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.