CAJ | 학술논문

基于密度泛函理论(DFT)设计了一系列不同氧化程度的还原氧化石墨烯片(rGNOs)并研究了其表面的氧化缺陷与吸附的氢氧化镍(Ni(OH)2)之间的相互作用。结果发现， rGNOs表面的含氧基团与Ni(OH)2之间的吸附能与含氧基团的氧化程度相关。在吸附Ni(OH)2后， rGNOs的原子间距和电荷分布的变化也都受rGNOs表面的含氧缺陷的氧化程度影响。理论计算的结果与实验观察的结果一致并能给出合理的解释。我们用简单的恒电位电化学沉积法有效地在rGNOs表面制备了粒径只有5 nm的Ni(OH)2纳米粒子。在Ni(OH)2/rGNOs制备过程中，氧化石墨烯的电化学还原是关键步骤。 Ni(OH)2上吸附的Ni(OH)2因具有更高的吸附能而使其与在镍膜表面直接吸附的Ni(OH)2(在5 mV?s-1下比电容为656 F?g-1)相比具有更高的比电容值(在5 mV?s-1下为1591 F?g-1)。 rGNOs在吸附Ni(OH)2后构型和电荷分布的变化导致Ni(OH)2具有更低的等效串联电阻和更佳的频率响应。 Ni(OH)2/rGNOs优异的赝电容特性表明其有潜力成为新型赝电容器材料。
기우밀도범함이론(DFT)설계료일계렬불동양화정도적환원양화석묵희편(rGNOs)병연구료기표면적양화결함여흡부적경양화얼(Ni(OH)2)지간적상호작용。결과발현， rGNOs표면적함양기단여Ni(OH)2지간적흡부능여함양기단적양화정도상관。재흡부Ni(OH)2후， rGNOs적원자간거화전하분포적변화야도수rGNOs표면적함양결함적양화정도영향。이론계산적결과여실험관찰적결과일치병능급출합리적해석。아문용간단적항전위전화학침적법유효지재rGNOs표면제비료립경지유5 nm적Ni(OH)2납미입자。재Ni(OH)2/rGNOs제비과정중，양화석묵희적전화학환원시관건보취。 Ni(OH)2상흡부적Ni(OH)2인구유경고적흡부능이사기여재얼막표면직접흡부적Ni(OH)2(재5 mV?s-1하비전용위656 F?g-1)상비구유경고적비전용치(재5 mV?s-1하위1591 F?g-1)。 rGNOs재흡부Ni(OH)2후구형화전하분포적변화도치Ni(OH)2구유경저적등효천련전조화경가적빈솔향응。 Ni(OH)2/rGNOs우이적안전용특성표명기유잠력성위신형안전용기재료。
We designed a series of models of reduced graphene oxide sheets (rGNOs) with different oxidation degrees and then studied the interactions between oxidation defects on rGNOs and nickel hydroxide (Ni(OH)2) using density functional theory (DFT). The adsorption energy between the oxygen-containing groups on rGNOs and Ni(OH)2 is dependent on the oxidation degree of rGNOs. The variations of atomic distances and charge distribution of the oxide-defected graphene after absorbing Ni(OH)2 suggested that the oxygen-containing groups on rGNOs improve the characteristics of Ni(OH)2 as a pseudocapacitor. These theoretical results agree wel with available experimental observations and give an explanation for some experimental results. We also introduce a simple potentiostatic electrodeposition method, with which Ni(OH)2 nanoparticles about 5 nm in diameter were effectively dispersed on the substrate via induction of oxidation defects on rGNOs. In the fabrication of Ni(OH)2/rGNOs, electrochemical reduction of graphene oxide is the key process. The stronger adsorption results in Ni(OH)2/rGNOs have higher rate pseudocapacitance (1591 F?g-1 at 5 mV?s-1) compared with that of Ni(OH)2 on bare nickel (656 F?g-1 at 5 mV?s-1). The variations of the geometries and charge distributions of the rGNOs after absorbing Ni(OH)2 lead to the lower equivalent series resistance and better frequency response of Ni(OH)2/rGNOs than Ni(OH)2/Ni. The high capacitance of Ni(OH)2/rGNOs indicates that Ni(OH)2/rGNOs have the potential of being used as the electrode material of pseudocapacitors.