We developed a novel methodology for the general synthesis of non-precious transition metal–nitrogen–carbon electrocatalysts based on formamide condensation.
Electrochemical CO2 reduction reaction (CO2RR) is a promising approach
for conversion of CO2 to value-added chemicals. In this
contribution, we demonstrated an electrode design strategy via wettability
control and fabricated a freestanding three-dimensional electrode.
This electrode design strategy created more three-phase (solid–liquid–gas)
contacts due to the sufficient amount of CO2 gas bubbles
attached to the surface of the electrode under catalytic turnover
conditions and the ongoing change of electrolyte wetting, and replacement
of electrolyte by the gas bubble promotes the activity of CO2RR. This work exploits a new way that sheds light on electrode design
for underwater gas-consumption electrocatalytic applications.
As a significant part in optical computation, analogue optical spatial/temporal differentiators could play a great role in all‐optical signal processing, feature extraction, and optical storage. In the past few years, they have experienced rapid development but mostly for a single function. For many scenarios, optical computation with integrated functionalities is highly desired. In this work, an analogue optical spatiotemporal differentiator utilizing all‐dielectric multilayer is proposed. The film stack is specifically engineered to satisfy the requirements for both spatial and temporal transfer functions of the ideal differentiator. The time‐space performance of the device is numerically examined from the output field profile of the classical Gaussian beam or pulse. A wavelength‐scale high resolution for edge detection is attained using the integrated differentiator. This work may pave a potential way to establish ultracompact, high‐bandwidth, and real‐time optical multiple functional computation systems.
The
lithium–sulfur (Li–S) battery is considered as
a promising battery chemistry for next-generation energy storage on
the merits of low cost and high energy density. However, the sluggish
redox kinetics and shuttling effect of lithium polysulfides (LiPSs),
especially at high sulfur loading, result in low sulfur utilization,
low Coulombic efficiency, and short cycle life. Herein, an entangled
N-doped carbon nanotube array with encapsulated Co nanoparticles has
been constructed and used as an efficient host for sulfur cathode
featuring both physical and chemical trapping ability for soluble
LiPSs. Besides, the encapsulated Co nanoparticles combined with N
species can accelerate polysulfides redox, which has been proved by
electrochemical analysis, in situ spectroscopy, and theoretical calculations.
The effective confinement and fast conversion of polysulfides ensure
the Li–S battery with a high capacity of 1045 mAh g–1 at 1 C rate and 77.89% capacity retention even after 1000 cycles,
and these advantages can even be extended to sulfur loading as high
as 15 mg cm–2. More significantly, a pouch cell
assembled with the composite sulfur cathode can deliver a stable cycling
for more than 150 cycles, further demonstrating the great potential
of Li–S batteries for practical applications.
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