Autogenic reaction synthesis of photocatalysts for solar fuel generation

A photocatalyst for conversion of carbon dioxide and water into a hydrocarbon and oxygen, the photocatalyst comprising at least one metal oxide material that is substantially free of a carbon coating, prepared by heating a metal-containing precursor compound in a sealed reactor under a pressure autogenically generated by dissociation of the precursor material in the sealed reactor at a temperature of at least about 400° C. to form a nanoparticulate carbon-coated metal or metal oxide material, and subsequently substantially removing the carbon coating;

• wherein:
• the precursor material comprises a solid, solvent-free salt comprising a metal on and at least one thermally decomposable carbon- and oxygen-containing counter-ion;
• the metal oxide consists of a mixture of SnO2 nanoparticles and TiO2 nanoparticles;
• the SnO2 consists essentially of rutile SnO2 that is substantially free of a carbon coating, and is formed by thermal reaction of tin ethoxide in a sealed reactor at a temperature of about 600° C. under an autogenically generated pressure of up to about 100 pounds-per square-inch (psi) to form a nanoparticulate carbon-coated rutile SnO2 powder, and subsequently substantially removing the carbon coating;
• the TiO2 consists essentially of carbon-doped anatase TiO2 that is substantially free of a carbon coating, and is formed by thermal reaction of titanium acetoacetonate in a sealed reactor at a temperature of about 700° C. under an autogenically generated pressure of up to about 150 pounds-per square-inch (psi) to form a nanoparticulate carbon-coated anatase TiO2 powder, and subsequently substantially removing the carbon coating;
• the SnO2 nanoparticles have a particle size in the range of about 10 to about 20 nm;
• and the TiO2 nanoparticles have a particle size in the range of about 10 to about 30 nm.