Solar-driven catalytic conversion of inert CO2 to value-added chemicals is an ambitious goal of ongoing research efforts. Photocatalysis with purely inorganic materials has generated insufficient results. While inorganic catalysts in particular semiconducting nanostructures have demonstrated apt light absorption, low selectivity, poor mass transfer and inadequate stability limit their utility. Our efforts consider a class of biological organisms that have evolved to achieve CO2 fixation. These microorganisms offer the advantage of highly selective CO2 reduction and self-regeneration at ambient pressure and temperature. We demonstrate the synergistic combination of whole microorganisms with the exceptional ability of semiconducting nanomaterials to harvest solar energy. Using light-active silicon nanowires, we are able to transfer reducing equivalents to bacteria and power their metabolic pathways. We achieve CO2 conversion into upgradeable acetate with high faradaic efficiency. We further discuss the photosensitization of bacteria with light-absorbing nanoparticles. This achieves a novel intracellular interface in which photoexcited charger carriers can be directly taken up thus bypassing sluggish kinetics of extracellular charge transfer. In particular, we present the use of gold nanoclusters as biocompatible photosensitizers. Finally, we show the successful extension of photosynthetic biohybrid systems for the reduction of inert N2 into NH3. By combining the strengths of nanostructured semiconductors and biology, we provide a solution for renewably powered catalysis.

Photocatalysis in semiconductor biohybrid systems

2019 Fall National Meeting

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