Ag 0 /Au 0 nanocluster loaded Bi 2 O 4 photocatalyst for methyl orange dye photodegradation.

Visible-light-sensitive Ag and Au nanocluster loaded Bi 2 O 4 (Ag-Bi 2 O 4 and Au-Bi 2 O 4 ) semiconductor photocatalysts have been synthesized. The composite materials exhibited increased photocatalytic degradation of the azo-dye pollutant, Methyl Orange (MO). In addition, Au-Bi 2 O 4 (Au-7% wt) showed the highest MO degradation rate (0.05904 min -1 ) i.e. 7.69 times higher than the pristine Bi 2 O 4 and 1.4 times higher than 1% Ag-Bi 2 O 4 . The optical properties of the composites showed that the band gaps of the composite samples 1% Ag-Bi 2 O 4 and 7% Au-Bi 2 O 4 were 1.96 eV and 2.09 eV, respectively. The increase in the degradation rate is attributed to the decrease of the recombination rate of photoinduced e - /h + , caused by the enhanced charge transfer between the metal nanoparticles and Bi 2 O 4 as confirmed in the photocurrent measurements. The photocurrent measurements showed increase in the transients output by 8.25 times and 2.75 times for 1% Ag-Bi 2 O 4 & 3% Au-Bi 2 O 4 , respectively as compared to that of the pristine Bi 2 O 4 . These features further aided the increase in the photocatalytic efficiency while retaining the original physical properties, thus showing the robustness of Bi 2 O 4 as a photocatalyst.