Laser-assisted electrohydrodynamic jet printing of hierarchical nanostructure

The hierarchical nanostructures had the advantages of large available space, specific surface area, low density, variable chemical composition, and controllable porosity, and have been widely used in energy, sensor, and catalysis. Traditional methods for preparing hierarchical nanostructures had limitations of a long process, few available materials, and un-customizable size. Electrohydrodynamic jet (E-Jet) printing is a competitive strategy for high-resolution printing. In this paper, a novel laser-assisted E-Jet printing employed a transient high-energy laser effect instead of a traditional continuously thermal effect for printing hierarchical nanostructure. The colorless ZnO ink was prepared with zinc acetate, diethanolamine, PVP, and ethanol. The transient thermal effect of laser irradiation focused a fine jet and induced Taylor cone expansion. The heat accelerated the solvent evaporation and increased the viscous force of the jet. The effects of laser on jet velocity, electric field, and jet behavior were analyzed theoretically. Characterization and 3D morphology of printed nanostructures with and without laser were investigated. The hierarchical nanostructures with size down to 180 nm could be laser-assisted E-Jet printed and its surface area increased multiply. The laser-assisted E-Jet printing method provides a simple, efficient, and low-cost strategy for preparing hierarchical nanostructure, having potential applications in high-performance devices.