieved via redox polymers, 12,16 small redox molecules, 32,33 and different cytochromes. 9,34,35 In recent years, significant efforts have been devoted to increasing the efficiency of photobioelectrodes based on PSI.…”

“…Humanity can utilize the competence of nature for sunlight conversion in biohybrid photovoltaic devices. In these systems, artificial electrode materials are combined with photoactive protein complexes, like PSI, − PSII, − or bacterial reaction centers. − Alternatively, thylakoid membranes − or whole cells − are used for biohybrid electric current production. In a more advanced step, additionally, the production of valuable chemicals is implemented. , Furthermore, biophotovoltaics, as photobioelectrodes are called alternatively, can optionally be used as photobiosensors. , …”

“…In biophotovoltaics, successful examples for these electron transfer mechanisms can be found in the literature. PSI has been connected directly to graphene. , It has been entrapped in poly-benzylviologen or polyaniline for wired electron transfer. , Mediated electron transfer was achieved via redox polymers, , small redox molecules, , and different cytochromes. ,, …”