Nonmetallic Abiotic-Biological Hybrid Photocatalyst for Visible Water Splitting and Carbon Dioxide Reduction

iScience. 2020 Jan 24;23(1):100784. doi: 10.1016/j.isci.2019.100784. Epub 2019 Dec 19.

Abstract

Both artificial photosystems and natural photosynthesis have not reached their full potential for the sustainable conversion of solar energy into specific chemicals. A promising approach is hybrid photosynthesis combining efficient, non-toxic, and low-cost abiotic photocatalysts capable of water splitting with metabolically versatile non-photosynthetic microbes. Here, we report the development of a water-splitting enzymatic photocatalyst made of graphitic carbon nitride (g-C3N4) coupled with H2O2-degrading catalase and its utilization for hybrid photosynthesis with the non-photosynthetic bacterium Ralstonia eutropha for bioplastic production. The g-C3N4-catalase system has an excellent solar-to-hydrogen efficiency of 3.4% with a H2 evolution rate up to 55.72 μmol h-1 while evolving O2 stoichiometrically. The hybrid photosynthesis system built with the water-spitting g-C3N4-catalase photocatalyst doubles the production of the bioplastic polyhydroxybutyrate by R. eutropha from CO2 and increases it by 1.84-fold from fructose. These results illustrate how synergy between abiotic non-metallic photocatalyst, enzyme, and bacteria can augment solar-to-multicarbon chemical conversion.

Keywords: Catalysis; Energy Materials; Microbial Biotechnology.