Strategies to Boost the Photocatalytic Activity in Halide Perovskite Nanocrystals

Colloidal halide perovskite nanocrystals (PNCs) are an ideal material for high photocatalytic activity, in addition to the tremendous attention already focused on optoelectronics such as light-emitting diodes and photovoltaics due to long charge carrier lifetime, narrow bandgap and facile wavelength tunability. Here, we report two strategies to improve photocatalytic activity based on colloidal CsPbBr₃ PNCs. First, we prepared CsPbBr₃ PNC/amorphous TiO₂ composites using hydrolysis of titanium butoxide in PNC dispersion under air ambient. High absorption coefficient and narrow bandgap of CsPbBr₃ can generate and transfer photo-excited electrons to the amorphous TiO₂, which performed 4.1 times higher photocatalytic CO₂ reduction efficiency (30.43 μmol g^-1 h^-1) than pristine CsPbBr₃ PNCs under outdoor sunlight (7.44 μmol g^-1 h^-1). Second, we doped Fe into CsPbBr₃ PNC via post-synthetic ion exchange method. Fe dopants induce dissociation of charge carriers while suppressing the recombination of them in the presence of external magnetic fields which prolong the lifetime of spin-polarized charge carriers. By application of both Fe dopants and external magnetic fields on the CsPbBr₃ PNCs, we achieved photocatalytic CO₂ reduction of 45.48 μmol g^-1 h^-1 in visible region which is 1.48 times higher than that of pristine CsPbBr₃ PNCs. These results provide simple paths toward efficient photocatalytic reaction in metal halide perovskite nanocrystals for CO₂reduction.