A bubble-releasing
assisted pulse electrodeposition method was
developed to create metallic alloy, NiFe, nanotube arrays in one step.
The NiFe alloy nanotube array exhibited excellent bifunctional electrolytic
activities, achieving low overpotentials of 100 mV for the hydrogen
evolution reaction and 236 mV for the oxygen evolution reaction at
10 mA cm–2, both in 1 M KOH at room temperature.
For overall water splitting, the NiFe alloy nanotube array delivered
10 mA cm–2 at an ultralow cell voltage of 1.58 V,
among the top tier of the state-of-the-art bifunctional electrocatalysts.
The NiFe alloy nanotube array also exhibited ultrastability at high
current densities, experiencing only a minor chronoamperometric decay
of 6.5% after a 24 h operation at 400 mA cm–2. The
success of the present binder-free nanotube array-based electrode
can be attributed to the much enlarged reaction surface area, one-dimensionally
guided charge transport and mass transfer offered by the nanotube
structure, and improved product crystallinity provided by the pulse
current electrodeposition. The nanotube array structure proves to
be a promising new architecture design for electrocatalysts.
Syngas,
consisting of equimolar CO and H2, is an important feedstock for large-scale production of a wide range of commodity chemicals including aldehyde,
methanol, ammonia, and other oxygenated chemicals. Dry reforming of
methane (DRM), proceeding by reacting greenhouse gases, CO2 and CH4, at high temperatures in the presence of a metal
catalyst, is considered one of the most environmentally friendly routes
for syngas production. Nevertheless, nonprecious metal-based catalysts,
which can operate at relatively low temperatures for high product
yields and selectivities, are required to drive the DRM process for
industrial applications effectively. Here, we developed NiCo@C nanocomposites
from a corresponding NiCo-based bimetallic metal–organic framework
(MOF) to serve as high-performance catalysts for the DRM process,
achieving high turnover frequencies (TOF) at low temperatures (>5.7
s–1 at 600 °C) and high product selectivities
(H2/CO = 0.9 at 700 °C). The incorporation of Co in
Ni catalysts improves the operation stability and light-off stability.
The present development for MOF-derived nanocomposites opens a new
horizon for design of DRM catalysts.
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