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

Abstract

Photobioelectrodes represent one of the examples where artificial materials are combined with biological entities to undertake semi-artificial photosynthesis. Here, an approach is described that uses reduced graphene oxide (rGO) as an electrode material. This classical 2D material is used to construct a three-dimensional structure by a template-based approach combined with a simple spin-coating process during preparation. Inspired by this novel material and photosystem I (PSI), a biophotovoltaic electrode is being designed and investigated. Both direct electron transfer to PSI and mediated electron transfer via cytochrome c from horse heart as redox protein can be confirmed. Electrode preparation and protein immobilization have been optimized. The performance can be upscaled by adjusting the thickness of the 3D electrode using different numbers of spin-coating steps during preparation. Thus, photocurrents up to ∼14 μA/cm2 are measured for 12 spin-coated layers of rGO corresponding to a turnover frequency of 30 e– PSI–1 s–1 and external quantum efficiency (EQE) of 0.07% at a thickness of about 15 μm. Operational stability has been analyzed for several days. Particularly, the performance at low illumination intensities is very promising (1.39 μA/cm2 at 0.1 mW/cm2 and −0.15 V vs Ag/AgCl; EQE 6.8%).

Development of a Novel Nanoarchitecture of the Robust Photosystem I from a Volcanic Microalga Cyanidioschyzon merolae on Single Layer Graphene for Improved Photocurrent Generation

“…These data clearly point towards the beneficial role of the PSI biolayer on improving the stability of photocurrent generation in SLG. Overall, the systems described in this work generated 2-7-fold higher photocurrent densities compared to those obtained for the PSI-based devices constructed with various types of electrode material, including planar gold [51], 3D reduced graphene oxide [52] or SLG [38]. On the other hand, the biohybrid system based on PSI conjugated with nitrogendoped carbon nanotubes in a wired or non-wired configuration generated the photocurrent density of 625 nA•cm −2 at +0.3 V vs. Ag/AgCl in the presence of an external redox mediator [53], which is lower than for the mediatorless SLG/pyr-NTA-M 2+ /His 6 -PsaD-PSI system reported here (see Table 2).…”

Layer-by-Layer Assembly of Photosystem I and PEDOT:PSS Biohybrid Films for Photocurrent Generation

“…These results agree with recent reports on the importance of dissolved oxygen in PSI bioelectrodes and the use of ubiquinone-0 as an electron acceptor from PSI. 3,49,50,53 In summary, PSI creates an excess of reduced ubiquinone-0 upon illumination and an anodic current is realized when the excess reduced ubiquinone-0 is oxidized at either the PEDOT:PSS interlayers or the electrode surface.…”

Graphene oxide decorated with gold enables efficient biophotovolatic cells incorporating photosystem I

“…[26][27][28][29][30] Nano-composites based on carbon allotropes such as graphene, graphene oxide (GO) and reduced graphene oxide (rGO) exhibit a similar combination of useful properties: high electrical conductivity, large surface area, mechanical exibility, good carrier mobility, thermal conductivity and transparency in the visible range of the spectrum. 7,11,21,[31][32][33] These materials have been used as chargetransfer layers in silicon-based solar cells, [34][35][36] dye-sensitized solar cells [37][38][39] and other energy storage devices. 27,[40][41][42] In previous studies, when PSI was deposited onto GO surfaces, the hydroxy (-OH), carboxylic acid (-COOH), and epoxide groups present in GO make it particularly well suited for PSI-based BPV devices because they interact selectively with PSI to affect the orientation of the hole-and electron-injecting sides with respect to the charge-transfer layers and electrodes.…”

“…1,7 These groups can also be used to tune the electric properties of GO by varying the oxygen quantity of the layers. 43,44 Examples of successful strategies that utilize these properties in PSI-based BPV cells include coupling PSI on graphene electrodes modied with NHS-pyrene (N-hydroxysuccinimid) esters, 17 immobilizing PSI on threedimensional rGO electrodes modied with cytochrome c, 31 directly conjugating PSI to graphene, 7 incorporating oriented PSI in single-layer graphene akes functionalized with Ni 2+ nitrilotriacetic acid chelates (Ni-NTA), cytochrome c 553 , 45 and depositing composite lms of PSI with GO and rGO on p-doped silicon. 46 All of these studies demonstrate signicant progress in the maximizing of photocurrents in BPV devices.…”