Ag modified ZnO microsphere synthesis for efficient sonophotocatalytic degradation of organic pollutants and CO2 conversion

The synthesis and design of non-precious and efficient sonophotocatalyts by an environment friendly technique are requisites for solar energy conversion and environmental remediation. This work reports the preparation of Ag/ZnO microspheres with different Ag contents through deposition–precipitation method for pollutant degradation and CO2 conversion. Detail structural investigation reveals that ZnO microspheres and Ag-ZnO microspheres depicting spherical morphologies with smooth and rough surface respectively. The sonophotoactivties measured at 40 kHz frequency demonstrated that 3Ag/ZnO microsphere exhibited respectively 55 and 28-times improved sonophotoactivities for acid red 17 (AR-17) degradation and CO2 conversion compared with virgin ZnO microsphere. The obtained sonophoto-efficiencies for AR-17 degradation and CO2 conversion were found to be much higher compared to photo-efficiencies under visible-light due to the spatial synergistic effect of sono/photo waves. These unprecedented sonophotoactivities are credited to ultrasonic waves, rapid charge separation and promoted O2 activation. The factors such as the catalyst dosage, dye concentration, time, and temperature influencing the sono-efficiency of dye were also investigated. This continuous advancement has shown that ZnO microsphere-based nanocomposites are critical in the environmental remediation and solar energy generation.