Influence of Co 3 O 4 Nanostructure Morphology on the Catalytic Degradation of p-Nitrophenol.

The design and fabrication of nanomaterials with controllable morphology and size is of critical importance to achieve excellent catalytic performance in heterogeneous catalysis. In this work, cobalt oxide (CoO) nanostructures with different morphologies (nanoplates, microflowers, nanorods and nanocubes) were successfully constructed in order to establish the morphology-property-performance relationship of the catalysts. The morphology and structure of the nanostructured CoO were characterized by various techniques, and the catalytic performance of the as-prepared nanostructures was studied by monitoring the reduction of p-nitrophenol to p-aminophenol in the presence of excess NaBH. The catalytic performance was found to be strongly dependent on their morphologies. The experimental results show that the pseudo-first-order reaction rate constants for CoO nanostructures with various shapes are, respectively, 1.49 min (nanoplates), 1.40 min (microflowers), 0.78 min (nanorods) and 0.23 min (nanocubes). The CoO nanoplates exhibited the highest catalytic activity among the four nanostructures, due to their largest specific surface area, relatively high total pore volume, best redox properties and abundance of defect sites. The established correlation between morphology, property and catalytic performance in this work will offer valuable insight into the design and application of nanostructured CoO as a potential non-noble metal catalyst for p-nitrophenol reduction.