The confirmation and regulation of active sites are particularly critical for the design of methanol oxidation reaction (MOR) catalysts. Here, an acid etching method for facet control combined with defect construction was utilized to synthesize Co 3 O 4 nanoparticles on nickel foam for preferentially exposing the (311) facet with enriched oxygen vacancies (V O ). The acid-leached oxides exhibited superior MOR activity with a mass activity of 710.94 mA mg −1 and an area-specific activity of 3.390 mA cm −2 as a result of (i) abundant active sites for MOR promoted by V O along with the highly active (311) facet being exposed and (ii) phase purification-reduced adsorption energy (E ads ) of methanol molecules. Ex situ X-ray photoelectron spectroscopy proved that highly active CoOOH obtained via the activation of plentiful Co 2+ effectively improved the MOR. Density functional theory calculations confirmed that the selective exposed (311) facet has the lowest E ads for CH 3 OH molecules. This work puts forward acid etching as the facet modification and defect engineer for nanostructured non-noble catalysts, which is expected to result in superior electrochemical performance required for advanced alkaline direct methanol fuel cells.
Regulating
the electronic structure of MoS2 by constructing
cationic vacancies is an effective method to activate and improve
its intrinsic properties. Herein, we synthesize the MoS2-based composite with abundant single atomic Mo cation vacancies
through uniformly loading nickel–cobalt–Prussian blue
analogues (NiCoPBA) (NiCoPBA–MoS2–VMo) by immersing a single Ni atom-decorated MoS2 (Ni–MoS2) into K3[Co(CN)6] solution. Subsequently,
NiCoP–MoS2–VMo with improved conductivity
is obtained by phosphating the composite as a high-efficiency hydrogen
evolution reaction (HER) catalyst. Experiments and theoretical calculations
indicate that the electrons of NiCoP are spontaneously transferred
to the substrate MoS2–VMo nanosheets
in NiCoP–MoS2–VMo, and the moderately
oxidized NiCoP is beneficial to the adsorption of OH*. Meanwhile,
the mono-atomic Mo cation vacancies of the catalyst modulate the electronic
structure of S, optimizing the adsorption of hydrogen in the reaction
process. Therefore, NiCoP–MoS2–VMo has enhanced chemical adsorption for H* (on MoS2–VMo) and OH*(on NiCoP), expediting the water-splitting step
and HER catalysis, and benefiting from the regulation of the electronic
structure induced by the construction of metallic Mo vacancies in
MoS2, the as-prepared catalyst displays an overpotential
of only 67 mV at 10 mA cm–2 with long-term stability
(no current decay over 20 h). This work affords not only a kind of
efficient HER catalysts but also a new valuable route for developing
inexpensive and high-performance catalysts with single atomic cation
vacancies.
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