Enhanced photocatalytic activity of AgNPs-in-CNTs with hydrogen peroxide under visible light irradiation

Silver nanoparticles in carbon nanotubes (AgNPs-in-CNTs) were prepared through a simple thermal decomposition method. Synthesized AgNPs-in-CNTs were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). In the presence of hydrogen peroxide (H₂O₂), AgNPs-in-CNTs exhibited perfect photocatalytic activity in rhodamine B (RhB) degradation under visible light irradiation. Hydrogen peroxide (H₂O₂) concentration and initial pH values were comprehensively scrutinized. When the concentration of H₂O₂ was 20 mM, about 99.8% RhB (20 mg L^-1) could be degraded within 50 min while the initial pH (3-10) values had a negligible effect on the degradation. From the investigations of Raman spectroscopy, transient photocurrent responses, photoluminescence, and radical quenching experiments, the findings suggest that under light irradiation, AgNPs-in-CNTs can absorb photons and generate photogenerated electrons through localized surface plasmon resonance (LSPR) effect, the photogenerated electrons react with H₂O₂ to produce ·OH radicals for decomposing RhB.