A series of simple phenothiazine-based dyes have been synthesized, in which a cyanoacrylate acceptor directly attached to the C(3) position of phenothiazine, and an additional linear electron-rich (4-hexyloxy)phenyl group at C(7) on the opposite side of the acceptor, and an alkyl chain with different length at N(10) of the phenothiazine periphery are presented. The dye molecules have a linear shape which is favorable for the formation of a compact dye layer on the TiO 2 surface, while their butterfly conformations can sufficiently inhibit molecular aggregation. Moreover, the structural features of (4-hexyloxy)phenyl donor moiety at the C(7) position of phenothiazine extends the π-conjugation of the chromophore, thus enhancing the performance of dye-sensitized solar cells (DSSCs). Moreover, the alkyl substituents with different chain length at the N(10) atom of phenothiazine could further optimize the performance through completely shielding the surface of TiO 2 from the I − /I 3electrolyte and subsequently reducing the leakage of dark current. Under simulated AM 1.5G irradiation, the PT-C6 based DSSC produces a short-circuit photocurrent of 15.32 mA cm −2 , an open-circuit photovoltage of 0.78 V, a fill factor of 0.69, corresponding to a power conversion efficiency (PCE) of 8.18%, which exceeds the reference N719 (7.73%) under identical fabrication conditions. Notably, the designed molecular structure represents the highest photovoltaic conversion efficiency value when compared with other reported phenothiazine-derived dyes.
Development
of water-stable metal–organic frameworks (MOFs)
for promising visible-light-driven photocatalytic water splitting
is highly desirable but still challenging. Here we report a novel
p-type nickel-based MOF single crystal (Ni-TBAPy-SC) and its exfoliated
nanobelts (Ni-TBAPy-NB) that can bear a wide range of pH environment
in aqueous solution. Both experimental and theoretical results indicate
a feasible electron transfer from the H4TBAPy ligand (light-harvesting
center) to the Ni–O cluster node (catalytic center), on which
water splitting to produce hydrogen can be efficiently driven free
of cocatalyst. Compared to the single crystal, the exfoliated two-dimensional
(2D) nanobelts show more efficient charge separation due to its shortened
charge transfer distance and remarkably enhanced active surface areas,
resulting in 164 times of promoted water reduction activity. The optimal
H2 evolution rate on the nanobelt reaches 98 μmol
h–1 (ca. 5 mmol h–1 g–1) showing benchmarked apparent quantum efficiency (AQE) of 8.0% at
420 nm among water-stable MOFs photocatalysts.
Running rings around mercuric ions: A [26]hexaphyrin(1.1.1.1.1.0), comprising an α,α′‐bipyrrole unit and four pyrrolic and five pentafluorophenyl rings, was prepared and characterized by X‐ray crystallography (see picture; N blue, F green, C black). The expanded porphyrin displays near‐infrared luminescence above 900 nm and may serve as a highly sensitive and selective chemodosimeter for Hg2+ ions.
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