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We report a new resin formaldehyde (RF-COOH) microspheres hard templates based method to synthesize NiCo 2 O 4 hollow microspheres with thin/thick single/double/triple-shell. Single-shell NiCo 2 O 4 hollow microspheres are obtained with deionized water as solvent. Furthermore, ethylene glycol can decrease the aquo groups (H 2 O) number within the coordination sphere of Ni 2+ /Co 2+ , which leads to a decrease of hydrated metal ions size and more penetrated metal ions into RF microspheres that is essential to the formation of more shells. Thus, double and triple-shell NiCo 2 O 4 hollow microspheres are harvested when ethylene glycol is solvent and the heating ramp rate are 2 and 5 °C/min, respectively. Larger heating ramp rate (2–5 °C/min) increases the temperature gradient of the infused RF microspheres, which favors the separation between adjacent NiCo 2 O 4 layers and RF cores, and thus resulting in the formation of more shells. What’s more, shells become thick and more compact when the precursor concentration is increased from 0.05 to 0.1 M due to more infused Ni 2+ /Co 2+ . The electrochemical performance for supercapacitors of NiCo 2 O 4 hollow microspheres with thin multi-shells is superior to those with thick single-shell. The better performances are attributed to multi-shells with more electroactive sites and hollow structures as “ion-buffering reservoir”, while thin shell is beneficial to the diffusion of electrolyte/ions. [ABSTRACT FROM AUTHOR]

Noble metal nanocrystals (Au, Pt or AuPt) with controlled compositions and nanostructures were embedded into hollow silica submicrospheres with highly ordered radial mesopores through a one-step sol–gel process. 2,4-Dihydroxybenzoic acid–formaldehyde (RF-COOH) resin submicrospheres were utilized simultaneously as a hard template to create hollow interiors inside the silica submicrospheres and as carriers to transport pregrown metal nanocrystals, including Au nanoparticle (NP), Pt NP, and AuPt nanoalloy, into the submicrospheres. Calcination removes the resin submicrospheres and causes metal nanocrystals embedded into the RF-COOH submicrospheres break into multiple smaller nanoparticles (2–6 nm) that are randomly dispersed in the hollow space of SiO 2 submicrospheres M@SiO 2 (M = Au, Pt or AuPt). The AuPt@SiO 2 submicrospheres showed good catalytic performance for epoxidation of styrene with the conversion and selectivity of 74% and 85%, respectively. The approach reported in this study could potentially be used to simplify the fabrication process of noble metal nanoalloys, which usually entails multiple steps and a previously synthesized hard metal template, and thus guide the design and creation of high-performance catalysts. [ABSTRACT FROM AUTHOR]

Magnetic C–C@Fe3O4 hollow microspheres were prepared by using aerosol-based Fe3O4@C-SiO2 core–shell particles as templates. The magnetic double-shelled microspheres efficiently worked as carriers to load Pt nanoparticles, thus making the catalyst recyclable and reusable. [ABSTRACT FROM AUTHOR]

A novel strategy is proposed by constructing TFSI - ion-sieve interlayer to guide Li-ion selective transport and solid SEI growth. The uniform MgF 2 seeds on the fiber surface reacts rapidly with Li + in electrolyte to form Mg and LiF dual functional sites for the first charging process. Benefiting from the high affinity of LiF, the TFSI - ions is enriched near the anode forming an ion-sieve interlayer, which acts as a protective umbrella and guides priority penetration of Li + due to the coordination reaction with Li + and thus homogenize the Li + flux. While the Mg sites induce Li nucleation with its strong lithiophilicity and facilitate uniform Li plating on fiber surface. Furthermore, as raw material of LiF, the TFSI - enrichment on anode surface is contribute to increasing LiF content in SEI, achieving the stability enhancement and densification of SEI. Of greater importance, the excess Li + can spread to the adjacent Mg sites for nucleation by means of ultralow Li + migration barrier on LiF and Mg. The combination of the ion-sieve homogenization of Li + flux in electrolyte and the uniformity of Li + transport in LiF/Mg solid medium achieves the purpose of uniform Li metal plating/stripping., (© 2024 Wiley‐VCH GmbH.)

The long-term stability of Li-S batteries is significantly compromised by the shuttle effect and insulating nature of active substance S, constraining their commercialization. Developing efficient catalysts to mitigate the shuttle effect of lithium polysulfides (LiPSs) is still a challenge. Herein, we designed and synthesized a rose-like cobalt-nickel bimetallic oxide catalyst NiCo 2 O 4 -O V enriched with oxygen vacancies (O V ) and verified the controllable synthesis of different contents of O V . Introducing the O V proved to be an efficient approach for controlling the electronic structure of the electrocatalyst and managing the absorption/desorption processes on the reactant surface, thereby addressing the challenges posed by the LiPS shuttle effect and sluggish transformation kinetics in Li-S batteries. In addition, we investigated the effect of O V in NiCo 2 O 4 on the adsorption capacity of LiPSs using adsorption experiments and density functional theory (DFT) simulations. With the increase in the level of O V , the binding energy between the two is enhanced, and the adsorption effect is more obvious. NiCo 2 O 4 -O V contributes to the decomposition of Li 2 S and diffusion of Li + in Li-S batteries, which promotes the kinetic process of the batteries.