Hydrazine-Assisted Synthesis, Structures, Photoelectricity, and Photocatalysis of Ternary Mercury-Tellurostannate Hybrids with Transition-Metal Complexes

Tellurostannates are traditionally prepared by multistep reactions using the tellurides SnTe, SnTe2, K4SnTe4, or A6SnTe6 (A = K, Rb, or Cs) as precursors, which are usually prepared by the molten reaction of alkali metals Sn and Te under harsh synthetic conditions. Differently, ternary Hg-tellurostannate hybrids [Mn(en)3]HgSnTe3(Te2) (1) (en = ethylenediamine), [Mn(dien)2]HgSnTe3(Te2) (2), and [Fe(dien)2]HgSnTe3(Te2) (3) (dien = diethylenetriamine) were synthesized by one-pot reactions using Sn and Te powders as starting materials in the presence of hydrazine under mild solvothermal conditions. In 1, HgTe3 and SnTe4 units are joined via Te-sharing to form a 1-D polymeric chain [HgSnTe3(Te2)]n2n-, while the [HgSnTe3(Te2)]n2n- chains in 2 and 3 are composed of HgTe4 and SnTe4 units. The common feature of the [HgSnTe3(Te2)2-]n chains in 1-3 is that they are constructed by both the telluride anion Te2- and the polytelluride anion Te22-. 1-3 exhibited strong photocurrent responses with current densities of 5.26, 3.38, and 3.94 μA cm-2, respectively. They showed effective photocatalytic activities for methylene blue degradation with degradation ratios in the range of 85.3-94.6% after light irradiation for 80 min. Investigation of the photocatalytic mechanism showed that •O2- radicals and h+ holes were the main active substances in the photodegradation.

Syntheses, crystal structure, and photoelectric properties of two Zn-based chalcogenidoantimonates Zn-Sb-Q (Q = S, Se)

Metal chalcogenides are a special class of semiconducting materials characterized by their rich structures and compositions, making them a promising option for a broad range of applications in the field of inorganic chemistry. However, the path forward is not without its challenges, notably in the realms of interface management and enhancing carrier concentration. To address these issues, we solvothermally synthesized two novel chalcogenidoantimonates [Zn(tren)]2Sb2Se5 (1) [tren = tris (2-aminoethyl) amine] and [Zn(tepa)H]2Sb2S6 (2) (tepa = tetraethylenepentamine) utilizing transition metal Zn by band gap optimization strategy in the visible region. Both compounds exhibited distinct zero-dimensional cluster structures, with transition metal complex cations acting as structure-directing agents. A comprehensive analysis of the electronic structure, band gap, and photocurrent response of these crystals was undertaken, revealing significantly enhanced photocatalytic properties compared to preceding studies. This research underscores the potential of antimony chalcogenides in the realm of photoelectric properties and promotes the applications of chalcogenides.

Strong Photocurrent Response of Selenoarsenates With Different Transition Metal Complexes as Structure-Directing Agents

Four selenoarsenates with different transition-metal complexes [Co(tren)₂H]AsSe₄ [tren = tris(2-aminoethyl)amine] (1); [Ni₂(dien)₄](As₂Se₅) (dien = diethylenetriamine) (2); [Zn(tren)]₂(As₂Se₅) (3) and [Mn(tren)]₂(As₂Se₅) (4) were solvothermally synthesized in a mixed solvent of organic amine and alcohol solution. The compounds 1-4 have pyramidal/tetrahedral structures (AsSe₃/AsSe₄), and contain transition metal (Co²⁺, Ni²⁺, Zn²⁺ and Mn²⁺) complex that form distinct zero-dimensional (0-D) clusters. Arsenic atoms form a tetrahedron in compounds 1 and 2; 1 consists of discrete tetrahedral (AsSe₄) and transition metal complex [Co(tren)₂]²⁺; 2 is composed of an anion [As₂Se₅]^4- cluster and transition metal complex [Ni(dien)₂]²⁺. In compounds 3 and 4, arsenic atom forms a pyramidal AsSe₃ and the two pyramidal AsSe₃ share a corner connection to form a dimer [As₂Se₅]^4-; 3 is characterized as a cluster consisting of two unsaturated [Zn(tren)]²⁺ caiton linked by a dimer (As₂Se₅)^4- linkage; in 4, unsaturated [Mn(tren)]²⁺ caiton is linked to two trigonal-bipyramidal [Mn(tren)]Se via dimer (As₂Se₅)^4- to form [Mn(tren)]₄[As₄Se₁₀] cluster. To our knowledge, [Zn(tren)]₂(As₂Se₅) (3) is the first zinc selenoarsenate containing the (As₂Se₅)^4- anion type. Furthermore, the Mn²⁺ ions adopt a trigonal-biyramidal (five-coordinate) and octahedral (six-coordinate) environment. Adding K₂CO₃/Cs₂CO₃ to the synthesis system is necessary and may act as a mineralizer. Several properties of compounds 1-4 have been characterized in our studies, in particular their strong photocurrent response characteristics under visible light irradiation.