Tailored Assembly of Biomimetic Nacre-Like Catalytic Multilayers for Artificial Photosynthesis

Abstract

Artificial photosynthesis has been considered a promising solution to global energy and environmental issues as it allows sustainable production and the use of valuable chemicals (e.g., formate, synthesis gas, and methanol) from abundant carbon dioxide and water through a series of photoelectrochemical processes. For the successful development of efficient and stable photosynthetic devices, it is critically required to precisely assemble various functional materials for efficient exciton generation, exciton dissociation, charge transport, and electrocatalytic charge transfer reactions. Here, we report the development of an efficient and stable hematite-based photoanode for solar water oxidation using biomimetic nacre-like catalytic multilayers (CMs), which was fabricated using the layer-by-layer assembly of cationic graphene oxide (GO) nanosheets and anionic molecular metal oxide catalysts. The nacre-like CMs not only resemble the mesoscale organization of thylakoid organelles of plants but also significantly improve the photocatalytic performance of the underlying hematite photoanode with a huge cathodic shift of onset potential for water oxidation and remarkable increase of photocurrent. Unexpectedly, it was also found that deposition of alternating layers of cationic and anionic polymers prior to the artificial nacre film allowed fine-tuning of the work-function of the hematite electrode by the surface dipole effect. We believe that our biomimetic approaches can provide a general and simple method to fabricate an efficient photosynthetic device, as well as an insight to scientists and engineers for designing a novel electrochemical/photoelectrochemical device.