Graphene Oxide and Polyelectrolyte Composed One-Way Expressway for Guiding Electron Transfer of Integrated Artificial Photosynthesis

A novel photocatalyst/biocatalyst integrated artificial photosynthesis system (APS) based on polyurethane hollow nanofibers doped with graphene oxide (GO) and poly(allylamine hydrochloride) (PAH) was developed and employed for selective methanol conversion from CO₂. The biocatalysts, including formate, formaldehyde, and alcohol dehydrogenases, as well as NAD⁺, were in situ coencapsulated inside the lumen of the GO-PAH-doped PU nanofibers (G-Fiber) by simply predissolving them in the core-phase solution for coaxial electrospinning, while the precise assembling of the photocatalyst parts involving visible light active photosensitizer (PS) and electron mediator (M) on the surface of the G-Fiber was realized by their π- π interactions with the GO doped in the shell of fibers. By using this highly integrated APS, about 10-times higher methanol yield was accomplished as compared with the solution-based system. The significantly enhanced reaction efficiency of the G-Fiber-based APS is considered predominately due to the electron transfer "one-way expressway" composed of the doped polyelectrolyte and GO in the G-Fiber; therefore, the electron-transfer distance along the PS-M-NAD⁺ electron transport chain could be shortened and the speed could be accelerated. As a consequence, the electron back-flow between PS and M, as well as the recombination of the excited electron and the hole of PS were eliminated. The current work will represent a new benchmark for solar-energy driven conversion of CO₂ to a wide range of fuels and chemicals in an environmentally benign manner.