Linearly Polarized Laser Tailored Charge Spatial Separation of Asymmetric TiO ₂ Nanobelts for Photocatalytic Hydrogen Evolution

How to further improve the spatial separation of photogenerated carriers and the efficiency of hydrogen production remains a significant challenge in photocatalytic water splitting. The integration of linearly polarized lasers as a light source with asymmetric TiO₂ nanobelts (TiO₂ NBs) as photocatalysts has been shown to potentially enhance laser-induced photocatalytic hydrogen production. Herein, the significant role and underlying mechanism of linearly-polarized-laser in tailoring spatial charge separation of asymmetric TiO₂ NBs through inducing polarization electric field is revealed. By deliberately introducing the electric field vector of the laser to align (parallel or perpendicular) with the nanobelts' longitudinal dimension, the photogenerated current density is maximized or minimized, respectively. This provides direct evidence on the critical role of the polarization electric field for rational spatial separation of the photogenerated electrons. The linearly polarized laser tailored asymmetric TiO₂ NBs exhibit excellent photocatalytic H₂ production activity of 3.04 mmol h^-1 g^-1 in pure water with good stability. The performance is approximately 76 times greater than that under Hg lamp conditions and 1.9 times of symmetric P25 nanoparticles (NPs) under the same laser conditions. These findings provide a strategy to boost spatial charge separation by the synergistic effect of laser and asymmetric nanostructures for photocatalytic hydrogen production in pure water.