Ag2S/CdS/Ni ternary nanostructures: long-range electric field to enhanced photocatalytic hydrogen production activity

Abstract

Silver sulfide, cadmium sulfide and nickel (Ag2S/CdS/Ni) ternary nanostructures were fabricated by a two step process and characterized by x-ray powder diffraction, transmission electron microscopy, and UV–vis diffuse reflection spectroscopy. The photocatalytic hydrogen production activity of ternary nanostructures and reference samples were evaluated using triethanolamine (TEOA) as sacrificial reagent in water under visible-light illumination (λ ≥ 420 nm). The result shows Ag2S/CdS/Ni nanostructures exhibited a high visible light photocatalytic H2 evolution rate of 1.54 mmolh−1 g−1, which was 4.6 times and 1.4 times higher than that of 1.2% mol Ag2S/CdS and Ni/CdS. The degree of photocorrosion of CdS were employed to study the photogenerated carriers transfer route by measuring and comparing the concentration of Cd2+ in the solution of the photocorrosion experiments in a nonsacrificial system. A long-range electric field, which is similar to the p-i-n electric field structure, was proposed to be constructed by Ni nanoparticles and Ag2S nanoparticles in CdS. Most of the photogenerated electrons and holes in CdS drift to the electron donor and electron acceptor respectively under the action of long-range electric field, which greatly improves the separation efficiency of photogenerated carriers and the photocatalytic H2 production activity.