NiO/Fe 3 O 4 /rGO composite materials were successfully obtained via a solvothermal route and characterized by charge/discharge test, TEM, XRD, SEM, EIS, HRTEM, XPS, CV, etc. The results showed that the Fe 3 O 4 nanospheres have an average size around 150 nm, NiO is relatively larger (about 300 nm) and agglomerated by rod-shaped particles. The nanospheres of Fe 3 O 4 and rod-shaped NiO particles were distributed on the surface of reduced grapheme oxide. The BET specific surface and BJH desorption average pore diameter of NiO/Fe 3 O 4 /rGO are 497.26 m 2 g −1 and 1.23 nm, respectively, so it improves the contact area between electrode materials and electrolyte, make ion diffusion path shorter and facilitates ion insertion/desertion. Discharge capacity was 841 mAh g −1 at the first cycle and maintain 647 mAh g −1 after 200 cycles at the current density of 500 mA g −1 , and even at the current density of 1000 mA g −1 , the discharge capacity can keep 582 mAh g −1 after 200 cycles with a well Coulombic efficiency and retention. And electrochemical impedance of NiO/Fe 3 O 4 and NiO/Fe 3 O 4 /rGO is 110 Ω and 75 Ω, respectively, indicating that the material has a good ionic conductivity.
Naeem Akram,Wenlan Ma,Shehla Riaz,Jia Guo,Ali Ahmad,Jide Wang
In this study, Ni-Fe-based Prussian Blue Analogues (Ni-Fe PBA) served as precursors, giving rise to a NiO/Fe 3 O 4 -based bimetallic catalyst that underwent comprehensive examination for both chemocatalytic water oxidation and photocatalytic degradation of organic dyes. The morphologies and chemical compositions of the precursor and resultant bimetallic catalysts were thoroughly characterized using XRD, SEM, XPS, mapping, and FTIR techniques. The results indicated that the catalytically active center is the NiO/Fe 3 O 4 -based bimetallic nanocomposite. The in-situ-synthesized bimetallic catalyst demonstrated remarkable catalytic oxidation activity when evaluated with Sodium Persulfate (PS) as an oxidant. Oxygen evolution results revealed an impressive catalytic water oxidation activity, with an O 2 production rate of approximately 1594.3 µmol·g −1 ·h −1 . Moreover, the NiO/Fe 3 O 4 catalyst was utilized as a heterogeneous photocatalyst to activate photosensitizer (PS) for the two azo dye’s deterioration caused by the exposure to visible light. Both organic dyes were photocatalytically degraded with great efficiency when Fe 3 O 4 and NiO were combined because they increased the catalyst’s capacity to absorb light. Electron Spin Resonance (ESR) and radical trapping studies revealed that sulfate (SO4· - ) and hydroxyl (OH·) radicals played pivotal roles. The degradation mechanism and pathway for Rhodamine B (RhB) were also elucidated. The exceptional recyclability and stability of the NiO/Fe 3 O 4 catalyst make it particularly promising for potential applications in water treatment, addressing challenges related to energy sustainability and environmental toxicity.
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