Chemical-Bond-Mediated p-n Heterojunction Photocatalyst Constructed from Coordination Polymer Nanoparticles and a Conducting Copolymer: Visible-Light Active and Highly Efficient.

A visible-light-active p-n heterojunction photocatalyst has been synthesized by the enwrapping of poly[aniline-co-N-(4-sulfophenyl)aniline] (PAPSA) on a coordination polymer nanoparticle (NCP). Compared with the visible-light-inactive NCP, the new p-n heterojunction photocatalyst, PAPSA/NCP, exhibits a much higher efficiency in the reduction of Cr(VI) under visible light. PAPSA performs two functions in this p-n heterojunction photocatalyst. First, as a visible-light-active material, it extends the photoresponse region of the photocatalyst from the ultraviolet to the visible-light region. Secondly, as a p-type semiconductor possessing suitable energy levels with respect to NCP, PAPSA forms a p-n heterojunction with the n-type NCP; the inner electric field of the p-n heterojunction accelerates the separation of electrons and holes, which enhances the photocatalytic efficiency. Furthermore, the p-n heterojunction photocatalyst exhibits outstanding stability during the photocatalytic reduction of Cr(VI) .