Energy band modulation of N‐doped rutile/anatase TiO ₂ photoanode promoting charge separation toward prominent photoelectrochemical performance

Abstract

Abstract To solve the problem of high photogenerated carrier recombination rate and low photoelectric conversion efficiency of TiO 2 ‐based materials, a simple N‐doped anatase/rutile TiO 2 heterophase nanorod film was designed by a low‐temperature hydrothermal method in this work. The enhanced separation and transport of photogenerated charges were facilitated by the smaller contact barrier and appropriate band matching between anatase TiO 2 nanoparticles and rutile TiO 2 nanorods. The introduction of N doping in anatase TiO 2 resulted in an upward shift of the valence band and a narrowing of the band gap, consequently enhancing the efficiency of visible light utilization. The combination of the heterophase junction and N‐doping exhibited a synergistic effect, effectively suppressing the recombination of photogenerated charges and enhancing the photoelectric conversion efficiency of the photoanode. Under AM 1.5G irradiation, the photocurrent density ( J ) of the A‐TO(N)@R‐TONR photoanode reached 2.19 mA·cm −2 ( V RHE, 1.23 eV ). Additionally, the incident photon‐electron conversion efficiency (IPCE) and the charge injection efficiency ( η ) reached 81.4% and 51.6% at 320 nm. Furthermore, the J , IPCE, and η values of the A‐TO(N)@R‐TONR photoanode were 2.96, 2.1 and 3.2 times those of pure R‐TONR photoanode, respectively. This work presents a rational strategy for designing efficient TiO 2 ‐based photoanodes.