Vertically aligned and ordered hematite hierarchical columnar arrays for applications in field-emission, superhydrophilicity, and photocatalysis

We achieved the vertically aligned and ordered hematite hierarchical columnar arrays using pulsed laser deposition (PLD) with polystyrene (PS) colloid spheres as templates. Crystallized hematite hexagonalclose-packed columnar arrays are fabricated at room temperature and can be transformed to hexagonal-non-close-packed columnar arrays at an annealing temperature of 450 degrees C. The hierarchical columns consist of assembled nanoplates or nanoparticles, depending on the oxygen pressures during the PLD process. The improved performance in field emission (FE), surface wetting, and photocatalytic properties of the hematite hierarchical columnar arrays is due to the unique morphology of the superstructures and controlled compositions.