The
instability and low inferior catalytic activity of metal-halide
perovskite nanocrystals are crucial issues for promoting their practical
application in the photocatalytic field. Herein, we in situ coat a
thin graphdiyne (GDY) layer on CsPbBr3 nanocrystals based
on a facile microwave synthesis method, and employ it as a photocatalyst
for CO2 reduction. Under the protection of GDY, the CsPbBr3-based photocatalyst delivers significantly improved stability
in a photocatalytic system containing water concomitant with enhanced
CO2 uptake capacity. The favorable energy offset and close
contact between CsPbBr3 and GDY trigger swift photogenerated
electron transfer from CsPbBr3 to doping metal sites in
GDY, boosting a remarkable improvement in the photocatalytic performance
for CO2 reduction. Without adding traditional sacrificial
reductants, the cobalt-doped photocatalyst achieves a high yield of
27.7 μmol g–1 h–1 for photocatalytic
CO2 conversion to CO based on water as a desirable electron
source, which is about 8 times higher than that of pristine CsPbBr3 nanocrystals.
The judicious design of efficient electron mediators to accelerate the interfacial charge transfer in a Z‐scheme system is one of the viable strategies to improve the performance of photocatalysts for artificial photosynthesis. Herein, ultrathin and small‐size graphene oxide (USGO) nanosheets are constructed and employed as the electron mediator to elaborately exploit an efficient CsPbBr3‐based all‐solid‐state Z‐scheme system in combination with α‐Fe2O3 for visible‐light‐driven CO2 reduction with water as the electron source. CsPbBr3 and α‐Fe2O3 can be closely anchored on USGO nanosheets, owing to the existence of interfacial strong chemical bonding behaviors, which can significantly accelerate the photogenerated carrier transfer between CsPbBr3 and α‐Fe2O3. The resultant improved charge separation efficiency endows the Z‐scheme system exhibiting a record‐high electron consumption rate of 147.6 µmol g−1 h−1 for photocatalytic CO2‐to‐CO conversion concomitant with stoichiometric O2 from water oxidation, which is over 19 and 12 times higher than that of pristine CsPbBr3 nanocrystals and the mixture of CsPbBr3 and α‐Fe2O3, respectively. This work provides a novel and effective strategy for improving the catalytic activity of halide‐perovskite‐based photocatalysts, promoting their practical applications in the field of artificial photosynthesis.
We have firstly demonstrated the photocatalytic utilization of a halide perovskite for combining reduction of CO2 with selective oxidation of methanol.
In this study, a new TiO2-based photocatalyst
with both
B doping and Bi2O3 coupling (Bi2O3/TiO2–x
B
x
) was synthesized to degrade pentachlorophenol under visible
light (λ > 420 nm) irradiation. The resulting Bi2O3/TiO2–x
B
x
sample exhibited much higher photocatalytic performance
than the counterparts with only B doping or Bi2O3 coupling or pure TiO2. This is because B doping could
result in more visible light absorption to produce more photogenerated
electron–hole pairs, while Bi2O3 coupling
could favor the separation and transfer of photoinduced charge carriers
to inhibit their recombination. We interestingly found that the visible
light-driven degradation of pentachlorophenol was mainly attributed
to photogenerated holes and ·O2
– other than ·OH as reported previously because the hybridization
of B 2p orbital and O 2p orbital could elevate the VB edge of Bi2O3/TiO2–x
B
x
as compared to that of pure TiO2 and thus lower the oxidation ability of photogenerated holes, blocking
the pathway of photogenerated holes induced oxidation of surface OH– and water to generate ·OH. The intermediates
during the PCP photodegradation were systematically analyzed, ruling
out the existence of high toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. These results reveal
that the visible light-driven photocatalytic degradation of PCP over
Bi2O3/TiO2–x
B
x
is an effective and green method to
remove highly toxic halogenated aromatic compounds.
Capping ligands are indispensable for the preparation of metal‐halide‐perovskite (MHP) nanocrystals (NCs) with good stability; however, the long alkyl‐chain capping ligands in conventional MHP NCs will be unfavorable for CO2 adsorption and hinder the efficient carrier separation on the surface of MHP NCs, leading to inferior catalytic activity in artificial photosynthesis. Herein, CsPbBr3 nanocrystals with short‐chain glycine as ligand are constructed through a facile ligand‐exchange strategy. Owing to the reduced hindrance of glycine and the presence of the amine group in glycine, the photogenerated carrier separation and CO2 uptake capacity are noticeably improved without compromising the stability of the MHP NCs. The CsPbBr3 nanocrystals with glycine ligands exhibit a significantly increased yield of 27.7 μmol g−1 h−1 for photocatalytic CO2‐to‐CO conversion without any organic sacrificial reagents, which is over five times higher than that of control CsPbBr3 NCs with conventional long alkyl‐chain capping ligands.
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