It is well-known that sluggish surface
charge transfer on a cocatalyst-free
hematite photoanode limits its solar conversion efficiency in photoelectrochemical
(PEC) water splitting. Here, Mo is used as a codopant synergistically
with Sn in α-Fe2O3 to solve this problem.
Besides causing a slight narrowing of bandgap, morphological change,
and even sublimation loss of α-Fe2O3,
Mo doping also imports low-valent Fe due to charge compensation with
MoV/VI as indicated by X-ray photoelectron spectroscopy
and Bader charge computation, which increases the densities of donor
and surfaces states. Although rate law analysis demonstrates slight
retardation of surface reaction kinetics, strongly inhibited charge
recombination in surface states by Mo doping still contributes to
improving the photocurrent density and reducing the onset potential
of α-Fe2O3 and Sn–Fe2O3 photoanodes. An optimized Mo/Sn–Fe2O3 photoanode can realize a low onset potential of 0.68
V vs a reversible hydrogen electrode (VRHE) and a photocurrent
density of 1.97 mA cm–2 at 1.23 VRHE,
enhanced by 58% and 20 times compared to Sn–Fe2O3 and α-Fe2O3, respectively. It
is demonstrated that Mo doping promotes charge transfer which differs
from most traditional n-type dopants that facilitate charge separation
but inhibit charge transfer. This report expands the n-type dopant
family of α-Fe2O3 for efficient PEC water
splitting.
Solid-state electrolyte (SSE) is crucial for a high performance all-solid-state battery. Here, a new solid sodium electrolyte based on the ionic liquid EIMS-NaTFSI and one metal-organic framework (MOF) UiO-67-MIMS functionalized...
In the field of catalysis, nanoreactors with spatially restricted effects play a critical role to enhance the production efficiency of a variety of reactions. In this contribution, we used ZIF-67 nanocubes (size of 140 nm) as a template and conformally deposited Al 2 O 3 thin films by the atomic layer deposition (ALD) technique, wherein Pt nanoparticles (Pt NPs) as active sites were loaded on either the inside or outside of the Al 2 O 3 films. Notably, it was found that the water treatment of the nanoreactors was critical to the enhanced catalytic CO oxidation performance with substantially decreased T 100 (temperature to achieve 100% conversion). Various characterization results indicated the successful synthesis of yolk−shell structured ZIF-67/Pt@ 10Al 2 O 3 -W catalyst with excellent CO oxidation activity and good long-term stability. In addition, in situ diffuse reflectance infrared Fourier transform spectroscopy was used to explore the catalytic oxidation process, and the results revealed that the reason for the superior CO catalytic activity of the designed nanoreactors was ascribed to the moderate CO surface coverage provided by the Al 2 O 3 films and the activated oxygen species. In summary, this work provides some insights into the preparation of metal− organic framework-based nanoreactors using ALD-assisted methods.
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