Conversion of water and carbon dioxide into methanol with solar energy on Au/Co nanostructured surfaces

Abstract

Conversion of carbon dioxide (CO2) and water (H2O) to methanol (CH3OH) is achieved through an artificial photosynthesis procedure utilizing cobalt (Co) micro-particle based photocatalyst and solar energy in a simple, closed reactor. The photocatalyst is fabricated by exposing the surfaces of cobalt microparticles to femtosecond laser irradiation in a gold chloride (AuCl) solution. The morphology and composite of the photocatalyst surfaces were observed and detected to be a layer of cobalt dioxide (CoO) nano-flakes on which some gold (Au) nanoparticles were deposited. The Au nanoparticles harvest the Sunlight energy through a plasmonic effect. The energy absorbed by Au nanoparticles creates electrons and holes which excite the H2O and CO2 molecules adsorbed on CoO nanostructure surfaces to form excited hydrogen (H2) and excited carbon monoxide (CO) on the CoO surface. The excited molecules combine to form CH3OH on the CoO surface. The Au/CoO/Co nanostructured surfaces are useful for developing a low-cost method to convert solar energy to chemical energy in the form of methanol.