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.