Comparison studies of hybrid lead halide [MPb2X7]2− (M = Cu, Ag; X = Br, I) chains: band structures and visible light driven photocatalytic properties

Abstract

By using transition-metal (TM) complex cationic dyes as structure-directing agents and photosensitizers, a series of inorganic–organic hybrid metal halides, namely, [TM(2,2′-bipy)₃]AgPb₂I₇ [TM = Ni (1), Co (2) and Zn (3)], [Co(2,2′-bipy)₃]CuPb₂Br₇ (4) and [TM(2,2′-bipy)₃]AgPb₂Br₇ [TM = Ni (5) and Fe (6)], have been solvothermally prepared and structurally characterized. Compounds 1–3 feature 1D [AgPb₂I₇]²⁻ chains built from the condensation of [Ag₂I₆] dimers and [Pb₄I₁₄] tetramers, and compounds 4, 5 and 6 contain similar 1D [CuPb₂Br₇]²⁻ and [AgPb₂Br₇]²⁻ chains, respectively. UV-Vis diffuse reflectance measurements reveal narrow band gaps of 1.75–2.18 eV for compounds 1–6, which lead to efficient and stable photocatalytic degradation activities over organic pollutants under visible light irradiation. Among the title compounds, sample 5 shows the highest photocatalytic degradation activity. The possible mechanism for their stable photocatalytic activities is proposed based on the experimental and theoretical studies.