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.
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.
Designing molecular photocatalysts
for potent photochemical reactivities
ranks among the most challenging but rewarding endeavors in synthetic
photochemistry. Herein, we document a quinoline-based organophotoredox
catalyst, 2,4-bis(4-methoxyphenyl)quinoline (DPQN2,4‑di‑OMe
), that could be assembled via the facile
aldehyde–alkyne–amine (A3) couplings. Unlike
the reported photocatalysts, which impart their photoreactivities
as covalently linked entities, our mechanistic studies suggested a
distinct proton activation mode of DPQN2,4‑di‑OMe
. Simply upon protonation, DPQN2,4‑di‑OMe
could reach a highly oxidizing excited state under visible-light
irradiation (E*1/2 = +1.96 V vs a standard calomel electrode, SCE). On this basis, the synergistic
merger of DPQN2,4‑di‑OMe
and
cobaloxime formulated an oxidative cross-coupling platform, enabling
the Minisci alkylation and various C–C bond-forming reactions
with a diverse pool of radical precursors in the absence of chemical
oxidants. The catalytic loading of DPQN2,4‑di‑OMe
could be minimized to 0.025 mol % (TON = 3360), and a polymer-supported
photocatalyst, DPQN2,4-di-OR@PS, was prepared
to facilitate catalyst recycling (at a 0.50 mmol % loading and up
to five times without significant loss of photosynthetic efficiency).
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−1 Ni h−1 at 350 °C), outpacing previously reported bench‐marked transition‐metal catalysts 10‐fold.
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