Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Seri Iskandar, Perak, Malaysia.
Centre of Innovative Nanostructures and Nanodevices (COINN), Universiti Teknologi PETRONAS, Seri Iskandar, Perak, Malaysia.
PLoS One. 2020 Feb 3;15(2):e0228322. doi: 10.1371/journal.pone.0228322. eCollection 2020.
This study investigates the effects of stirring duration on the synthesis of graphene oxide (GO) using an improved Hummers' method. Various samples are examined under different stirring durations (20, 40, 60, 72, and 80 h). The synthesized GO samples are evaluated through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The GO sample with 72 h stirring duration (GO72) has the highest d-spacing in the XRD results, highest atomic percentage of oxygen in EDX (49.57%), highest intensity of oxygen functional group in FTIR spectra, and highest intensity ratio in Raman analysis (ID/IG = 0.756). Results show that GO72 with continuous stirring has the highest degree of oxidation among other samples. Electrochemical impedance spectroscopy analysis shows that GO72-titanium dioxide (TiO2) exhibits smaller charge transfer resistance and higher electron lifetime compared with the TiO2-based photoanode. The GO72 sample incorporating TiO2 nanocomposites achieves 6.25% photoconversion efficiency, indicating an increase of more than twice than that of the mesoporous TiO2 sample. This condition is fully attributed to the efficient absorption rate of nanocomposites and the reduction of the recombination rate of TiO2 by GO in dye-sensitized solar cells.
本研究采用改良的 Hummers 法考察了搅拌时间对氧化石墨烯（GO）合成的影响。在不同的搅拌时间（20、40、60、72 和 80 h）下对各种样品进行了检查。通过 X 射线衍射（XRD）、场发射扫描电子显微镜（FESEM）、能量色散光谱（EDX）、傅里叶变换红外光谱（FTIR）和拉曼光谱对合成的 GO 样品进行了评估。在 XRD 结果中，搅拌时间为 72 h 的 GO 样品（GO72）具有最高的层间距，EDX 中氧的原子百分比最高（49.57%），FTIR 光谱中氧官能团的强度最高，拉曼分析中的强度比（ID/IG = 0.756）最高。结果表明，在其他样品中，连续搅拌的 GO72 具有最高的氧化程度。电化学阻抗谱分析表明，与 TiO2 基光阳极相比，GO72-二氧化钛（TiO2）表现出更小的电荷转移电阻和更高的电子寿命。GO72 样品中掺入 TiO2 纳米复合材料的光转换效率达到 6.25%，表明比介孔 TiO2 样品增加了两倍以上。这种情况完全归因于纳米复合材料的高效吸收率以及 GO 在染料敏化太阳能电池中对 TiO2 的复合率的降低。
