Unveiling Dynamic Structure and Bond Evolutions in BiOIO₃ Photocatalysts during CO₂ Reduction

We have established a correlation between photocatalytic activity and dynamic structure/bond evolutions of BiOIO₃-based photocatalysts during CO₂ reduction by combining operando X-ray diffraction with photoelectron spectroscopy. More specifically, the selective photo-deposition of PtO_x species on BiOIO₃ (010) facets could effectively promote the electron enrichment on Bi active sites of (100) facets for facilitating the adsorption/activation of CO₂ molecules, leading to the formation of Bi sites with high oxidation state and the shrink of crystalline structures. With introducing light irradiation to drive CO₂ reduction, the Bi active sites with high oxidation states transformed into normal Bi³⁺ state, accompanying with the expansion of crystalline structures. Owing to the dynamic structure, bond, and chemical-state evolutions, a significant improvement of photocatalytic activity for CO evolution has been achieved on PtO_x-BiOIO₃ (195.0 μmol g^-1 ⋅ h^-1), much higher than the pristine (61.9 μmol g^-1 ⋅ h^-1) as well as metal-Pt decorated BiOIO₃ (70.3 μmol g^-1 ⋅ h^-1) samples. This work provides new insights to correlate the intrinsically dynamic structure/bond evolutions with CO₂ reduction activity, which may help to guide future photocatalyst design.