UiO-66-X (X = H, NH2, NO2, Br) have been successfully synthesized and tested for their photocatalytic activity in water treatment. Results show that electronic effect of the ligand substituents greatly affects the photocatalytic activity of UiO-66. The rates obtained by different substituents are linearly correlated with their Hammett coefficients.

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The discrete supertetrahedral chalcogenido Tn clusters can be regarded as a type of quantum dot (QD) with precise structure and uniform size. They were commonly studied in the solid state because of their poor solubility or highly negative charge that leads to instability in common solvents. These drawbacks limit their potential applications as efficient photocatalysts. Herein we first obtained a sulfide compound via an ionic-liquid-assisted precursor method, namely, (BMMim)9(Cd3In17S31Cl4) (T4-1, BMMim = 1-butyl-2,3-dimethylimidazolium). T4-1 is characteristic of the discrete anionic T4 cluster and is insoluble in common solvents. Introducing Se into the structure resulted in compounds (BMMim)9(Cd3In17S13Se18Cl4) (T4-2) and (BMMim)9(Cd3In17Se31Cl4)­(4,4′-bpy) (T4-3) with narrower band gaps. Moreover, T4-2 and T4-3 were soluble in dimethyl sulfoxide (DMSO) probably because of weaker interactions between cations and anions than in T4-1. The solution stability of these clusters has been confirmed by mass spectrometry. Further characterization reveals that the highly dispersed T4 clusters exposed more active sites in solution, so their rates of relevant H2 production were improved to be ∼5 times that in the solid state. To our knowledge, this is the first time that highly dispersed Tn clusters have been applied in photocatalytic H2 generation.

Two novel two‐dimensional metal–organic frameworks (2D MOFs), 2D‐M2TCPE (M=Co or Ni, TCPE=1,1,2,2‐tetra(4‐carboxylphenyl)ethylene), which are composed of staggered (4,4)‐grid layers based on paddlewheel‐shaped dimers, serve as heterogeneous photocatalysts for efficient reduction of CO2 to CO. During the visible‐light‐driven catalysis, these structures undergo in situ exfoliation to form nanosheets, which exhibit excellent stability and improved catalytic activity. The exfoliated 2D‐M2TCPE nanosheets display a high CO evolution rate of 4174 μmol g−1 h−1 and high selectivity of 97.3 % for M=Co and Ni, and thus are superior to most reported MOFs. The performance differences and photocatalytic mechanisms have been studied with theoretical calculations and photoelectric experiments. This study provides new insight for the controllable synthesis of effective crystalline photocatalysts based on structural and morphological coregulation.