A precursor-approach in constructing 3D ITO electrodes for the improved performance of photosystem I-cyt c photobioelectrodes

Abstract

A precursor-based approach has been employed for the construction of scalable, transparent 3D photobioelectrodes based on PSI and cyt c. An improved transparancy and high photocurrents can be achieved as compared to nanoparticle-based preparation methods.

Photosystem I Multilayers within Porous Indium Tin Oxide Cathodes Enhance Mediated Electron Transfer

“…The macro‐ITO cathodes achieve a peak cathodic photocurrent of 42.4±5.2 μA cm −2 , the meso‐ITO yield 10.7±0.9 μA cm −2 , and the planar ITO gives 1.1±0.6 μA cm −2 at a PSI loading of 132 mol cm −2 . We also tested porous PSI‐ITO cathodes with pore sizes of 500 nm because similar pore sizes have been shown to be optimal for photocurrent generation by PSI and cyt c . However, the 500 nm pore cathodes produced photocurrent values comparable to the meso‐ITO (Figure S9).…”

“…found that porous ITO electrodes incorporating cyt c as a linking agent show a maximum performance of 270 μA cm −2 at the 460 nm pore size in comparison to macropores up to 3 μm with an applied potential of 200 mV vs. Ag/AgCl. The maximum is attributed to a maximum areal loading of cyt c and PSI on the ITO surface due to a higher protein binding capacity within smaller pores . These reports have shown that porous ITO is an effective cathode material for PSI‐based bioelectrodes in conjunction with cyt c and an applied potential to drive DET.…”

“…PSI‐modified macro‐ITO cathodes were capable of utilizing double the available active surface area, when compared to meso‐ITO cathodes with the same PSI mass loading. Our findings show that if MET alone is considered, 5 μm pores outperformed their mesoporous ITO equivalent, while other studies that report a DET‐based mechanism find that pores on the scale of hundreds of nanometers are optimal . We conclude that this difference in findings is due to the difference between the electron transfer pathways.…”

“…[6][7][8] To enable DET, monolayers of PSI protein complexes have been coupled with various linking molecules and proteins, which help minimize the electrodeprotein separation distance and also provide an energetically favorable pathway for electron transfer. [7,[14][15][16][17][18][19][20][21][22][23][24] Most notably, the cytochrome complex (cyt c) has been used to attach PSI onto a variety of electrode materials. [7,[14][15][16][17][18][19][20][21][22][23][24] Alternatively, significant improvements in mediated photocurrent generation have been achieved by drop-casting thick multilayer films of PSI onto silicon, gold, and graphene electrodes.…”

“…[7,[14][15][16][17][18][19][20][21][22][23][24] Most notably, the cytochrome complex (cyt c) has been used to attach PSI onto a variety of electrode materials. [7,[14][15][16][17][18][19][20][21][22][23][24] Alternatively, significant improvements in mediated photocurrent generation have been achieved by drop-casting thick multilayer films of PSI onto silicon, gold, and graphene electrodes. [5,[25][26][27] Applying thicker films of PSI improves overall light absorption by providing a higher areal protein loading and increasing the total amount of converted mediator.…”