Abstract Among the exfoliation processes applied on layered materials, it is the first time to explore the ultrasonic exfoliation in water for improving the catalytic properties of NiFe2O4/CB (CB = carbon black) nanospheres towards the electrocatalytic hydrogen evolution reaction (HER) in acidic media. It is found that after exfoliation, the overpotential of HER on NiFe2O4/CB nanospheres is improved by about 90 mV at a current density of 10 mA cm−2. Moreover, the exfoliated NiFe2O4/CB nanospheres are not only more stable than the commercial Pt/C catalyst, but also they exhibit an overpotential improvement of about 100 mV at 50 mA cm−2, after 6000 CV cycles. It is also found that the ultrasonic process causes uniformed NiFe2O4/CB particles, an increase of the electrochemical active sites, enriched Fe2+ ion and Fe3+ occupied on tetrahedral sites on the surface layer of the NiFe2O4/CB nanospheres, as resulted from the analysis with XPS, FTIR etc., leading to a higher activity and excellent durability. Furthermore, the approach also provides new insights on processing of materials in a green route.

中文翻译：

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一种提高 NiFe2O4/CB 纳米球产氢电催化活性和稳定性的绿色方法

摘要 在应用于层状材料的剥离工艺中，首次探索在水中超声剥离以提高 NiFe2O4/CB（CB = 炭黑）纳米球在酸性介质中对电催化析氢反应（HER）的催化性能。 . 发现剥离后，在 10 mA cm-2 的电流密度下，NiFe2O4/CB 纳米球上的 HER 过电位提高了约 90 mV。此外，剥离的 NiFe2O4/CB 纳米球不仅比商业 Pt/C 催化剂更稳定，而且在 6000 次 CV 循环后，它们在 50 mA cm-2 下表现出约 100 mV 的过电位改善。还发现超声处理使 NiFe2O4/CB 颗粒均匀，电化学活性位点增加，XPS、FTIR等分析结果表明，NiFe2O4/CB纳米球表面层的四面体位点富集Fe2+离子和Fe3+，具有更高的活性和优异的耐久性。此外，该方法还为以绿色路线加工材料提供了新的见解。