In this work, nickel ferrite nanoparticles (NiFeO NPs) was prepared to improve hydrogen (H) production by dark fermentation. Moderate amounts (50-200 mg/L) promoted H generation, while excess NiFeO NPs (over 400 mg/L) lowered H productivity. The highest H yields of 222 and 130 mL/g glucose were obtained in the 100 mg/L (37 °C) and 200 mg/L NiFeO NPs (55 °C) groups, respectively, and the values were 38.6% and 28.3% higher than those in the control groups (37 °C and 55 °C). Soluble metabolites showed that NiFeO NPs enhanced the butyrate pathway, corresponding to the increased abundance of Clostridium butyricum in mesophilic fermentation. The endocytosis of NiFeO NPs indicated that the released iron and nickel favored ferredoxin and hydrogenase synthesis and activity and that NiFeO NPs could act as carriers in intracellular electron transfer. The NPs also optimized microbial community structure and increased the levels of extracellular polymeric substances, leading to increased H production.
Key Laboratory of Functional Inorganic Material Chemistry, (Ministry of Education of China), School of Chemistry and Materials Science, Heilongjiang University, Harbin, 150080, P. R. China.
Although the activity of electrocatalysts towards oxygen evolution reaction (OER) has achieved considerable improvement by modulating the intrinsic electron structure, the role of supports to OER performance, often being reduced to enhancing the conductivity, is not fully explored. In this paper, a proof-of-concept study based on a series of hybrids of nickel iron (hydr)oxide nanoparticles (NiFeO NPs) and carbon supports with different oxidation level compared the motivation of supports for OER activity. The key to implementation lay in anchoring and growing of NiFeO NPs on the various carbon supports by electrostatic assembly and subsequent in-situ reduction.
Rechargeable Zn-air battery is limited by the sluggish kinetics and poor durability of the oxygen catalysts. In this Research Article, a new bifunctional oxygen catalyst has been developed through embedding the ultrafine NiFeO nanoparticles (NPs) in a porous amorphous MnO layer, in which the NiFeO-core contributes to the high activity for the oxygen evolution reaction (OER) and the amorphous MnO-shell functions as active phase for the oxygen reduction reaction (ORR), promoted by the synergistic effect between the NiFeO core and MnO shell. The synergistic effect is related to the electron drawing of NiFeO core from MnO shell, which decreases the affinity and adsorption energy of oxygen on MnO shell and significantly increases the kinetics of ORR.
