Anodic formation of self-organized cobalt oxide nanoporous layers

Nanoporous materials: High-aspect-ratio, ordered porous Co ₃O₄ layers were formed by self-organizing anodization of a cobalt substrate and subsequent annealing. The key for successful formation of such layers is to sufficiently suppress competing oxygen evolution during anodization. The aligned Co₃O₄ channel layers behave as a highly efficient water oxidation catalyst (see picture).