Pristine ZnO and Mn doped ZnO (Mn-ZnO) were synthesized by sol–gel auto-combustion method. Three different concentrations of Mn-ZnO (1%, 5%, and 10%) were treated with rGO in hydrothermal reactor to obtained (1%, 5%, and 10%) Mn-ZnO@rGO nanocomposites. X-ray diffraction (XRD) pattern confirmed the successful incorporation of Mn into the ZnO lattice and the formation of Mn-ZnO@rGO nanocomposites. The peak at 2θ = 25.16° signifies the presence of reduced graphene oxide (rGO) thus confirmed formation of Mn-ZnO@rGO nanocomposite. Rietveld refined pattern showed that all the samples are pure with wurtzite structure. The Fourier-transform infrared (FTIR) spectroscopy revealed the presence of metal–oxygen bonds and functional groups within the composites. The stretching vibration of ZnO at 464 cm−1 confirmed the wurtzite structure. The peak at 600 cm−1 and 880 cm−1 assigned for vibrational, antisymmetric stretching mode of MnO and Mn–O respectively. Significant peaks at 1080 cm−1 and 1392 cm−1 are due to C-O stretching vibrations from C–O–C bonds and C–OH bending vibrations, respectively. The peak at 1432 cm−1 indicates the -C = O group stretching vibration from inorganic carbonate species. The peak at 2850 cm−1 corresponds to the symmetrical stretching vibration of the C-H group. FTIR analysis confirmed formation of Mn-ZnO@rGO nanocomposite. Field emission scanning electron microscopy (FESEM) images demonstrate a high density of irregularly sized nanoparticles, confirming the effective deposition of Mn-ZnO nanoparticles on to rGO sheets and the robust binding of these nanoparticles, resulting in Mn-ZnO@rGO nanocomposites. X-ray photoelectron spectroscopy (XPS) provided detailed insights into the oxidation states of the elements with a focus on 5% Mn-ZnO@rGO nano composite. The survey spectrum for the 5% Mn-ZnO@rGO nanocomposite confirmed the presence of Zn, Mn, O, and C. The lack of contaminants peaks in the XPS analysis supports the successful synthesis of Mn-ZnO@rGO nanocomposite. Raman spectroscopy detected vibrational modes between 1300 cm⁻1 and 1600 cm⁻1, which are characteristic of rGO and Mn-ZnO@rGO nanocomposites. There is increase in the D band and G band intensity ratio (ID/IG), and this confirms the disorder in the carbon components. It further confirmed that during the Mn-ZnO@rGO composite's formation, GO was converted to rGO. Electrochemical performance, assessed through Electrochemical Impedance Spectroscopy (EIS), Galvanostatic Charge–Discharge (GCD), and Cyclic Voltammetry (CV). Long-term cycling stability over 5000 cycles indicated that 5% Mn-ZnO@rGO nanocomposite exhibited superior performance compared to 1% and 10% counterparts. Additionally, photoelectrochemical cell (PEC) measurements further validated the exceptional performance of the 5% Mn-ZnO@rGO nanocomposite. These findings demonstrate that the 5% Mn-ZnO@rGO nanocomposite is a highly promising material for supercapacitor and PEC applications.

Optimized Mn doped ZnO@rGO nanocomposites: a breakthrough for advanced energy storage and PEC systems

期刊论文
发表日期：

2025年6月16日

查看全文

Zarina Ansari,
Suresh Kadam,
Sujata Kasabe,
Jenis Tripathi,
Pramod Agale,
Sunil Patange,
Paresh More

摘要

Pristine ZnO and Mn doped ZnO (Mn-ZnO) were synthesized by sol–gel auto-combustion method. Three different concentrations of Mn-ZnO (1%, 5%, and 10%) were treated with rGO in hydrothermal reactor to obtained (1%, 5%, and 10%) Mn-ZnO@rGO nanocomposites. X-ray diffraction (XRD) pattern confirmed the successful incorporation of Mn into the ZnO lattice and the formation of Mn-ZnO@rGO nanocomposites. The peak at 2θ = 25.16° signifies the presence of reduced graphene oxide (rGO) thus confirmed formation of Mn-ZnO@rGO nanocomposite. Rietveld refined pattern showed that all the samples are pure with wurtzite structure. The Fourier-transform infrared (FTIR) spectroscopy revealed the presence of metal–oxygen bonds and functional groups within the composites. The stretching vibration of ZnO at 464 cm⁻¹ confirmed the wurtzite structure. The peak at 600 cm⁻¹ and 880 cm⁻¹ assigned for vibrational, antisymmetric stretching mode of MnO and Mn–O respectively. Significant peaks at 1080 cm⁻¹ and 1392 cm⁻¹ are due to C-O stretching vibrations from C–O–C bonds and C–OH bending vibrations, respectively. The peak at 1432 cm⁻¹ indicates the -C = O group stretching vibration from inorganic carbonate species. The peak at 2850 cm⁻¹ corresponds to the symmetrical stretching vibration of the C-H group. FTIR analysis confirmed formation of Mn-ZnO@rGO nanocomposite. Field emission scanning electron microscopy (FESEM) images demonstrate a high density of irregularly sized nanoparticles, confirming the effective deposition of Mn-ZnO nanoparticles on to rGO sheets and the robust binding of these nanoparticles, resulting in Mn-ZnO@rGO nanocomposites. X-ray photoelectron spectroscopy (XPS) provided detailed insights into the oxidation states of the elements with a focus on 5% Mn-ZnO@rGO nano composite. The survey spectrum for the 5% Mn-ZnO@rGO nanocomposite confirmed the presence of Zn, Mn, O, and C. The lack of contaminants peaks in the XPS analysis supports the successful synthesis of Mn-ZnO@rGO nanocomposite. Raman spectroscopy detected vibrational modes between 1300 cm⁻¹ and 1600 cm⁻¹, which are characteristic of rGO and Mn-ZnO@rGO nanocomposites. There is increase in the D band and G band intensity ratio (ID/IG), and this confirms the disorder in the carbon components. It further confirmed that during the Mn-ZnO@rGO composite's formation, GO was converted to rGO. Electrochemical performance, assessed through Electrochemical Impedance Spectroscopy (EIS), Galvanostatic Charge–Discharge (GCD), and Cyclic Voltammetry (CV). Long-term cycling stability over 5000 cycles indicated that 5% Mn-ZnO@rGO nanocomposite exhibited superior performance compared to 1% and 10% counterparts. Additionally, photoelectrochemical cell (PEC) measurements further validated the exceptional performance of the 5% Mn-ZnO@rGO nanocomposite. These findings demonstrate that the 5% Mn-ZnO@rGO nanocomposite is a highly promising material for supercapacitor and PEC applications.