【公開日：2024.07.25】【最終更新日：2024.05.15】

課題データ / Project Data

課題番号 / Project Issue Number

23SH0016

利用課題名 / Title

Development of Hybrid Carbon nanomaterials

利用した実施機関 / Support Institute

信州大学 / Shinshu 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）物質・材料合成プロセス/Molecule & Material Synthesis

【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）革新的なエネルギー変換を可能とするマテリアル/Materials enabling innovative energy conversion

キーワード / Keywords

電子顕微鏡/ Electronic microscope,ナノカーボン/ Nano carbon,ナノチューブ/ Nanotube,ナノ多孔体/ Nanoporuous material,ナノシート/ Nanosheet,電極材料/ Electrode material,エネルギー貯蔵/ Energy storage,環境発電/ Energy Harvesting

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)

Winadda Wongwiriyapan

所属名 / Affiliation

College of Materials and Innovation Techenology, King Mongkut's Institute of Technolgy Ladkrabang

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

Assoc.Prof.Kenji Takeuchi,Assoc.Prof.Masatsugu Fujishige

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

SH-004：光電子分光装置
SH-006：飛行時間型二次イオン質量分析装置
SH-001：ダブル球面収差補正付透過型電子顕微鏡

報告書データ / Report

概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)

We combine the activated carbon (AC) and the manganese dioxide (MnO_x) in a hybrid electrode to overcome the low capacitance of activated carbon and MnOx by exploiting the large surface area of AC and the fast reversible redox reaction of MnO_x. Firstly, synthesis of MnO_x was investigated. A MnO_x hybrid structure was successfully synthesized using electrodeposition and successive ionic layer adsorption and reaction (SILAR) techniques which are simple, cost-effective, and low-temperature wet chemical processes. It was found that MnO_xmorphology is different depending on manganese precursors and synthesis techniques. Sea-grape-like and bird nest-like morphologies were obtained via the electrodeposition technique, while flower-like and nanoparticle morphologies were formed via the SILAR technique using manganese acetate and manganese sulfate as precursors, respectively. The hybrid structure of the nanoparticle-decorated bird nest-like heterostructure was prepared using manganese sulfate electrodeposition and subsequent SILAR deposition of manganese acetate. X-ray photoelectron spectroscopy confirmed the Mn3O4 formation. Electrochemical properties of manganese oxide hybrid structure were systematically studied with cyclic voltammetry and galvanostatic charge–discharge, showing the highest areal capacitance of 390 mF/cm² at 0.1 mA/cm² with series and charge transfer resistances down to 4.55 and 4.91 Ω in 1 M sodium sulfate electrolyte. 

実験 / Experimental

(1) MnO_x Deposition Using the Electrodeposition MethodFirstly, 1 cm × 1 cm stainless steel 304 (SS304) was used as a substrate for cathodic electrodeposition using a graphite rod with a diameter of 6 mm as a positive electrode. MnO_x film was deposited on SS304 substrate in galvanostatic mode at a current density of 1 mA/cm² for 10 min, then rinsed with DI water and heated at 80°C overnight. The MnO_x precursors were 0.1 M MnSO₄ and 0.1 M Mn(CH₃COO)₂ (hereinafter referred to as EPD-S and EPD-A, respectively).

(2) MnO_x Deposition Using the Successive Ionic Layer Adsorption and Reaction (SILAR) MethodThe cleaned SS304 substrate was first soaked in manganese precursor for 1 min and immersed in DI water. After that, the SS304 substrate was soaked in 1 M NaOH for 1 min and immersed in DI water. These steps were repeated for 20 cycles. The deposited film was kept at 80°C overnight. The MnO_x precursors were 0.1 M MnSO₄ and 0.1 M Mn(CH₃COO)₂ (hereinafter referred to as SIL-S and SIL-A, respectively).

(3) MnO_x Hybrid Structure Using the Electrodeposition and Successive Ionic Layer Adsorption and Reaction (SILAR) MethodsHybrid structure of MnO_x was done by combining two deposition techniques, electrodeposition and SILAR methods. In the first step, the electrodeposition method was chosen for the deposition of the first layer to ensure a good contact between MnO_x and SS304 substrate. The electrodeposition process was carried out in the same procedure to that of a single-layer deposition, as mentioned earlier. For the second layer, to prevent damaging the electrodeposited structure, the SILAR method was employed. The SILAR deposition processes were identical to the single layer deposition as described above. The resulting hybrid film, known as HYB-A, was created using MnSO₄ precursor for the first layer and Mn(CH₃COO)₂ precursor for the second layer. The hybrid film, however, is referred to as HYB-S when Mn(CH3COO)₂ precursor was employed for the first layer and MnSO₄ precursor for the second layer.

結果と考察 / Results and Discussion

(1)  Morphological Structure of MnOxThe morphological structures of MnOx deposited on SS304 substrates were captured by FE-SEM at various magnifications. The MnOx film electrodeposited by the Mn(CH₃COO)₂ precursor showed the sea-grape-like morphology (Figure 1a). Nanoparticles with a diameter range from 70 to 80 nm attached on a long branch. The MnOx film electrodeposited by MnSO₄ precursor showed the interconnected bird nest-like morphological structure (Figure 1b), which could act as a high surface layer for hybrid film to enhance areal capacitance. For the SILAR deposition technique, the obtained MnO_x films from both precursors (Figure 1c,d). Both films exhibited a structure of uniformly dispersed MnO_x nanoparticles, with sporadically grown spiky flowers observed on the surface of the electrodes. When comparing between two manganese precursors, the flowers from Mn(CH₃COO)₂ were larger in diameter. This was caused by higher deposition rate when the more stable Mn(III) species, compared to MnSO₄, were oxidized to Mn(IV). The hybrid MnO_x films were the combination of two deposition techniques, electrodeposition and SILAR. The initial layer was electrodeposited with one of the manganese precursors, and the second layer was deposited using the SILAR technique and a different precursor. Figure 1e depicts the interconnected bird nest-like structure of the MnO_x film electrodeposited by MnSO₄ precursors, which served as a high surface area substrate for the second layer of MnO_x film deposited with Mn(CH₃COO)₂ precursors employing the SILAR technique (so-called HYB-A). For the HYB-S film, the precursors for electrodeposition and SILAR were changed to Mn(CH₃COO)₂ and MnSO₄ for the first and second layers, respectively. The hybrid MnO_x film structure retained the characteristics of both precursors, resulting in an aggregated nanoparticle structure (Figure 1f). 
(2)  Elemental composition of MnOxThe X-ray photoelectron spectroscopy (XPS) results of the MnO_x films deposited using the electrodeposition and SILAR methods are shown in Figure 2. The oxidation number, determined by the multiplet energy difference, of the films ranged from 2 to 3, indicating that the films were composed of Mn₃O₄, which could undergo redox reactions changing between Mn(II) and Mn(IV). The Mn 2p spectra exhibited distinct Mn 2p^1/2 and Mn 2p^3/2 peaks at 641 eV and 653 eV, respectively. The XPS spectra of the HYB-A film are shown in Figure 3. The oxidation number calculated from the O 1s spectra was identical to the one determined by the Mn 1s spectra. Furthermore, Figure 3c displays aan appearane of prominent hydration peak, indicating the presence of molecular water residue within the film structure, potentially facilitating the diffusion of electrolyte ions into the internal film structure.

図・表・数式 / Figures, Tables and Equations

Figure 1 FE-SEM image of (a) EPD-A, (b) EPD-S, (c) SIL-A, (d) SIL-S, (e) HYB-A, and (f) HYB-S

Figure 2. XPS spectra of Mn3s (a-d) and Mn2p (e-h) of MnO_x film.

Figure 3. XPS spectra of HYB-A film (a) Mn3s, (b) Mn2p, (c) O1s, and (d) survey scan.

その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)

This research was funded by the Office of National Higher Education Science Research and Innovation Policy Council (NXPO) grant number B05F630085 and King Mongkut’s Institute of Technology Ladkrabang (KMITL Doctoral Scholarship).

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)

1. Kanisorn Klangvijit, Control of Manganese Oxide Hybrid Structure through Electrodeposition and SILAR Techniques for Supercapacitor Electrode Applications, Coatings, 13, 1403(2023).
   DOI: https://doi.org/10.3390/coatings13081403
   

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