Morphologically and hierarchically controlled Ag/Ag2MoO4 microspheres for photocatalytic hydrogen generation

Abstract

This paper describes the synthesis of a novel spherical-shaped Ag/Ag2MoO4 nanocomposite using phosphomolybdic acid as the initial reaction precursor in a single-step photoreduction process, as well as its application for water-splitting hydrogen production. The formation of interconnected Ag/Ag2MoO4 spheres with an average diameter of 1–2 μm has been revealed by morphological details. The presence of metallic Ag on the surface of Ag2MoO4 with an average particle size of 0.5–1 nm was confirmed by the apparent resolution of transmission electron microscopic images and X-ray photoelectron spectroscopic details. The optical characterization suggested that metallic Ag NPs have an SPR effect. These Ag nanoparticles, when combined with phosphomolybdic acid, increased light absorptivity, resulting in a blueshift in the energy gap. The novel photochemical synthesis method resulted in the disorder–order structure and oxygen vacancies created during preparation for possible suppression of electron-hole recombinations. Under UV–Visible irradiation, the photocatalytic performance of the as-synthesized composite was tested for hydrogen production using ethanol as a sacrificial donor and Pt-as cocatalyst. Metallic Pt deposition on the surface of an Ag/Ag2MoO4 nanocomposite synergistically enhanced electron transport and accelerated proton reduction at an unprecedented rate. Despite the fact that the nanocomposite contains only 0.3% Pt0, the photocatalytic hydrogen production rate reached 0.4 mmol/h/g and remained stable at 0.63 mmol after four cycles of continuous catalytic process.. In 24 h of continuous reaction, total hydrogen evolution of 0.8 mmol was obtained by photocatalytic water splitting reaction with Pt0.3%/Ag/Ag2MoO4 nanocomposite without ethanol replenishment. The manuscript represents a novel synthesis approach for the development of spherical Ag/Ag2MoO4 nanocomposite imparting significant contribution towards practical application PMA based composite for various photocatalytic applications.