An apparent quantum efficiency (AQE) of 40% for the photo-reduction of bicarbonate to value-added formate was achieved by designing a novel thin film semiconductor device with metallophthalocyanines as the photosensitizer. The thin film device was fabricated by the thermal deposition of 100 nm of semiconductor (TiO2 or Cu2O) and 100 nm of zinc or cobalt phthalocyanine. We attribute these extraordinary results to the synergistic, foliated design of the positive hole scavenger and photosensitizer. The photo-excited phthalocyanines can transfer its electrons into the conduction band of the semiconductor, enhancing the overall electron supply. As demonstrated in this study, thin films in the form of artificial foliage are of high practical value because the immobilization of TiO2 prevents agglomeration and maximizes surface area which allows for more bicarbonate adsorption and greater solar penetration. The ability to create the thin films via thermally depositing the photosensitizer and semiconductor allows for uniform layers without wasting material. Future studies include the use of transient absorption spectroscopy to confirm the mechanism of charge transfer from dye to semiconductor.

Artificial foliage with remarkable quantum efficiency in converting photons to formate

2019 Fall National Meeting

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