Two-dimensional (2D) crystalline porous materials with designable structures and high surface areas are currently a hot research topic in the field of proton-and electron-conducting materials, which provide great opportunities to orderly accommodate carriers in available spaces and to accurately understand the conducting path. The 2D dual-conductive inorganic framework) and a Co(II) ion via a hydrothermal method. Due to the presence of a consecutive H-bonding network, electrostatic interactions, and packing effects between the framework and guest molecules, Co 6 Zn 5 W 19 displays a high proton conductivity (3.55 × 10 −4 S cm −1 under 98% RH and 358 K) by a synergistic effect of the combined components. Additionally, a photoactuated electron injection into the semiconducting materials is an important strategy for switching electronic conductivity, because it can efficiently reduce the frameworks without destroying the crystallinity. I−V curves of a tablet of Co 6 Zn 5 W 19 in the reduced and oxidized states yield conductivities of 1.26 × 10 −6 and 5 × 10 −8 S cm −1 , respectively. Moreover, Co 6 Zn 5 W 19 is also successfully applied in the photocatalytic reduction of the toxic Cr(VI) metal ion by utilizing its excellent electronic storage capacity and Baeyer−Villiger (BV) oxidation in a molecular oxygen/aldehyde system.
A powerful approach to generate photocatalysts
for the highly selective
reduction of nitrobenzene using light as the driving force is a combination
of photosensitizers and electron-storable components in a cooperative
photocatalysis fashion. Herein, a new precious metal-free photocatalyst, {ZnW-TPT}, was prepared by incorporating a Zn-substituted
monovacant Keggin polyanion [SiZnW11O39]6– and a photoactive organic bridging link 2,4,6-tri(4-pyridyl)-1,3,5-triazine
(TPT) into a framework. In this structure, the direct coordination
bond between [SiZnW11O39]6– and the TPT ligand and the π–π interactions between
TPT molecules help separate and migrate photogenerated carriers, which
improves the photocatalytic activity of {ZnW-TPT}. The
photoelectrochemical properties of {ZnW-TPT} were well
studied by solid UV–vis absorption, fluorescence, transient
photocurrent response, and electrochemical impedance spectroscopy
tests. {ZnW-TPT} efficiently converts using hydrazine
hydrate with 99% conversion and 99% selectivity for anilines under
mild conditions.
A powerful and promising route for
developing novel photocatalysts
for light-driven toluene oxidation in water under mild conditions
is presented. Herein, a novel polyoxometalate-based metal–organic
framework (POMOF), {Co
4
W
22
-DPNDI}, is prepared
by incorporating the unusual Co4-sandwiched POM anion [Co4(μ-OH)2(SiW11O39)2]10– ({Co
4
W
22
}) and
the photoactive organic bridging link N,N′-bis(4-pyridylmethyl)naphthalene diimide (DPNDI) into a framework. {Co
4
W
22
} is a good candidate for photocatalytic water
oxidation. DPNDI is easily excited to form the radical species DPNDI*
in the presence of an electron donor, which is beneficial for activation
of the inert O2. Anion···π interactions
and covalent bonds between {Co
4
W
22
} and DPNDI
facilitate electron–hole separation and electron transfer. {Co
4
W
22
-DPNDI} displays high catalytic activity for the
activation of the C(sp3)–H bond of toluene using
light as a driving force and inexpensive water as an oxygen source
under mild conditions. In particular, the yield and selectivity are
improved by replacing oxygen with water, which may be ascribed to
the release of protons during the water oxidation process that facilitate
the generation of •OH.
Developing new photocatalysts for sulfide oxidation utilizing in situ-generated 1 O 2 is very significant. Inspired by natural enzymatic processes, we synthesized a mimic sulfite oxidase (SO), {[Co(Mo 4 O 13 )(TPT) 2 ]} (CoMo-TPT), by incorporating an isopolymolybdate anion [Mo 4 O 13 ] 2− into a 2,4,6tri(4-pyridyl)-1,3,5-triazine (TPT)-based metal−organic framework under mild hydrothermal conditions. In this structure, {Mo 4 O 13 } units with intrinsic SO-like catalytic sites are beneficial for the selective oxidation of sulfite and thioether. The ultraviolet−visible spectra of CoMo-TPT exhibited strong absorption from 250 to 650 nm and potential application in the utilization of solar energy. Mott− Schottky measurements indicated that CoMo-TPT is an n-type semiconductor with a LUMO value of −0.70 V (vs NHE) and a HOMO value of 1.39 V. The transient photocurrent responses with strong current density cycles with visible light indicated CoMo-TPT has a high photochemical activity. The lower resistance indicated that CoMo-TPT has a higher efficiency of photoinduced electron and hole separation. CoMo-TPT displayed a high efficiency of 99% and a selectivity of 97.3% in photocatalytic oxidation of sulfides by utilizing in situ-generated 1 O 2 through a tandem process of formation of H 2 O 2 from O 2 followed by catalyzed disproportionation of H 2 O 2 .
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