Binder-free three-dimensional Co3O4 electrodes are fabricated by an economical and scalable one-step flame combustion method, namely Reactive Spray Deposition Technology. The electrodes are composed of porous nanostructured Co3O4 uniformly distributed throughout the conductive substrate. In the absence of any further optimization on the processing conditions, the as-synthesized electrodes demonstrate high capacitance of 567 F g−1 at 1.5 A g−1, excellent rate capability, and stable cycling performance with a capacity retention ratio of 96.7% after 1000 charge/discharge cycles from the three-electrode half-cell testing. This study presents the pathway to a significantly simplified manufacturing process of three-dimensional electrodes with the desirable porous nanostructure.

Efficient catalysts for the oxygen evolution reaction (OER) are widely applied in fuel cells and rechargeable lithium air batteries. It is desirable but challenging to achieve comparable activity to that of the noble-metal catalyst with non-precious metal catalyst. Highly active Co3O4 thin film electrodes have been successfully synthesized by a rapid one-step flame combustion synthesis method called Reactive Spray Deposition Technology. X-ray diffraction confirms the absence of any impurity phase with this synthesis process. The detailed morphology of the Co3O4 thin film is investigated with scanning electron microscopy and transmission electron microscopy. Cyclic voltammetry is used to investigate the redox activity of Co3+ to Co4+ which is crucial for the OER performance. The as-prepared Co3O4 catalyst demonstrates promising activity for OER, with an overpotential of 399 mV (at 10 mA cm-2) for OER.

Lanthanum zirconate (La2Zr2O7) nano-crystalline films with cubic structure have been successfully prepared by a facile synthesis approach called reactive spray deposition technology (RSDT). La2Zr2O7 nanoparticles are produced by combusting a precursor solution of lanthanum acetylacetonate hydrate and zirconium acetylacetonate dissolved in an organic solvent mixture. The nanoparticles formed during the combustion process are directly deposited onto the substrate. The composition and microstructure of the as-deposited films are extensively characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The thermal diffusivities of the films are investigated by the means of laser flash method.