A passivation layer plays an important role in suppressing charge recombination on surface trap states. However, the effect of a single passivation layer is limited. Building a passivation system containing multiple passivation layers with different functions for efficient charge separation presents a challenge. In this study, we demonstrate the synergistic passivation effect between a metal−organic framework-derived TiO 2 nanoparticle layer and an ultrathin carbon layer, which facilitates the charge separation of an α-Fe 2 O 3 photoanode with a surface separation efficiency of 57%. The α-Fe 2 O 3 /TiO 2 /C photoanode generates a photocurrent of 1.93 mA cm −2 at 1.23 V vs a reversible hydrogen electrode, which is about 3.22 times higher than that of pristine α-Fe 2 O 3 . After the introduction of the cocatalyst β-FeOOH onto the α-Fe 2 O 3 /TiO 2 /C photoanode, a higher photocurrent of 2.95 mA cm −2 is generated under the same condition without doping and constructing a heterojunction.
The high-performance optical thermometer probes are of
great significance
in diverse areas; lanthanide metal–organic frameworks (Ln-MOFs)
are a promising candidate for luminescence temperature sensing owing
to their unique luminescence properties. However, Ln-MOFs have poor
maneuverability and stability in complex environments due to the crystallization
properties, which then hinder their application scope. In this work,
the Tb-MOFs@TGIC composite was successfully prepared using simple
covalent crosslinking through uncoordinated −NH2 or COOH on Tb-MOFs reacting with the epoxy groups on TGIC {Tb-MOFs
= [Tb2(atpt)3(phen)2(H2O)]
n
; H2atpt = 2-aminoterephthalic
acid; phen = 1,10-phenanthroline monohydrate}. After curing, the fluorescence
properties, quantum yield, lifetime, and thermal stability of Tb-MOFs@TGIC
were remarkably enhanced. Meanwhile, the obtained Tb-MOFs@TGIC composites
exhibit excellent temperature sensing properties in the low-temperature
(S
r = 6.17% K–1 at 237
K), physiological temperature (S
r = 4.86%
K–1 at 323 K), or high-temperature range (S
r = 3.88% K–1 at 393 K) with
high sensitivity. In the temperature sensing process, the sensing
mode of single emission changed into double emission for ratiometric
thermometry owing to the back energy transfer (BenT) from Tb-MOFs
to TGIC linkers, and the BenT process enhanced with the increase of
temperature, which further improved the accuracy and sensitivity of
temperature sensing. Most notably, the temperature-sensing Tb-MOFs@TGIC
can be easily coated on the surface of polyimide (PI), glass plate,
silicon pellet (SI), and poly(tetrafluoroethylene) plate (PTFE) substrates
by a simple spraying method, which also exhibited an excellent sensing
property, making it applicable for a wider T range
measurement. This is the first example of a postsynthetic Ln-MOF hybrid
thermometer operative over a wide temperature range including the
physiological and high temperature based on back energy transfer.
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