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)]AgPbI [TM = Ni (1), Co (2) and Zn (3)], [Co(2,2'-bipy)]CuPbBr (4) and [TM(2,2'-bipy)]AgPbBr [TM = Ni (5) and Fe (6)], have been solvothermally prepared and structurally characterized. Compounds 1-3 feature 1D [AgPbI] chains built from the condensation of [AgI] dimers and [PbI] tetramers, and compounds 4, 5 and 6 contain similar 1D [CuPbBr] and [AgPbBr] 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.

Transition-Metal-Complex-Directed Synthesis of Hybrid Iodoargentates with Single-Crystal to Single-Crystal Structural Transformation and Photocatalytic Properties

“…Compound 4 crystallized in the monoclinic P 2 1 / m space group system. Although compound 4 had the same chemical formula of [Ag 3 I 5 ] as [Co­(phen) 3 ]­(Ag 3 I 5 )·2CH 3 CN, [Co­(2,2-bipy) 3 ]­Ag 3 I 5 , and {[(Hpy) 2 ·H 2 O]­[Ag 3 I 5 ]} n , the basic structural unit of compound 4 was a [Ag 6 I 10 ] 4– discrete anion (Figure b), which was built up from five AgI 4 tetrahedra and one AgI 3 triangle via edge/face sharing. The I–Ag–I bond angles of 93.14(6)–123.86(7)° and the Ag–I bond lengths of 2.6498(19)–3.022(2) Å were consistent with those of compound 1 (Table S6).…”

“…Therefore, the introduction of TM complex cations can improve the photoelectronic properties of hybrid iodoargentates, and great efforts have been put into the synthesis of functional hybrid iodoargentates such as the TM-complex-containing iodoargentates (Table S1). ,,,− However, the controlled synthesis of hybrid iodoargentates remains a challenge because of the influence of external stimuli (e.g., reaction temperature, solvent, and pH value) upon the structures and dimensions of iodoargentates during the crystallization process. ,− In spite of the synthesis and structural characterization of numerous hybrid iodoargentates, systematic research on these external factors has not been explored. Recent research has demonstrated that it is easy to obtain low-dimensional iodoargentates at a lower temperature (Table S1).…”

Syntheses, Crystal Structures, and Photocatalytic Properties of Bromoargentates Induced by Transition‐Metal–phen Complex Cations

“…Investigation into the photocatalytic mechanism of TM‐containing haloargentates has shown that photoinduced charge transition mainly occurs between the haloargentate anions and the TM complex cations under visible‐light irradiation. [4c], [4b], , The resulting photogenerated electrons are captured by O 2 in the solution to form a superoxide ion · O 2– , which is attributed to the oxidation of the organic dyes. Moreover, the remaining photogenerated holes can be transferred to oxidize the X – ion to X 0 , which oxidizes the organic dye molecules and becomes reduced to the X – ion again in the catalytic reaction.…”

“…Moreover, the remaining photogenerated holes can be transferred to oxidize the X – ion to X 0 , which oxidizes the organic dye molecules and becomes reduced to the X – ion again in the catalytic reaction. [4c], , , The closed 3D structures of the bromoargentate anions in 1 – 3 prevent effective use of the reactive sites of X 0 on the anions owing to steric hindrance of the organic dye molecules. As a result, 1 – 3 are less effective than compounds 4 and 6 with opened structures of the bromoargentate anions.…”

Solvated Lanthanide Cationic Template Strategy for Constructing Iodoargentates with Photoluminescence and White Light Emission

“…Commonly, there are three kinds of templates according to their intrinsic nature. The organic template, especially organoamines, is the most famous one, and the intensively studied halometallates bearing a perovskite structure which have witnessed extraordinary breakthroughs in photovoltaics are representative of such compounds. − The inorganic template is another one, such as alkali metals, through which various iodometallates have been successfully synthesized. , The third one, called the organic–inorganic hybrid, has been well demonstrated by the in situ generated metal–organic complexes to direct the assembly. − For instance, two iodoargentates, M­(en) 3 Ag 2 I 4 (M = Mn 2+ and Mg 2+ ; en = ethylenediamine), were prepared by Ren’s group, in which the structures could be subtly modulated by metal coordination cations . Generally speaking, the effectiveness of these kinds of templates to fabricate iodometallates has been confirmed in recent publications.…”