Currently, the most prevalent approach to preparing graphene is the oxidation of graphite to graphene oxide (GO) and the subsequent reduction of GO to reduced graphene oxide (rGO). Most reduction methods only focus on one-step reduction by either thermal annealing or chemical reduction. There is no conclusive understanding of which reduction method has advantages over the others. Here, using the same GO precursors, we systematically studied various reduction methods to achieve optimized electrochemical properties. We found that, to improve electrochemical properties of rGO, multiple-step reduction of GO was more effective compared to single-step methods including thermal annealing, microwave treatment, hydrazine reduction, and borohydride reduction. To evaluate the electrochemical performance, rGOs were studied using cyclic voltammetry to evaluate their electrochemically accessible surface area and double layer capacitance. Their steady-state oxygen reduction reaction (ORR) activities were compared in both acidic and alkaline electrolytes to study their potential as the components of ORR electrodes. Among these combinations, two-step borohydride and hydrazine reduction (rGO-NaBH₄-N₂H₄) with optimal sequence and conditions is able to completely recover the conjugated carbon structure with minimum defects, thus showing the best electrochemical properties. Importantly, extensive physical characterizations including XRD, Raman Spectroscopy, SEM, TEM, BET, and XPS are employed to compare the resulting rGOs in terms of their carbon structures, porosity, surface areas, defect content, and morphologies. These key structural and electrochemical properties of rGOs were found to be largely dependent on the permutation of reduction methods, in turn, affecting electrochemical properties. A correlation of reduction methods, structures, and properties is established to provide knowledge required for engineering rGO through tuning reduction conditions for optimal electrochemical properties for applications.

当前，制备石墨烯的最普遍的方法是将石墨氧化为氧化石墨烯（GO），然后将GO还原为还原的氧化石墨烯（rGO）。大多数还原方法仅集中于通过热退火或化学还原进行的一步还原。对于哪种还原方法比其他方法更具优势尚无定论。在这里，使用相同的GO前驱体，我们系统地研究了各种还原方法以实现最佳的电化学性能。我们发现，与包括热退火，微波处理，肼还原和硼氢化物还原的单步方法相比，GO的多步还原比单步方法更有效，从而改善了rGO的电化学性能。为了评估电化学性能，使用循环伏安法研究了rGO，以评估其电化学可及的表面积和双层电容。比较了它们在酸性和碱性电解液中的稳态氧还原反应（ORR）活性，以研究其作为ORR电极组件的潜力。在这些组合中，两步还原硼氢化物和肼（rGO-NaBH₄ -N ₂高₄）具有最佳的顺序和条件，能够以最少的缺陷完全恢复共轭碳结构，从而显示出最佳的电化学性能。重要的是，广泛的物理特征（包括XRD，拉曼光谱，SEM，TEM，BET和XPS）用于比较所得rGO的碳结构，孔隙率，表面积，缺陷含量和形态。发现rGO的这些关键结构和电化学性质在很大程度上取决于还原方法的排列，进而影响电化学性质。建立了还原方法，结构和性质的相关性，以通过调整还原条件以提供最佳的电化学性质为应用提供工程rGO所需的知识。