Silica can be converted to silicon by magnesium reduction. Here, this classical reaction is renovated for more efficient preparation of silicon nanoparticles (nano-Si). By reducing the particle size of the starting materials, the reaction can be completed within 10 min by mechanical milling at ambient temperature. The obtained nano-Si with high surface reactivity are directly reacted with 1-pentanol to form an alkoxyl-functionalized hydrophobic colloid, which significantly simplifies the separation process and minimizes the loss of small Si particles. Nano-Si in 5 g scale can be obtained in one single batch with laboratory scale setups with very high yield of 89%. Utilizing the excellent dispersion in ethanol of the alkoxyl-functionalized nano-Si, surface carbon coating can be readily achieved by using ethanol soluble oligomeric phenolic resin as the precursor. The nano-Si after carbon coating exhibit excellent lithium storage performance comparable to the state of the art Si-based anode materials, featured for the high reversible capacity of 1756 mAh·g after 500 cycles at a current density of 2.1 A·g. The preparation approach will effectively promote the development of nano-Si-based anode materials for lithium-ion batteries.
A bimetallic Ni–Mo nanocomposite as a highly efficient HER catalyst with critical synergetic effect can be obtained from a molybdate incorporated Ni-MOF.
Nickel
nitride (Ni3N) is a superior hydrogen evolution reaction
(HER) catalyst where the nitrogen source is usually ammonia and the
reaction temperature is high during the synthesis process. Herein,
we employed an innovative method to obtain three-dimensional porous
nickel nitride nanosheets on Ni foam (Ni3N/NF) by transforming
Ni(OH)2 nanosheets in N2–H2 glow discharge plasma. The obtained Ni3N/NF displays
a high HER activity with a small overpotential of 44 mV and a low
Tafel slope of 46 mV dec–1, which is competitive
to a Pt/C catalyst. Both the test data and simulation results prove
that active ions and radicals in plasma play essential roles in achieving
the facile nitridation, as well as building a nanostructured morphology
over the Ni3N/NF surface. The unique synthesis method opens
new avenues for metal nitrides of HER catalysts and beyond.
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