Photocatalytic Hydrogen Generation by Monodisperse TiO<sub>2</sub> Nanoparticles Singly and Dually Doped with Niobium and Tantalum
Nhat M. Ngo, Minh Dang Nguyen, Hung-Vu Tran, Riddhiman Medhi, Jong Moon Lee, T. Randall Lee
Abstract
Despite the many advantageous characteristics of an excellent photocatalyst for large-scale applications, some critical challenges still hinder the prospects of titanium dioxide. While judicious doping and nanoscale fabrication offer logical avenues for improvement, most of these methods require complex processes under demanding conditions, which are undesirable for scale-up. In the work reported here, highly monodisperse spherical nanoparticles of undoped, singly doped (NTO and TTO), and dually doped (NTTO) anatase TiO 2 using niobium and tantalum as dopants were prepared by scalable methods under mild conditions. The doped TiO 2 nanoparticles showed reduced band gap energies and adjustable suppressions of the rate of electron–hole recombination, with the largest reductions observed for the heretofore unreported dually doped NTTO nanoparticles. Furthermore, the introduction of Nb and/or Ta dopants into the TiO 2 lattice also substantially improved the photocatalytic hydrogen evolution rates and quantum yields, with the NTTO nanoparticles achieving the highest performance in both metrics. Importantly, all these nanoparticles maintained high stability after multiple photocatalytic hydrogen evolution test cycles, indicating that doped TiO 2 nanoparticles have significant potential for use in photocatalytic fuel generation and related optoelectronic applications.