Hydrogen Productivity Analysis Using Low Concentration of TiO2–Au Nanoparticles on a Ultraviolet-LED-Based Photocatalytic Reactors

Abstract

The productivity of photocatalytic hydrogen generation via photo-reforming of organic compounds has not been studied under low concentrations of catalyst, which could lead to relevant cost savings in future real-scale applications. Herein, it uses half of the lowest concentration of nanoparticles reported of modified P25 TiO2 partially coated with gold. The nanomaterial is prepared using a non-energy intensive, chemical reduction method. Gold content on the TiO2 surface is reported (14%—surface; 9.1%—weight). Dynamic light scattering and transmission electron microscope image analyses show low agglomeration and non-homogeneous shape. Aggregates and gold nanoparticles reach average diameters of 92 and 3.8?nm, respectively. Photocatalytic experiments for hydrogen production are carried out at low concentration of nanoparticles (0.056?g?L?1) in methanol–water solution (5%vol.) under 375?nm UV and visible light (20?mW?cm?2). The system shows a catalyst productivity of 6661??mol?h?1?g?1, a third of the highest reported productivity using methanol (which used a catalyst concentration 18× higher, an alcohol concentration 5× higher, and 100% anatase). The system shows an estimated reaction rate of 373??mol?L?1?h?1 with an apparent zero order kinetic, an overall energy conversion efficiency of 0.47%, and an apparent quantum yield of 1.03%.