RESUMO
Low temperature synthesis of ZnO particles without using reactive materials, solvents and post-treatments is still a serious challenge for both fundamental research and industrial applications. In this research, we report the dry synthesis of ZnO particles only by using Zn(acac)2 and supercritical CO2 (scCO2) at the low temperature of 60 °C. The synthesis was performed using CO2 and N2 from 0.1 to 30.0 MPa for 18 h. As a result, ZnO yields increased with a rise in the CO2 pressure and reached 67% at 30.0 MPa while N2 medium gave low yields below 4.9% regardless of the pressure. Additionally, the detailed characterization results and the phase behavior observations evidentially showed the formation of zinc-CO/CO2-organic complexes in the solid phase of Zn(acac)2 powder under scCO2, resulting in the accelerated formation of ZnO particles. These findings suggest that scCO2 has potential value to drive the formation reaction of zinc-CO/CO2-organic complexes, which allows the low temperature synthesis of ZnO particles under dry conditions without using reactive materials, solvents and post-treatments.