Fabrication of novel AgIO4/TiO2 heterojunction for photocatalytic hydrogen production through direct Z-scheme mechanism

Abstract

In this research, novel AgIO4/TiO2 heterojunctions with high photocatalytic hydrogen production efficiency were fabricated by sonochemical route. XRD, N2-adsorption–desorption isotherm, DRS, PL, XPS and HRTEM analysis are carried out for investigating the physicochemical properties of the photocatalyst. Noticeably, XRS, HRTEM, DRS and PL results reflect the shift in the crystalline diffraction peaks, distortion in the nanostructure, narrowing the band gap energy and reduction in PL intensity revealing the successful construction of AgIO4/TiO2 heterojunction. The as-achieved AgIO4/TiO2 nanocomposites exhibit an excellent hydrogen evolution rate of nearly 8.4 mmol h−1 g−1 which is 40 times higher than that of bare TiO2 with methanol as a sacrificial agent. The excellent photocatalytic hydrogen production reactivity was attributed to direct Z-scheme mechanism in which the positive holes in the valence band of TiO2 and electrons in the conduction band of AgIO4 are recombined; however, the electrons and holes of titania and AgIO4 are preserved with strong reductive and oxidative powers. This novel Z-scheme mechanism between two different semiconductors gives an innovation vision for production of huge amount of hydrogen gas through simple clean route.