Pristine
Ru generally shows unsatisfying activity for the electrocatalytic
hydrogen evolution reaction (HER). How to activate its HER activity
through facile methodologies is very challenging. Recently, metal-supported
electrocatalysts integrating metals with efficient hydrogen adsorption
and supports with facile hydrogen desorption delivered a high HER
performance through a metal-to-support hydrogen spillover process,
where the small metal–support work function difference (ΔΦ)
was identified as the criterion for the successful interfacial hydrogen
spillover. Herein, we demonstrate that a hydrogen spillover strategy
significantly boosts the HER activity of Ru by depositing a Ru1Fe1 alloy on CoP (Ru1Fe1/CoP)
with a small ΔΦ of 0.05 eV. Experimentally, Ru1Fe1/CoP (0.7 wt % Ru loading) delivered a high Ru utilization
activity of 139.8 A/mgRu and a long-term durability in
acid. Mechanism investigations authenticated that the small ΔΦ
guaranteed the interfacial hydrogen spillover from Ru1Fe1 with efficient hydrogen adsorption to CoP with facile hydrogen
desorption and thereafter boosted the HER activity of Ru.
Most
oxide semiconductor photoanode materials for water splitting are synthesized
in ambient environment. Oxygen vacancy exists in these samples making
them intrinsically n-type at the as-synthesized state. Oxygen vacancy
has been widely reported for enhancing the performance of a photoanode
by improving the electron conductivity. Besides the effect on the
bulk materials properties, oxygen vacancy also plays an important
role in the interfacial charge transfer to electrolyte, on which much
less attention has been paid in the past. Herein, we found that although
air-annealed W-doped BiVO4 has a higher electron density,
lower surface charge transfer resistance, and a slightly better light
absorption than the O2-annealed sample, the latter displays
a higher photocurrent density. Experimentally we found that the enhanced
performance comes from a better charge separation efficiency, despite
that the presence of oxygen vacancy does lead to a better charge transfer
efficiency. Theoretical calculation finds that there is a localized
state formed inside the bandgap in W-doped BiVO4 with oxygen
vacancy, which serves as recombination center to reduce its charge
separation efficiency. Oxygen vacancy on the V site activates two
different kinds of V into reactive sites for improved surface catalysis.
Oxygen vacancy also facilitates the adsorption of the OHads, Oads, and OOHads involved in a water splitting
process, which benefits the surface catalytic process. It is predicted
from this study that better performance can be achieved by introducing
oxygen vacancy on the surface of a doped BiVO4 and simultaneously
avoiding oxygen vacancy in the bulk. The current study provides an
important understanding of the roles played by oxygen vacancy in doped
photoanode materials.
Carbon neutrality initiative has stimulated the development of the sustainable methodologies for hydrogen generation and safe storage. Aqueous-phase reforming methanol and H2O (APRM) has attracted the particular interests for their high gravimetric density and easy availability. Thus, to efficiently release hydrogen and significantly suppress CO generation at low temperatures without any additives is the sustainable pursuit of APRM. Herein, we demonstrate that the dual-active sites of Pt single-atoms and frustrated Lewis pairs (FLPs) on porous nanorods of CeO2 enable the efficient additive-free H2 generation with a low CO (0.027%) through APRM at 120 °C. Mechanism investigations illustrate that the Pt single-atoms and Lewis acidic sites cooperatively promote the activation of methanol. With the help of a spontaneous water dissociation on FLPs, Pt single-atoms exhibit a significantly improved reforming of *CO to promote H2 production and suppress CO generation. This finding provides a promising path towards the flexible hydrogen utilizations.
The effect of oxygen vacancies (V
O
) on α-Fe
2
O
3
(110) facet on the
performance of photoelectrochemical (PEC) water splitting is researched
by both experiments and density functional theory (DFT) calculations.
The experimental results manifest that the enhancement in photocurrent
density by the presence of V
O
is related with increased
charge separation and charge-transfer efficiencies. The electrochemical
analysis reveals that the sample with V
O
demonstrates an
enhanced carrier density and reduced charge-transfer resistance. The
results of DFT calculation indicate that the better charge separation
is also contributed by the decrease of potential on the V
O
surface, which improves the hole transport from the bulk to the
surface. The reduced charge-transfer resistance is owing to the greatly
increased number of active sites. The current study provides important
insight into the roles of V
O
on α-Fe
2
O
3
photoanode, especially on its surface catalysis. The generated
lesson is also helpful for the improvement of other PEC photoanode
materials.
Hydrogen
spillover-based binary (HSBB) catalysts have attracted
more and more attention in recent years because of their unique reaction
mechanism, different from traditional single-component catalysts.
In this paper, using density functional theory for the screening of
materials, we find 11 candidates with excellent hydrogen evolution
reaction (HER) performance under acidic conditions. Among them, Pt1Ir1-MoS2 has been successfully synthesized
and verified through experiment to have exhibited the outstanding
catalytic performance as predicted. Detailed analysis of these HSBB
catalysts reveals the key role of hydrogen spillover toward efficient
water splitting, paving the way for the discovery of widely applicable
materials and a feedback loop that delivers materials as designed.
Greatly increasing the number of known HSBB catalysts, the current
study not only demonstrates the accuracy of our screening of materials
but also provides a novel paradigm for accelerating the development
of materials and reducing costs.
Despite the recent advances in enhancing the durability and reducing the overpotential of ruthenium (Ru)-based electrocatalysts for acidic oxygen evolution reaction (OER), their stability hardly meets the requirement of practical...
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