Integration of Photosystem I with Graphene Oxide for Photocurrent Enhancement

Abstract

matrixes, [ 5 ] the use of thick protein fi lms, [ 9 ] and the use of semiconductor electrode materials. [ 10,11 ] The integration of PSI with carbon nano-materials, however, has been limited. The work of Carmeli and co-workers demonstrated how PSI could be covalently attached to carbon nanotubes. [ 12 ] Additionally, our research group demonstrated how PSI could be interfaced as a monolayer on a graphene electrode. [ 13 ] The use of carbon nanostructures such as graphene and carbon nanotubes to develop nano-composite materials has become an area of great research interest due to the unique properties of these materials. [ 14 ] The time-consuming and challenging preparation of graphene, however, has resulted in the increased interest in graphene oxide (GO). [ 15 ] GO, the oxidized form of graphene, is easily generated through the oxidation and subsequent exfoliation of graphite. The oxygen functional groups enable GO to be dispersed in polar solvents (i.e., water) and further functionalized. However, because the conjugation of the system is disrupted, the conductivity of GO is fi ve orders of magnitude lower than graphite. [ 16 ] To regain conductivity, GO is commonly reduced to generate reduced graphene oxide (RGO). [ 17 ] Both GO and RGO have been incorporated with various materials to develop new functional composites. [ 18,19 ] The addition of GO and RGO is particularly attractive for PSIbased devises for a number of reasons. GO and RGO are both water-soluble, making the integration of these materials with PSI straightforward. Furthermore, the low cost and facile synthesis of GO and RGO make these materials ideal candidates for making inexpensive composite materials. The functional groups present on GO make possible the interaction with both the polar groups of PSI as well as the electrochemical mediator. However, the improved conductivity of RGO can facilitate electron transfer between the PSI complexes and the underlying electrode. Here we describe how incorporating either GO or RGO with PSI can improve the photoelectrochemical properties of p-doped silicon. Experimental SectionExtraction and Isolation of Photosystem I : Photosystem I complexes were isolated from commercially available baby spinach leaves as described previously. [ 11 ] Briefl y, the baby spinach was Photosystem I is a photoactive membrane protein used in nature to photoexcite electrons with nearly unit internal quantum effi ciency, sparking interest in using this biomaterial for solar energy conversion. Films of PSI deposited on p-doped silicon have previously demonstrated signifi cant photocurrents with an electrochemical mediator; however, improvement in electron transfer is needed. Here, it is investigated how PSI can be combined with graphene oxide (GO) or reduced graphene oxide (RGO) to generate composite fi lms capable of improved photoelectrochemical performance. It is found that both composite fi lms outperformed the PSI fi lm alone, and the PSI-GO composite fi lm is found to perform the best. The enhancement is attributed to the d...

Dependence of the energy transfer to graphene on the excitation energy

“…Taken together, these observations strongly suggest that the energy absorbed by PCP complexes, both at 405 nm and 640 nm, after being transferred between and within the pigments comprising the light-harvesting complex, is efficiently dissipated into the graphene layer. In general such effects can also be attributed to electron transfer from photosynthetic complex to graphene, as observed recently in [25]. However in this case a charge-separating complex, that is Photosystem I, was used and the whole structure was immersed in properly chosen electrolyte in order to facilitate the electron transfer.…”

Rational Design of Photo-Electrochemical Hybrid Devices Based on Graphene and Chlamydomonas reinhardtii Light-Harvesting Proteins

“…4c), which could be attributed to the basal activity of electrodes. In this regard, it has been recently shown that graphene display photocurrent in isolation 45,46 . Basal photocurrent also varied according to the electrolyte composition within the microampere range ( Fig.…”

Silver Island Film for Enhancing Light Harvesting in Natural Photosynthetic Proteins

“…There are several promising concepts related to using different materials, which can act as transparent conducting electrodes, like graphene, TiO 2 or ITO [63,[69][70][71][72], and different complexes that perform light-harvesting, charge separation and charge transfer [4,8,9,16,28,29,73]. At the same time, plasmonic nanomaterials, like SIFs or nanowires, seem to be excellent structures for improving the performance of photosynthetic materials, not only in terms of enhancing the optical properties, but also their charge transfer properties, leading to increased photocurrent generation.…”