Controllable synthesis of defective TiO2 nanorods for efficient hydrogen production

Abstract

Nanorods (NRs), with their high atomic surface exposure within a crystalline architecture, facilitate effective diffusion/transport of charge, rendering them particularly suitable for applications requiring both interaction with the media and charge transfer. In this study, we present a straightforward approach to produce brookite-phase titanium dioxide (TiO2) NRs with tunable defects and narrow size distributions by utilizing methylamine hydrochloride and 1,2-hexadecanediol as shape-directing agents. The presence of the Ti3+ defect was confirmed by electron paramagnetic resonance and X-ray photoelectron spectroscopy, and its effect on the photocatalytic properties of TiO2, with and without Pt loading, show that the longest TiO2 NRs provide the highest photocatalytic and photoelectrochemical hydrogen production activity. Transient photocurrent response analysis, electrochemical impedance spectroscopy, and Mott–Schottky analysis plots indicate that an increase in temperature significantly reduces the interface barrier and lowers the transport resistance, leading to a 104% improvement in hydrogen production rates from 25 to 60 °C for the longest TiO2 NRs. This study underscores the critical role of the TiO2 nanorod dimensions (18–45 nm) in elevating the hydrogen production efficiency. At 25 °C, rates surged from 1.6 to 2.6 mmol g–1 h–1, and at 60 °C, rates soared from 3.3 to 5.3 mmol g–1 h–1, demonstrating the substantial impact of TiO2 NRs on enhancing hydrogen generation.