Electrocatalytic urea synthesis is a promising alternative
to the
energy-intensive conventional industrial process. However, it lacks
highly active and selective catalyst systems. Herein, we report a
Cu/ZnO stacked tandem gas-diffusion electrode (GDE) for selective
urea synthesis from electrocatalytic CO2 and nitrate reduction
reactions. The ZnO catalyst layer (CL) segment at the inlet provides
a high CO concentration to the downstream Cu CL segment, promoting
the conversion of NO3
– to *NH2. The CO-mediated NH2 formation accelerates the C–N
coupling rate for urea synthesis. As a result, the stacked GDE with
an optimal ZnO/Cu CL area ratio achieves a high Faradaic efficiency
of 37.4% and a high yield of 3.2 μmol h–1 cm–2 for urea at −0.3 V vs RHE under ambient conditions.
This work expands the application of tandem electrodes and realizes
the cascade C–N coupling reaction.
Optimizing the architecture and tailoring the phase composition are useful approaches to increasing electrochemical capacitor energy storage performance. In this work, a novel three-dimensional (3D) hybrid nickel cobalt sulfide wrapped in ultrathin carbon layer (nickel cobalt sulfides@C) was rationally designed and constructed with varied hollow and porous dendritic superstructures. The morphology evolution process has been demonstrated in detail by adjusting the Co/ Ni ratio and reaction duration. Different phases of nickel cobalt sulfides@C can be tailored after sulfuration, enabling the systematic exploration of the energy storage performance with synergistic engineering of architecture and composition. Benefiting from the 3D dendritic superstructures with porous/hollow nature, tunable chemical composition, abundant phase boundaries, enhanced specific surface area, and highly conductive carbon layer matrix, (Ni,Co) 9 S 8 /NiS/Ni 3 S 2 @C yields an outstanding specific capacity of 856.6 C g −1 at the current density of 1 A g −1 . Furthermore, the assembled asymmetric supercapacitor device presents higher energy density of 70.6 Wh kg −1 and power density of 8873.5 W kg −1 with excellent cycling stability. This synthetic strategy highlights the crucial role of synergistic engineering of architecture and chemical composition in practical energy storage, and the as-designed functional materials will be a competitive and promising candidate for robust electrochemical capacitor energy storage and other applications.
Electrodes with hierarchical nanoarchitectures could promote electrochemical properties due to large exposed active sites and quick charge transfer. Herein, the in situ grown hierarchical NiO nanosheet@nanowire films are reported by...
Dual-band electrochromic (EC) films selectively modulating visible (VIS) and near-infrared (NIR) light promise an attractive option for efficiently utilizing solar energy. Anatase titanium dioxide (TiO 2 ) promises dual-band EC capability; however, it suffers from the difficulty in circumventing the obstacle in the NIR region and sluggish reaction kinetics as well as poor cycling stability. In this work, 2D (Nb, F) co-doped TiO 2 nanosheets (NSs) arrays are reported as an effective singlecomponent dual-band EC material. The co-doping can induce an oriented growth of freestanding ultrathin NSs with exposed (001) facets which promote the EC reaction kinetics. The high aspect ratio and orientation of the nanosheets favor the localized surface plasmon resonance (LSPR) effect triggered by electrochemical bias voltages, thus achieving independent modulation of the NIR transmittance. Three application scenarios of the NSs can be presented based on selective, efficient, and high optical modulation in the NIR and VIS regions (79.5% at 700 nm and 78.4% at 1300 nm, respectively), unprecedented fast bleaching/coloring times (3.0/8.4 s), and a long cycle life (500 cycles). Moreover, the films exhibit multi-color EC and energy storage materials. This work may provide an insight into the single-component dual-band EC mechanism of 2D TiO 2 nanostructures and present promising potential for energy saving and smart display applications.
The capacity of Li 4 Ti 5 O 12 (LTO) at high rates is limited due to the polarization caused by its modest Li-ion (Li + ) diffusion coefficient and low electrical conductivity. Coating with ionic conductors is an available method to ameliorate charge transport. Li 1+x Al x Ti 2−x (PO 4 ) 3 ion conductors with thermal, chemical, and electrochemical stabilities have been proven to be modification materials for electrodes. Herein, the Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 (LATP) precursor dispersion with optimized preparation is applied to the surface modification of LTO by a dynamic mix-drying method. A proper amount of LATP ultrafine particle coating could develop the ion transport rate in the electrode and restrain side reactions. The 2 wt % LATP−LTO anode exhibits an optimized capacity of 168.2 mA h g −1 at 0.1 A g −1 and retains 96.7% of its capacity after 5000 cycles at 5.0 A g −1 , while the P-LTO anode retains 86.3% of the capacity. Improved Li + transport and interface stability in the electrodes lead to the boosted rate and cycling stability. The LATP-modified LTO composites provide a possibility for the further application of related materials in the energy storage field.
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