Synthesis and cathodoluminescence properties of porous wood (fir)-templated zinc oxide

Wood (fir)-templated ZnO with hierarchically porous structure has been successfully synthesized through a simple hydrothermal process. Morphology and porosity of the products were investigated by FESEM, TEM, and N2 adsorption, respectively. The optical properties were measured by cathodoluminescence (CL) at room temperature. The morphologies of bulk and ground flake ZnO show an inheritance from the fir microstructure. Experimental results suggest that a higher calcination temperature will influence the grain size and porosity. The pore size decreases from 20 to 10 μm in the bulk ZnO, while increases from 50 nm to several micrometers in the flake ZnO when the calcination temperature changes from 600 to 1200 °C. CL spectra also show temperature-dependent properties at ultraviolet (UV) band and blue band. The intensity of visible emission originated from oxygen vacancies is proportional to the calcination temperature, while that of UV emission is inverse proportional due to quantum confinement effect.