3D-printed hierarchical pillar array electrodes for high-performance semi-artificial photosynthesis

The rewiring of photosynthetic biomachineries to electrodes is a forward-looking semi-artificial route for sustainable bio-electricity and fuel generation. Currently, it is unclear how the electrode and biomaterial interface can be designed to meet the complex requirements for high biophotoelectrochemical performance. Here we developed an aerosol jet printing method for generating hierarchical electrode structures using indium tin oxide nanoparticles. We printed libraries of micropillar array electrodes varying in height and submicrometre surface features, and studied the energy/electron transfer processes across the bio-electrode interfaces. When wired to the cyanobacterium Synechocystis sp. PCC 6803, micropillar array electrodes with microbranches exhibited favourable biocatalyst loading, light utilization and electron flux output, ultimately almost doubling the photocurrent of state-of-the-art porous structures of the same height. When the micropillars' heights were increased to 600 mu m, milestone mediated photocurrent densities of 245 mu A cm(-2) (the closest thus far to theoretical predictions) and external quantum efficiencies of up to 29% could be reached. This study demonstrates how bio-energy from photosynthesis could be more efficiently harnessed in the future and provide new tools for three-dimensional electrode design. Wiring photosynthetic biomachineries to electrodes is promising for sustainable bio-electricity and fuel generation, but designing such interfaces is challenging. Aerosol jet printing is now used to generate hierarchical pillar array electrodes using indium tin oxide nanoparticles for high-performance semi-artificial photosynthesis.

Automated summary

The use of aerosol jet printing with indium tin oxide nanoparticles allows for the generation of hierarchical electrode structures that meet the complex requirements for high biophotoelectrochemical performance. The resulting micropillar array electrodes, when wired to cyanobacteria, exhibit significantly improved biocatalyst loading, light utilization, and electron flux output. This study demonstrates a promising approach to more efficiently harnessing bio-energy from photosynthesis and provides new tools for three-dimensional electrode design.