A Deep Reduction and Partial Oxidation Strategy for Fabrication of Mesoporous Si Anode for Lithium Ion Batteries

A deep reduction and partial oxidation strategy to convert low-cost SiO₂ into mesoporous Si anode with the yield higher than 90% is provided. This strategy has advantage in efficient mesoporous silicon production and <i>in situ</i> formation of several nanometers SiO₂ layer on the surface of silicon particles. Thus, the resulted silicon anode provides extremely high reversible capacity of 1772 mAh g^–1, superior cycling stability with more than 873 mAh g^–1 at 1.8 A g^–1 after 1400 cycles (corresponding to the capacity decay rate of 0.035% per cycle), and good rate capability (∼710 mAh g^–1 at 18A g^–1). These promising results suggest that such strategy for mesoporous Si anode can be potentially commercialized for high energy Li-ion batteries

SnS₂- Compared to SnO₂‑Stabilized S/C Composites toward High-Performance Lithium Sulfur Batteries

The common sulfur/carbon (S/C) composite cathodes in lithium sulfur batteries suffer gradual capacity fading over long-term cycling incurred by the poor physical confinement of sulfur in a nonpolar carbon host. In this work, these issues are significantly relieved by introducing polar SnO₂ or SnS₂ species into the S/C composite. SnO₂- or SnS₂-stabilized sulfur in porous carbon composites (SnO₂/S/C and SnS₂/S/C) have been obtained through a baked-in-salt or sealed-in-vessel approach at 245 °C, starting from metallic tin (mp 231.89 °C), excess sulfur, and porous carbon. Both of the in situ-formed SnO₂ and SnS₂ in the two composites could ensure chemical interaction with lithium polysulfide (LiPS) intermediates proven by theoretical calculation. Compared to SnO₂/S/C, the SnS₂/S/C sample affords a more appropriate binding effect and shows lower charge transfer resistance, which is important for the efficient redox reaction of the adsorbed LiPS intermediates during cycling. When used as cathodes for Li–S batteries, the SnS₂/S/C composite with sulfur loading of 78 wt % exhibits superior electrochemical performance. It delivers reversible capacities of 780 mAh g^–1 after 300 cycles at 0.5 C. When further coupled with a Ge/C anode, the full cell also shows good cycling stability and efficiency

Phase-Transition-Induced Surface Reconstruction of Rh₁ Site in Intermetallic Alloy for Propane Dehydrogenation

The fine-tuning of the geometric and electronic structures of active sites plays a crucial role in catalysis. However, the intricate entanglement between the two aspects results in a lack of interpretable design for active sites, posing a challenge in developing high-performance catalysts. Here, we find that surface reconstruction induced by phase transition in intermetallic alloys enables synergistic geometric and electronic structure modulation, creating a desired active site microenvironment for propane dehydrogenation. The resulting electron-rich four-coordinate Rh1 site in the RhGe0.5Ga0.5 intermetallic alloy can accelerate the desorption of propylene and suppress the side reaction and thus exhibits a propylene selectivity of ∼98% with a low deactivation constant of 0.002 h–1 under propane dehydrogenation at 550 °C. Furthermore, we design a computational workflow to validate the rationality of the microenvironment modulation induced by the phase transition in an intermetallic alloy

Multigram-Scale Synthesis of High-Pt-Content PtCo Intermetallic Catalysts for Proton Exchange Membrane Fuel Cells

Carbon-supported PtCo intermetallic nanoparticles rank as one of the most efficient cathode catalysts for proton exchange membrane fuel cells (PEMFCs). Nevertheless, developing simple and scalable synthetic approaches for effective size control of this type of catalyst at high Pt contents continues to be a significant challenge. Herein, we introduce a sulfur-containing molecule-assisted ball-milling method, enabling the multigram-scale synthesis of PtCo intermetallic catalysts with a high Pt content of 48 wt %. This method results in a fine dispersion of PtCo intermetallic nanoparticles on carbon black supports with an average particle size of 5.29 nm. The resulting catalyst demonstrates remarkable performance in H2-Air PEMFC tests, exemplified by a power density of 1.16 W/cm2 at 0.7 V and maintaining 65% of its mass activity after an accelerated durability test