Nano Copper Oxide: From Flame Spray Pyrolysis to Photoelectrochemical Hydrogen Generation

A systematic experimental study of the synthesis of copper oxide nanoparticles and nanoporous films is presented. Powders were made by flame spray pyrolysis method with end applications in the photoeclectrochemical production of hydrogen. Inhibited particle growth was observed for prticles made from 1M copper nitrate (~22%w/w copper nitrate/solution) precursor using a liquid nitrogen gas cooling. The average diameter was 12 nm with a standard deviation of 5 nm. In comparison, particles formed without the additional cooling had an average diameter of 16 nm with a standard deviation of 9 nm. The particle morphology was near spherical and with the fractal dimension (Df) around 3. With a decrease in the precursor concentration to 0.48% w/w copper nitrate/solution, fractal-type aggregate with fractal dimension (Df) around 1.9 were obtained, which may be attributed to a transition to diffusion limitation aggregation for the lower precursor concentration. Downstream research into making copper oxide thin film electrodes for photoelectrochemical applications was done by spin coating and doctor blade casting of copper oxide nanoparticles suspension. The behavior of two film preparation process was compared by investigating surface morphology and resulting photocurrent density. In case of films made by spin coating, a uniform surface was observed, however, for films made by doctor blade casting, porous films with diameter of 400nm holes were obtained. The reason of forming different film morphology might be attributed to the evaporation rate of solvent during the drying process. Results for effects of morphology on photocurrent density will be present.