Pulsed-Laser-Triggered Piezoelectric Photocatalytic CO₂ Reduction over Tetragonal BaTiO₃ Nanocubes.

Abstract

The recombination of photoinduced carriers in photocatalysts is considered one of the biggest barriers to the increase of photocatalytic efficiency. Piezoelectric photocatalysts open a new route to realize rapid carrier separation by mechanically distorting the lattice of piezoelectric nanocrystals to form a piezoelectric potential within the nanocrystals, generally requiring external force (e.g., ultrasonic radiation, mechanical stirring, and ball milling). In this study, a low-power UV pulsed laser (PL) (3 W, 355 nm) as a UV light source can trigger piezoelectric photocatalytic CO₂ reduction of tetragonal BaTiO₃ (BTO-T) in the absence of an applied force. The tremendous transient light pressure (5.7 × 10⁷  Pa, 2.7 W) of 355 nm PL not only bends the energy band of BTO-T, thus allowing reactions that cannot theoretically occur to take place, but also induces a pulsed built-in electric field to determine an efficient photoinduced carrier separation. On that basis, the PL-triggered piezoelectric photocatalytic CO₂ reduction realizes the highest reported performance, reaching a millimole level CO yield of 52.9 mmol g^-1 h^-1 and achieving efficient photocatalytic CO₂ reduction in the continuous catalytic system. The method in this study is promising to contribute to the design of efficient piezoelectric photocatalytic reactions.