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.