【公開日：2025.06.10】【最終更新日：2025.05.26】
課題データ / Project Data
課題番号 / Project Issue Number
24NU0223
利用課題名 / Title
Green synthesized CoFe2O4/rGO nanocomposites as magnetically separable and reusable photocatalysts for organic toxic dye degradation
利用した実施機関 / Support Institute
名古屋大学 / Nagoya Univ.
機関外・機関内の利用 / External or Internal Use
外部利用/External Use
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）次世代ナノスケールマテリアル/Next-generation nanoscale materials（副 / Sub）マテリアルの高度循環のための技術/Advanced materials recycling technologies
キーワード / Keywords
Green synthesis, Photocatalysis, CoFe2O4/rGO, Nanocomposite,磁気特性/ Magnetic properties measurement,磁気特性測定システム/ Magnetic property measurement system,資源代替技術/ Resource alternative technology,ナノカーボン/ Nano carbon,X線回折/ X-ray diffraction,ナノ粒子/ Nanoparticles,電子顕微鏡/ Electronic microscope,ナノシート/ Nanosheet
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
Suharyadi Edi
所属名 / Affiliation
Gadjah Mada University Department of Physics
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
Dr. Takeshi Kato,Dr. Daiki Oshima
利用形態 / Support Type
（主 / Main）共同研究/Joint Research（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
NU-002：X線粉末回折装置
NU-103：高分解能透過電子顕微鏡システム
NU-259：磁気特性評価システム群
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
The development of an efficient and environmentally friendly method for the separation of photocatalytic nanoparticles from degraded solutions is crucial to facilitate their repeated use. The development of magnetic-based nanocomposites with high catalytic performance and facile separation is an effective strategy for wastewater treatment. Here, we present the photocatalytic degradation of magnetically separable green synthesized cobalt ferrite/reduced graphene oxide (CoFe2O4/rGO) under ultra-violet irradiation. The CoFe2O4 nanoparticles were synthesized via a green approach using Moringa oleifera leaf extract as a reducing and capping agent, while rGO was prepared by reducing GO with Amaranthus viridis leaf extract. The crystallite size decreased with increasing rGO concentration. The morphological images illustrate that the particles were nearly spherical in shape and attached to the rGO sheet. Analysis of the magnetic properties revealed that the nanocomposite exhibited ferromagnetic behavior. The CoFe2O4/rGO 5:5 nanocomposite exhibited optimal efficiency in rhodamine B photodegradation, reaching a degradation rate of 78.6 % within 120 mins, with 20 min intervals. The magnetic separability of the nanocomposites permitted recycling for up to three consecutive cycles. In light of these findings, the CoFe2O4/rGO nanocomposite demonstrates considerable promise as a standalone photocatalyst for the remediation of organic contaminants in the environment.
実験 / Experimental
The synthesis of CoFe2O4 nanoparticles was carried out by a simple co-precipitation method, according to the following steps. CoCl2.6H2O (1 g) and FeCl3.6H2O (1.7 g) were dissolved separately in 15 mL distilled water and stirred for 3 min. The two solutions were then mixed and stirred for 5 min. The M. oleifera solution was then added dropwise with continuous stirring for 30 min to form solution X. Meanwhile, 1.5 M NaOH solution was prepared by dispersing it into 25 mL of distilled water and stirring for 15 min at 60 °C. Next, solution X was slowly added to the NaOH solution at 80 °C with stirring for 60 min. After cooling to room temperature, a brownish-black solution was precipitated and washed several times with distilled water. An external magnet was used to separate the nanoparticles from the solution effectively. The washed precipitate was dried for 7 h at 80 °C. Next, the dried precipitate was crushed and subjected to calcination for 5.5 hours at 600 °C in a furnace, resulting in green synthesized CoFe2O4 nanoparticles in the form of a black powder. rGO (0.6 g) was mixed with 195 mL of distilled water and 5 mL of A. viridis solution and sonicated for 60 mins. Afterwards, 1 mL of hydrazine was added to the solution to reduce the GO sheets to rGO sheets and then stirred at a temperature of 70 °C for 60 mins. The rGO solution was then centrifuged and the precipitate dried at 100 °C for 4 h. CoFe2O4 (0.5 g) was dissolved in ethanol (10 mL) via sonication for 30 mins. Subsequently, 0.1 g was added to the solution, which was then stirred for 1 h at room temperature. The mixture was then precipitated and the precipitate separated using an external magnet and washed several times with distilled water. Finally, the precipitate was dried at 100 °C for 2 h to obtain a green synthesized CoFe2O4/rGO powder. The phase and crystal structures of all the samples were studied by X-ray diffraction (XRD, Rigaku Smartlab) analysis using Cu-Kα radiation (λ = 1.5406 Å). The morphology and particle size were analyzed by transmission electron microscopy (TEM, JEM-2100F). Fourier transform infrared (FTIR, Shimadzu IR Prestige-21) was performed in the range of 400 to 4000 cm-1 to identify functional groups. UV-visible spectroscopy (Shimadzu UV-1900 spectrophotometer) was used to determine the sample optical properties. Magnetic properties were assessed using a vibrating sample magnetometer (VSM, TM-VSM271483-HGC).
結果と考察 / Results and Discussion
TEM was used to investigate the morphology and size of the nanoparticles. TEM image shows the rGO in the form of a sheet-like structure exhibiting a tangled network. This observation corroborates the formation of the rGO layer through reduction of the layered GO structure. Concurrently, the folded and curved transparent planes in the image indicates a two-dimensional single-layer structure. In the micrograph of the CoFe2O4/rGO nanocomposite, well-resolved lattice fringes with an interplanar distance of 0.25 nm—corresponding to the (311) planes of CoFe2O4—are observed [21,50,51]. This finding was corroborated by the XRD analysis. The rGO sheets effectively reduced the nanoparticle agglomeration, which was also supported by the TEM images of the composites. The XRD patterns of CoFe2O4 and the CoFe2O4/rGO nanocomposites shows that the distinct peaks were observed at 2θ = 30.2, 35.6, 43.2, 53.6, 57.1, 62.7, and 74.2°, corresponding to the (220), (311), (422), (511), (440), (620), and (533) crystal planes, respectively. These peaks match the crystallography open database No. 5910063, confirming the presence of CoFe2O4 in the cubic spinel structure. The results display peaks corresponding to both rGO and CoFe2O4, further verifying the presence of rGO and cubic spinel CoFe2O4 phases in the CoFe2O4/rGO nanocomposites. The magnetic properties of the samples were investigated using VSM measurements at room temperature measured over a magnetic field range of -15 to 15 kOe. The results depicts the hysteresis curves of CoFe2O4 and CoFe2O4/rGO nanocomposites at varying concentrations. The CoFe2O4 nanoparticles exhibit a saturation magnetization (Ms) value of 49.9 emu/g. Surface modification of the CoFe2O4 nanoparticles resulted in a lower Ms than that of pure CoFe2O4 nanoparticles. The Ms value decreased with increasing rGO concentration, reaching 27 emu/g for the 5:5 CoFe2O4/rGO nanocomposite. Furthermore, with the addition of rGO, the coercivity decreased from 600 Oe for the CoFe2O4 nanoparticles to 400 Oe for the CoFe2O4/rGO 5:5 nanocomposites.
図・表・数式 / Figures, Tables and Equations
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
Acknowledgments: The authors thank Prof. S. Arai, Ms. M. Nakano, and Ms. K. Yoda of Nagoya University for their assistance with the TEM observations.Fundings: This research was funded by the grant of PMDSU 2022-2024, the Ministry of Education, Culture, Research & Technology, Republic of Indonesia; the grant of International Joint Research Academy (IJRA) UGM 2024, the Ministry of Education, Culture, Research & Technology, Republic of Indonesia; and the Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM), the Ministry of Education, Culture, Sports, Science and Technology (MEXT) (Proposal Numbers: JPMXP1223NU0271 and JPMXP1224NU0223), Japan.
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
-
Dyah Ayu Larasati, Green synthesized CoFe2O4/rGO nanocomposites utilizing plant leaf extracts as magnetically separable and reusable photocatalysts for organic toxic dye degradation, Journal of Water Process Engineering, 69, 106708(2025).
DOI: https://doi.org/10.1016/j.jwpe.2024.106708
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件