Iron Pyrite/Titanium Dioxide Photoanode for Extended Near Infrared Light Harvesting in a Photoelectrochemical Cell

The design of active and stable semiconducting composites with enhanced photoresponse from visible light to near infrared (NIR) is a key to improve solar energy harvesting for photolysis of water in photoelectrochemical cell. In this study, we prepared earth abundant semiconducting composites consisting of iron pyrite and Titanium oxide as a photoanode (FeS 2/TiO 2 photoanode) for photoelectrochemical applications. The detailed structure and atomic compositions of FeS 2/TiO 2 photoanode was characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), inductively coupled plasma with atomic emission spectroscopy (ICPAES) and Raman spectroscopy. Through the proper sulfurization treatment, the FeS 2/TiO 2 photoanode exhibited high photoresponse from visible light extended to near infrared range (900 nm) as well as stable durability test for 4 hours. We found that the critical factors to enhance the photoresponse are on the elimination of surface defect of FeS 2 and on the enhancement of interface charge transfer between FeS 2 and TiO 2. Our overall results open a route for the design of sulfur-based binary compounds for photoelectrochemical applications.