Discrete Supertetrahedral T5 Selenide Clusters and Their Se/S Solid Solutions: Ionic-Liquid-Assisted Precursor Route Syntheses and Photocatalytic Properties

Graphical Fine tweaking . Six heterometallic T5 selenides and their Se/S solid solutions M-In-Q (M=Cu or Cd; Q=Se or Se/S) have been solvothermally synthesized by a two-step method. The T5 selenide clusters, the largest supertetrahedral T n clusters reported to date, show photocatalytic activity that can be tuned according to their constituent components. Although supertetrahedral T n sulfide clusters ( n= 2–6) have been extensively explored, the synthesis of T n selenide clusters with n >4 has not been achieved thus far. Reported here are ionic-liquid (IL)-assisted precursor route syntheses, characterizations, and the photocatalytic properties of six new M-In-Q (M=Cu or Cd; Q=Se or Se/S) chalcogenide compounds, namely [Bmmim] 12 Cu 5 In 30 Q 52 Cl 3 (Im) (Q=Se ( T5-1 ), Se 48.5 S 3.5 ( T5-2 ); Bmmim=1-butyl-2,3-dimethylimidazolium, Im=imidazole), [Bmmim] 11 Cd 6 In 28 Q 52 Cl 3 (MIm) (Q=Se ( T5-3 ), Se 28.5 S 23.5 ( T5-4 ), Se 16 S 36 ( T5-5 ); MIm=1-methylimidazole), and [Bmmim] 9 Cd 6 In 28 Se 8 S 44 Cl(MIm) 3 ( T5-6 ). The cluster compounds T5-1 and T5-3 represent the largest molecular supertetrahedral T n selenide clusters to date. Under visible-light illumination, the Cu-In-Q compounds showed photocatalytic activity towards the decomposition of crystal violet, whereas the Cd-In-Q compounds exhibited good photocatalytic H 2 evolution activity. Interestingly, the experimental results show that the photocatalytic performances of the selenide/sulfide solid solutions were significantly better than those of their selenide analogues, for example, the degradation time of the organic dye with T5-2 was much shorter than that with T5-1 , whereas the photocatalytic H 2 evolution efficiencies with T5-3 – T5-6 improved significantly with increasing sulfur content. This work highlights the significance of IL-assisted precursor route synthesis and the tuning of photocatalytic properties through the formation of solid solutions.