Silver nanostructure-loaded starch functionalized magnetite (Ag/s-Fe3O4) photocatalyst for H2O2 production: experimental and molecular dynamics studies

Abstract

The present research investigates photocatalytic H₂O₂ formation on a composite of Ag and starch-stabilized Fe₃O₄ (denoted as s-Fe₃O₄) nanoparticles. Starch functionalization of the Fe₃O₄ part significantly improved the hydrophilicity of the composite. The charge carrier separation efficiency and photocatalytic activity changed with the amount of Ag loading on s-Fe₃O₄. H₂O₂ production on this photocatalyst was investigated in pure water and aqueous solutions of various green sacrificial agents like glycerol. Classical molecular dynamics (MD) was employed to study the adsorption affinity of O₂ and H₂O on the surface of Fe₃O₄, s-Fe₃O₄, and Ag/s-Fe₃O₄ in an aqueous medium. MD results indicate that functionalizing Fe₃O₄ with starch (s-Fe₃O₄ system) enhances water adsorption affinity, and precipitating Ag nanostructures on s-Fe₃O₄ (Ag/s-Fe₃O₄) increases O₂ adsorption affinity. Water contact angle measurements on Fe₃O₄, s-Fe₃O₄, and Ag/s-Fe₃O₄ nanoparticles also quantify significantly better water adsorption due to starch functionalization. An aqueous solution of glycerol exhibited the best photocatalytic H₂O₂ production activity. This result is critical given that glycerol is green, economical, and a byproduct of the biodiesel industry. A photocatalysis mechanism for H₂O₂ generation on Ag/s-Fe₃O₄ photocatalysts has been proposed based on a series of control experiments and molecular dynamics simulations.