Reduced graphene oxide (rGO) encapsulated sulfur spheres for the Li-S batteries were prepared via the redox reaction between sodium polysulfide. XRD spectra showed that the diffraction peak of graphite oxide (GO) at 10° disappeared, while the relatively weak diffraction peak at 27° belongs to graphene emerged. FT-IR spectra showed that the vibrations of the functional groups of GO, such as 3603 cm −1 , 1723 cm −1 and 1619 cm −1 which contributed from OH, C O C and C O respectively, disappeared when compared to the spectra of GSC. SEM observations indicated that the optimum experimental condition followed as: mass ratio of GO and S was 1:1, 10% NaOH was used to adjust the pH. EDX analysis showed that the sulfur content reached at 68.8% of the composite material. The resultant electric resistance was nearly less than GO’s resistance in three orders of magnitude under same condition. Further electrochemical performance tests showed a coulombic efficiency was 96% from the first cycle capacity was 827 mAh g −1 , to 388 mAh g −1 in the 100 cycles. This study carries substantial significance to the development of Li-S battery cathode materials.
Yuanxin Zeng,Wenyi Dong,Hongjie Wang,Xiao Huang,Ji Li
To obtain high-quality VFAs production from primary sludge , a novel strategy that combined peroxymonosulfate (PMS) pretreatment and alkaline fermentation (i.e., PMS & pH9) was proposed in the study. The results showed that PMS & pH9 was efficient in sludge solubilization and hydrolysis, resulting in a maximal VFAs yield of 401.2 mg COD/g VSS, which was 7.3-, 2.1-, and 8.8-fold higher than the sole PMS, sole pH9, and control, respectively. Acetate comprised 87.6% of VFAs in this integration system. Mechanism investigations revealed that sulfate and free radicals produced by PMS play roles in improving VFAs yield under alkaline conditions. Besides, sulfate also aided in C3∼C5 VFAs converting to acetate under alkaline conditions depending on the increase of incomplete-oxidative sulfate-reducing bacteria (iso-SRB) (i.e., Desulfobulbus and Desulfobotulus ). Moreover, the relative abundances of acid-forming characteristic genera (i.e., Proteiniborus , Proteinilcasticum , and Acetoanaerobium ) were higher in PMS & pH9.
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