Correction to Highly Efficient Retention of Polysulfides in "Sea-Urchin"-Like Carbon Nanotube/Nanopolyhedra Superstructures as Cathode Material for Ultralong-Life Lithium-Sulfur Batteries

Synergistic Effect between Monodisperse Fe3O4 Nanoparticles and Nitrogen-Doped Carbon Nanosheets to Promote Polysulfide Conversion in Lithium-Sulfur Batteries

Effective fabrication of electrocatalysts active in anchoring and converting lithium polysulfides is critical for the manufacturing of high-performance lithium-sulfur batteries (LSBs). In this study, original Fe₃O₄ nanospheres with diameters close to 12 nm were finely dispersed over a porous nitrogen-doped carbon matrix by the freeze-drying method to produce a three-dimensional composite material (nano-Fe₃O₄/PNC) suitable for application as a sulfur host in LSBs. Nano-Fe₃O₄/PNC loaded with sulfur (S@nano-Fe₃O₄/PNC) was used as a cathode in a Li-S cell, whose initial discharge specific capacity reached 1256 mA h g^-1 at a 0.1 C rate. After 100 charge-discharge cycles at a 0.2 C rate, the reversible capacity of S@nano-Fe₃O₄/PNC remained at 745 mA h g^-1, demonstrating a capacity retention rate of 70%. Importantly, a high Coulombic efficiency of more than 99% was achieved, indicating effective inhibition of the polysulfides' "shuttle effect" by nano-Fe₃O₄/PNC. The use of electrolytes containing lithium nitrate further reduces the "shuttle effect" of polysulfides. This study demonstrates the synergistic effect between metal oxide nanoparticles and N-doped carbon, which plays an important role in promoting the adsorption and conversion of polysulfides in LSBs.

Morphological and Electronic Dual Regulation of Cobalt-Nickel Bimetal Phosphide Heterostructures Inducing High Water-Splitting Performance

Electrocatalytic water splitting (EWS) is a key technology for generating clean and sustainable hydrogen, which can store abundant energy but is impeded by the insufficient efficiency of the anode and cathode catalyst. Designing and constructing non-noble metal composite bifunctional electrocatalysts for promoting both the cathodic hydrogen evolution (HER) and anodic oxygen evolution reactions (OER) is clearly of great importance for EWS. Thus, the chemical composition and morphology of cobalt-nickel bimetal phosphide (Ni, Co)₂P nanoparticles (NPs) encapsulated in nitrogen-doped carbon nanotube hollow microspheres (NCNHMs) can regulate the redox-active sites and enhance the electron transfer, resulting in superior splitting efficiency. Contributing to the synergistic effects between highly active Co-Ni bimetal phosphide NPs and NCNHMs, the obtained Co-Ni bimetal phosphide/NCNHMs display remarkable electrochemical performance for water splitting compared with Ni₂P/NCNHMs. Therefore, the Ni_1.4Co_0.6P/NCNHMs catalysts achieved through a nitriding-phosphidation strategy derived from a hollow Ni_1.4-Co_0.6-based metal organic framework (MOF) exhibit superior HER catalytic activity (87.9 mV at 10 mA cm^-2 tested in 0.5 M H₂SO₄ and 64.4 mV at 10 mA cm^-2 tested in 1 M KOH) and OER catalytic activity (320.0 mV at 10 mA cm^-2 tested in 1 M KOH). The Ni_1.4Co_0.6P/NCNHMs deliver excellent water-splitting catalytic activity (1.55 V at 10 mA cm^-2 tested in 1 M KOH), which is competitive with that of current non-noble metal electrocatalysts. Density functional theory (DFT) simulations and related experimental results suggest that the electron transfer from Co doping and coating with NCNHMs improves the electronic states, which would enhance the binding strength with H-bonds and then promote the electrocatalytic activity.