A method of manufacturing plate-like shaped catalytic nanoparticles attached to a catalyst support structure comprising: (a) selecting prepared or purchased, photosensitive precursors being one or more metal organic complexes each comprising a metal ion and at least one type of organic ligand and the organic ligand is volatile, with a low boiling point, is easily soluble in suitable organic solvents, does not polymerise when exposed to irradiation, and does not inappropriately react with the support material, (b) dissolving the selected metal complex precursors in an organic solvent to form a clear precursor solution, c) dispersing a non-soluble support material into a selected organic solvent until the support material is homogenized in the solvent to form a support material solution. d) mixing the precursor solution and the support material solution to form a mixed solution and stirring for a period of time to allow the metal organic complex molecules to adsorb on the surface of the support material, e) irradiating the mixed solution using irradiation means suitable for decomposing the photosensitive metal organic complex for a desired time with periodic shaking of the mixed solution until the ligands are decomposed from the metal ions, thereby converting the metal organic complex molecules into metal or metal oxide nanoparticles at least some of which are the catalytic nanoparticles and the fragments of the organic ligands are all soluble in the solvent, and f) separating the catalyst product from the mixed solution, thereby removing the fragment of organic ligands and solvent by centrifuging, separation, washing, and/or evaporation. (a) selecting prepared or purchased, photosensitive precursors being one or more metal organic complexes each comprising a metal ion and at least one type of organic ligand and the organic ligand is volatile, with a low boiling point, is easily soluble in suitable organic solvents, does not polymerise when exposed to irradiation, and does not inappropriately react with the support material, (b) dissolving the selected metal complex precursors in an organic solvent to form a clear precursor solution, c) dispersing a non-soluble support material into a selected organic solvent until the support material is homogenized in the solvent to form a support material solution. d) mixing the precursor solution and the support material solution to form a mixed solution and stirring for a period of time to allow the metal organic complex molecules to adsorb on the surface of the support material, e) irradiating the mixed solution using irradiation means suitable for decomposing the photosensitive metal organic complex for a desired time with periodic shaking of the mixed solution until the ligands are decomposed from the metal ions, thereby converting the metal organic complex molecules into metal or metal oxide nanoparticles at least some of which are the catalytic nanoparticles and the fragments of the organic ligands are all soluble in the solvent, and f) separating the catalyst product from the mixed solution, thereby removing the fragment of organic ligands and solvent by centrifuging, separation, washing, and/or evaporation.