Large Conjugated Organic Cations Sensitized Hybrid Lead Halides as Visible Light Driven Photocatalysts

Visible light driven photocatalysts based on crystalline metal halides received much less attention compared with dense or composite oxide semiconductors due to low photochemical stabilities. Here, by using large conjugated organic cations as structural direction agents, a series of hybrid cuprous and/or lead halides have been solvothermally prepared and structurally characterized. Compounds H[(Me)3-TPT]6(Cu2I6)3(Pb6I19)·(H2O)2 (1) and [(Me)3-TPT]2Cu2Pb3Br14 (2; TPT = 2,4,6-tri(4-pyridyl)-1,3,5-triazine) contain uncommon Lindqvist-type [Pb6I19]7– nanoclusters and heterometallic [Cu2Pb3Br14]6– units, respectively. Compounds [H3TIB]2Pb5Br16 (3) and H[(Me)3-TIB]2Pb5I17 (4; TIB = 1,3,5-tris(1-imidazolyl)benzene) are composed of one-dimensional (1D) [Pb5Br16]6– chains and two-dimensional (2D) [Pb5I17]7– layers, respectively. The photosensitized conjugated organic cations offer a great contribution to the conduction bands, which lead to narrow band gaps of 2.01–2.35 eV. Under visible light irradiation, compound 4 exhibits efficient and stable photocatalytic degradation activity for various organic pollutants. The possible photocatalytic mechanism obtained from the radical trapping experiments and electronic band structural calculation show that conjugated organic cations effectively inhibit the recombination of photoinduced electron–hole pairs leading to excellent photocatalytic activity and photochemical stability.