Building a rational nanoarchitecture of TiO2 nanowires/RGO composite is a promising method to satisfy the demands of excellent Li+/Na+ storage performance.
Silicon oxycarbides (SiOC) are regarded as potential anode materials for lithium-ion batteries, although inferior cycling stability and rate performance greatlyl imit their practical applications. Herein, amorphous SiOC is synthesized from Chlorella by means of ab iotemplate methodb ased on supercritical fluid technology.O nt his basis, tin particles with sizes of several nanometersa re introduced into the SiOC matrix through the biosorptionf eature of Chlorella. As lithi-um-ionb attery anodes,S iOC and Sn@SiOC can deliver reversible capacities of 440 and 502 mAh g À1 after 300 cycles at 100 mA g À1 with great cyclings tability. Furthermore, as-synthesized Sn@SiOC presents an excellent high-rate cycling capability, which exhibits ar eversible capacity of 209 mAh g À1 after 800 cycles at 5000 mA g À1 ;t his is 1.6 times higher than that of SiOC. Such an ovel approach has significancef or the preparation of high-performance SiOC-based anodes.
Building a rational nanoarchitecture of a quantum dots (QDs)/graphene composite is a promising method to satisfy the demands of high sodium-ion storage capacity, good rate capability, and superb cycling stability. Here, a powerful supercritical CO 2 -fluid strategy is provided to fabricate a TiO 2 QDs/reduced graphene oxide (RGO) composite. The prepared nanocomposite shows a porous and stable structure with a tight union of TiO 2 QDs (∼3.7 nm) and RGO supports, which offers numerous fast electron and ion transmission routes and high mechanical stability. When it cycles at 0.05 A g −1 as the anodic material for Na-ion batteries (SIBs), the TiO 2 QDs/RGO electrode shows a reversible capacity of 241 mA h g −1 with a low capacity loss of 18.5% after 300 cycles. Even increasing the current density up to 5 A g −1 , an excellent capacity as high as 108 mA h g −1 still can be achieved with a low capacity loss of 11.5% over 5000 cycles. This work demonstrates a new supercritical CO 2 -fluid-assisted strategy for future development of brilliant QDs/RGO composite materials for high-performance SIBs.
The electrocatalytic hydrogen evolution reaction (HER)
by nonprecious
metal-based cathodes provides a cost-effective way to store renewable
energy as hydrogen fuel. However, pH variation on the cathode surface
during electrolysis may lead to performance deterioration. Herein,
the heterostructure electrode composed of nitrogen-doped ditungsten
carbide/monolithic tungsten interface (N–W2C/W)
is developed. The as-obtained electrode showed superior HER performance
in pH-universal conditions, achieving −10 mA cm–2 with small overpotentials of 90, 90, and 82 mV in acidic, neutral,
and alkaline electrolytes, respectively. Moreover, the electrocatalyst
shows negligible performance decay after 24 h at the current densities
of even −500 mA cm–2. Theoretical studies
reveal that the interface W site exhibits suitable Gibbs free energy
of hydrogen adsorption. Moreover, the unique interfacial structure
provides synergistic active sites for water dissociation. This work
provides an approach to design an interfacial structure based on nonprecious
metals for highly efficient HER electrocatalysis.
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