Sonochemical synthesis of bismuth sulfide-based nanorods for hydrogen production

Bismuth-based nanostructures have been used as promising materials for catalytic hydrogen production. Herein, a sonochemical method was developed to prepare solid solutions like Bi2-xZn1.5xS3 in order to strengthen the Bi2S3 redox ability. Thioglycolic acid (TGA) was used as a complexing agent of Bi3+ to slow down Bi2S3 precipitation, making zinc insertion into the sulfide structure easier. The results of XRD, TEM, EDS, XPS, and DRS analyses suggest the formation of nanocomposites consisting of nanorods of Bi2-xZn1.5xS3 covered by ZnS nanoparticles, with bandgap widening from 1.16 eV (Bi2S3) to 2.37 eV (Bi1.53Zn0.6S3/ZnS/Zn(OH)2). The hydrogen generation in an ethanol aqueous solution was investigated under sonolysis, photocatalysis and simultaneous sonolysis and photocatalysis (sonophotocatalysis) in the presence of bismuth sulfide-based nanorods. The hybrid action of light and ultrasounds determined a remarkable synergistic effect on the hydrogen production of the solid solutions. The most outstanding results were found in the presence of nanocomposites containing Bi2-xZn1.5xS3, which can have an origin in better charge separation after zinc incorporation.