CeO₂具有良好的赝电容, 但有关碳/CeO₂复合材料的电化学性能有待改善. 本工作采用简单的微波辅助合成法, 将氧化石墨烯与Ce(NO₃)₃混合发生氧化还原反应, 获得还原氧化石墨烯(rGO)/CeO₂复合材料. 通过形貌观察, CeO₂以颗粒形式均匀分布在褶皱的rGO上, 且沿着rGO表面仿形生长; 纳米级CeO₂颗粒之间存在微小间隙. N₂吸/脱附测试结果表明, rGO/CeO₂具有大的比表面积和介孔孔径, 有益于与电解液充分接触. 通过电化学测试, rGO/CeO₂的比电容高达468 F•g^-1, 经过10000次充放电循环, 电容保持率高达107.3%. 优异的循环稳定性归因于大表面积的rGO与均匀薄层的CeO₂良好的协同效应减少了离子传输的阻力以及CeO₂颗粒之间微小的间隙, 缓解了Ce⁴⁺还原为Ce³⁺过程中发生的晶格膨胀. 将rGO/CeO₂组装成对称型超级电容器rGO/CeO₂||rGO/CeO₂获得的能量密度达18.16 Wh•kg^-1. rGO/CeO₂作为超级电容器电极材料具有广阔前景.

CeO₂ possesses excellent pseudocapacitance, nevertheless the electrochemical properties of carbon/CeO₂ composites need to be improved. In this paper, reduced graphene oxide (rGO)/CeO₂ composite is prepared via a simple microwave-assisted synthesis method. The typical synthesis process is as follows. Firstly, 60 mg of graphene oxide was dissolved into 50 mL of deionized water. Then 20 mL of 0.17 mol•L^-1 Ce(NO₃)₃•6H₂O solution was added under ultrasonic conditions. The electrostatic assembly led to the combination of the graphene oxide and Ce(NO₃)₃. Afterwards, 10 mL of 1.5 mol•L^-1 KOH was added dropwise into the mixed solution until the pH value up to 10. The rGO/CeO₂ was synthesized in the above-mentioned mixed solution by using the microwave heating method. The heating time was set for 45 s. Repeated the microwave heating process for five times after the solution cooled down to the room temperature. Finally, the rGO/CeO₂ was harvested by centrifugation, washing and freeze-drying. The CeO₂, in the form of particles, distributes uniformly and conformally on the surface of the corrugated rGO by the morphology observation. The existence of the tiny gaps is displayed between the nano-scaled CeO₂ particles. N₂ adsorption/desorption analysis suggests that the rGO/CeO₂ has large specific area and pores in the mesoporous size, which is helpful to the sufficient contact with the electrolyte. By the electrochemical measurements, the specific capacitance of the rGO/CeO₂ is as high as 468 F•g^-1 and the capacity retention is up to 107.3% after 10000 charge/discharge cycles. The excellent cycling stability is attributed to the good synergistic effect between the rGO with large specific area and the CeO₂ with uniform and thin layer, which decreases the resistance of ion transport, and the tiny gaps between CeO₂ particles, which mitigates the lattice expansion during the transformation from Ce⁴⁺ to Ce³⁺. The energy density of the assembled symmetrical supercapacitor rGO/CeO₂||rGO/CeO₂ reaches 18.16 Wh•kg^-1. As a supercapacitor electrode material, the rGO/CeO₂ has wide prospect.