Facile synthesis of a Ag/AgCl/BiOCl composite photocatalyst for visible – light – driven pollutant removal

Abstract

Forerunner investigators of photocatalysis utilized TiO2 as the photocatalyst of choice. It has major drawbacks of which the most important one is that it is only activated under ultraviolet (UV) light irradiation. This high energy consumption made the process practically unfeasible. Solar energy (natural light and heat from sun) has great prospects with regards to acting as a substitute for UV light since it is a renewable and cheaper energy source. In this work, the development of a heterogeneous silver/ silver chloride/ bismuth oxychloride (Ag/AgCl/BiOCl) photocatalyst that is able to utilize natural light through visible light activation was investigated. This will successfully serve as a green alternative in the use of renewable energy for pollution reduction while saving energy. The synthesized photocatalysts were characterized using various techniques. The purity and crystallinity of the synthesized photocatalysts were determined using x-ray diffraction (XRD) while x-ray photoelectron spectroscopy (XPS) was used to determine the elemental composition and chemical states present in the synthesized catalysts as well as confirm the presence of elemental Ag. Fourier-transform infrared spectroscopy (FTIR) specified the functional groups present while the morphology and chemical composition were determined using a scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The surface area and pore size were measured on a Brunauer-Emmett-Teller (BET) and thermogravimetric analysis (TGA) was done to determine the thermal degradation of synthesized particles. Ultraviolet-visible spectroscopy (UV–vis) was done to determine the photoabsorption range and bandgap of the particles as efficiency of photocatalysis is dependent on these properties together with the morphology of the semiconductor material. Ag/AgCl/BiOCl photocatalyst showed good photocatalytic activity of 52 % under a low-wattage simulated visible light irradiation in 4 h. This work therefore shows great prospect for pollution control through energy reduction thereby protecting the environment.