Mesoporous and macroporous Ag-doped Co3O4 nanosheets and their superior photo-catalytic properties under solar light irradiation

An ideal photocatalyst should have a wider absorption capacity, a larger surface area, a narrow optical band gap, a better electronic conductivity, a lower load transfer resistance and a minimum charge recombination probability. Herein, mesoporous and macroporous nanosheets of Ag·Co3O4 have been synthesized via a two-step hydrothermal and post-annealing approach. The catalytic activities of the doped and undoped Co3O4 samples were tested and compared using Methylene Blue dye (MB) as a model pollutant. The specific surface area, optical band gap, electrical conductivity, and charge transfer resistance of the fabricated samples were analyzed using BET, UV/Visible, I–V, and EIS analyses. The Ag·Co3O4 sample showed a higher catalytic aptitude than the pristine Co3O4 sample because it degrades comparatively higher concentration of MB dye at a faster rate under natural sunlight irradiation. Specifically, the Ag·Co3O4 sample eliminated 88.4% MB dye at the rate constant (k) of 2.1 × 10−2 min−1 in only 90 min of solar irradiation. The outstanding removal efficiency and higher rate performance of the Ag·Co3O4 sample is attributed to its novel bimodal-porous structure, higher surface area (258 m2 g-1), narrow bandgap (1.55 eV), good electrical conductivity (1.5 × 105 Sm−1) and smaller charge transfer resistance. The exceptional activity of the Ag·Co3O4 sample under solar irradiation reveal its greatest potential to eliminate toxic and harmful dyes from industrial effluents.