Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting

Abstract

In natural photosynthesis, light is used for the production of chemical energy carriers to fuel biological activity. The re-engineering of natural photosynthetic pathways can provide inspiration for sustainable fuel production and insights for understanding the process itself. Here, we employ a semiartificial approach to study photobiological water splitting via a pathway unavailable to nature: the direct coupling of the water oxidation enzyme, photosystem II, to the H2 evolving enzyme, hydrogenase. Essential to this approach is the integration of the isolated enzymes into the artificial circuit of a photoelectrochemical cell. We therefore developed a tailor-made hierarchically structured indium-tin oxide electrode that gives rise to the excellent integration of both photosystem II and hydrogenase for performing the anodic and cathodic half-reactions, respectively. When connected together with the aid of an applied bias, the semiartificial cell demonstrated quantitative electron flow from photosystem II to the hydrogenase with the production of H2 and O2 being in the expected two-to-one ratio and a light-to-hydrogen conversion efficiency of 5.4% under low-intensity red-light irradiation. We thereby demonstrate efficient light-driven water splitting using a pathway inaccessible to biology and report on a widely applicable in vitro platform for the controlled coupling of enzymatic redox processes to meaningfully study photocatalytic reactions.

Solar Water Splitting with a Hydrogenase Integrated in Photoelectrochemical Tandem Cells

“…A two‐electrode PEC cell consisting of the FTO|IO‐ITO|PSII photoanode coupled to the Si|IO‐TiO 2 |H 2 ase photocathode was irradiated with UV‐filtered simulated solar light (100 mW cm −2 ; AM1.5G; IR water filter; λ >420 nm; 25 °C) for 3 h at U =0.4 V, which resulted in the generation of 0.70±0.13 μmol cm −2 of H 2 with a Faradaic efficiency of (91±19) % (Figure 4 B). This semi‐artificial tandem PEC cell therefore allows for a wider usage of the solar spectrum at a reduced voltage than the previously reported3a single‐light‐absorber system. …”

“…A hierarchically structured IO‐TiO 2 layer of 10 μm film thickness was subsequently assembled on top of the ALD layer by co‐assembly of TiO 2 nanoparticles (P25, 21 nm) with polystyrene beads (750 nm), followed by heating at 450 °C 3a. Characterization by scanning electron microscopy (SEM; Figures 1 A and S4) showed a macropore diameter of 750 nm, facilitating the penetration of large biomolecules.…”

“…H 2 ase had previously been wired to PSII in a PEC configuration, but both enzymes were immobilized on hierarchical IO‐ITO electrodes 3a. The single light‐absorbing PEC cell contained a “dark” IO‐ITO|H 2 ase cathode, which resulted in the requirement of a large external voltage ( U >0.6 V) to achieve overall water splitting.…”

Photoelectrochemical H2 Evolution with a Hydrogenase Immobilized on a TiO2‐Protected Silicon Electrode

“…As such, we were able to demonstrate quantitative water splitting and the net storage of light energy as H 2 using this hydrogenase, wired to a photosystem II‐based photoanode, in a photoelectrochemical cell 9. However, this system relies on the hydrogenase being adsorbed onto a hierarchical indium–tin oxide electrode, which requires an applied bias to perform proton reduction 9.…”

Studi Dinamika Molekular dan Kinetika Reaksi pada Pembelahan Molekul Air untuk Produksi Gas Hidrogen

“…Modifikasi nanostruktural sangat penting dilakukan untuk mendapatkan kondisi efektif dalam proses pembelahan air menjadi hydrogen dan oksigen. Mersch et al (2015) melaporkan modifikasi yang berkaitan evolusi gas Hidrogen dan gas Oksigieen pada elektroda dengan bantuan enzim (5) dan microba (6). Sementara, mekanisme reaksi pada permukaan elektroda juga telah dibahas oleh Pfeifer et al (2016), tentang bagaimana evolusi gas Oksigen dari Anoda (7; 8).…”