Facet-engineering palladium nanocrystals for remarkable photocatalytic dechlorination of polychlorinated biphenyls

Rationally constructing functionalized cocatalysts for removing chemically inert polychlorinated biphenyls is significant and challenging. In this work, we have synthesized uniform Pd nanocrystals (Pd NCs) with cube (CUB) and octahedron (OCT) geometry, corresponding to exposed (100) and (111) facet, respectively, and they were incorporated with ultrathin TiO2(B) nanosheets (TBs) for photocatalytic dechlorination of polychlorinated biphenyls under visible light illumination (λ≥400 nm). Photocatalytic performance experiments exhibit that CUB/TBs is more efficient with a 200% enhancement higher than OCT/TBs. Physicochemical characterizations reveal that the CUB possesses higher surface charge density than OCT, which promotes the activation of the C-Cl bond of polychlorinated biphenyls, leading to higher dechlorination performances of CUB/TBs than OCT/TBs. This work not only fundamentally elucidates the effect of facet-engineering palladium nanocrystals on photocatalytic dechlorination of polychlorinated biphenyls, but also paves the way for rationally fabricating superior photocatalysts for other advanced applications.