MgTiO₃/MgTi₂O₅/TiO₂ heterogeneous belt-junctions with high photocatalytic hydrogen production activity

An effective photocatalytic hydrogen production catalyst comprising MgTiO₃/ MgTi₂O₅/TiO₂ heterogeneous belt-junctions was prepared using magnesium ions by a thermally driven doping method. The tri-phase heterogeneous junction was confirmed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The as-prepared MgTiO₃/MgTi₂O₅/ TiO₂ heterojunctions exhibited a very high photocatalytic hydrogen production activity (356.1 mol∙g_0.1gcat∙h⁻¹) and an apparent quantum efficiency (50.69% at 365 nm) that is about twice of that of bare TiO₂ nanobelts (189.4 mol∙g_0.1gcat∙h⁻¹). Linear sweep voltage and transient photocurrent characterization as well as analysis of the electrochemical impedance spectra and Mott-Schottky plots revealed that the high photocatalytic performance is caused by the one-dimensional structure, which imparts excellent charge transportation characteristic, and the MgTiO₃/MgTi₂O₅/TiO₂ tri-phase heterojunction, which effectively drives the charge separation through the inherent electric field. This titanate-based tri-phase heterogeneous junction photocatalyst further enriches the catalyst system for photocatalytic hydrogen production.