Nitrogen Doped 3D Titanium Dioxide Nanorods Architecture with Significantly Enhanced Visible Light Photoactivity

摘要

Surface-reaction-limited pulsed chemical vapor deposition (SPCVD) is able to create 3D TiO2-based hierarchical nanowire (NW) architecture with superhigh surface area and good electronic transport properties for high-performance photoelectrode development. However, how to intentionally dope the nanorods (NRs) through the SPCVD process to improve their electronic properties and light absorption behavior is still unexplored. In this paper, a comprehensive study of doping TiO2 NRs with nitrogen through the SPCVD technique is reported for the first time. The high-density nitrogen doped TiO2 NR branches with controlled doping concentrations were synthesized on dense Si NW forest by introducing designed number of TiN cycles to TiO2 growth cycles. Microscopic studies revealed the influence of nitrogen doping on the crystal growth behavior and NR morphology, as well as the elements distribution inside the lattices. Nitrogen doping lowered the band gap of TiO2 NRs and effectively activated visible light photoactivity. It also largely improved the incident-photon-to-current-conversion efficiency in the UV range. Successful synthesis of N doped TiO2 NRs by the SPCVD method introduces a strong new capability to this novel and powerful 3D NR growth technique. It enables composition and optoelectronic property control of the novel 3D NR structures, allowing performance enhancement or creating new functionality.