A controllable vacuum-diffusion method for gradual phosphidation of carbon coated metallic Co nanoparticles into Co/CoP Janus nanoparticles is reported. Janus Co/CoP nanoparticles, as typical Mott-Schottky electrocatalysts, exhibit excellent hydrogen evolution reaction and oxygen evolution reaction performance in various electrolytes across wide pH range along with high durability. The Mott-Schottky Co/CoP catalyst can work as bifunctional electrode materials for overall water splitting in wide pH range and can achieve a current density of 10 mA cm −2 in neutral electrolyte at only 1.51 V.
Heterogeneous
catalysts of inexpensive and reusable transition-metal
are attractive alternatives to homogeneous catalysts; the relatively
low activity of transition-metal nanoparticles has become the main
hurdle for their practical applications. Here, the de novo design of a Mott–Schottky-type heterogeneous catalyst is
reported to boost the activity of a transition-metal nanocatalyst
through electron transfer at the metal/nitrogen-doped carbon interface.
The Mott–Schottky catalyst of nitrogen-rich carbon-coated cobalt
nanoparticles (Co@NC) was prepared through direct polycondensation
of simple organic molecules and inorganic metal salts in the presence
of g-C3N4 powder. The Co@NC with controllable
nitrogen content and thus tunable Fermi energy and catalytic activity
exhibited a high turnover frequency (TOF) value (8.12 mol methyl benzoate
mol–1 Co h–1) for the direct,
base-free, aerobic oxidation of benzyl alcohols to methyl benzoate;
this TOF is 30-fold higher than those of the state-of-the-art transition-metal-based
nanocatalysts reported in the literature. The presented efficient
Mott–Schottky catalyst can trigger the synthesis of a series
of alkyl esters and even diesters in high yields.
The traditional NH3 production
method (Haber–Bosch
process) is currently complemented by electrochemical synthesis at
ambient conditions, but the rather low selectivity (as indicated by
the Faradaic efficiency) for the electrochemical reduction of molecular
N2 into NH3 impedes the progress. Here, we present
a powerful method to significantly boost the Faradaic efficiency of
Au electrocatalysts to 67.8% for the nitrogen reduction reaction (NRR)
by increasing their electron density through the construction of inorganic
donor–acceptor couples of Ni and Au nanoparticles. The unique
role of the electron-rich Au centers in facilitating the fixation
and activation of N2 was also investigated via theoretical
simulation methods and then confirmed by experimental results. The
highly coupled Au and Ni nanoparticles supported on nitrogen-doped
carbon are stable for reuse and long-term performance of the NRR,
making the electrochemical process more sustainable for practical
application.
Exploring high-performance zeolite-supported metal catalysts is of great significance. Herein, we develop a strategy for fabricating isolated single metal atomic site catalysts in Y zeolite (M-ISAS@Y, M = Pt, Pd, Ru, Rh, Co, Ni, Cu) by in situ separating and confining a metal−ethanediamine complex into β-cages during the crystallization process followed by thermal treatment. The M-ISAS are stabilized by skeletal oxygens of Y zeolite, and the crystallinity, porosity, and large surface area are well inherited in M-ISAS@ Y. As a demonstration, acidic Pt-ISAS@Y is used for n-hexane isomerization involving consecutive catalytic dehydrogenation/hydrogenation on Pt-ISAS and isomerization on Brønsted acid sites. The turnover frequency value of Pt-ISAS reaches 727 h −1 , 5 times more than Pt nanoparticles (∼3.5 nm), with a total isomer selectivity of more than 98%. This strategy provides a convenient route to fabricate promising zeolite-based M-ISAS catalysts for industrial applications.
Engineering the adsorption of molecules on active sites is an integral and challenging part for the design of highly efficient transition-metal-based catalysts for methanol dehydrogenation. A Mott-Schottky catalyst composed of Ni nanoparticles and tailorable nitrogen-doped carbon-foam (Ni/NCF) and thus tunable adsorption energy is presented for highly efficient and selective dehydrogenation of gas-phase methanol to hydrogen and CO even under relatively high weight hourly space velocities (WHSV). Both theoretical and experimental results reveal the key role of the rectifying contact at the Ni/NCF boundaries in tailoring the electron density of Ni species and enhancing the absorption energies of methanol molecules, which leads to a remarkably high turnover frequency (TOF) value (356 mol methanol mol Ni h at 350 °C), outpacing previously reported bench-marked transition-metal catalysts 10-fold.
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