68-Atom gold nanoparticles (Au₆₈) were adsorbed on fractured carbon nanotubes by acid treatment to obtain an active catalyst (Au₆₈–CNT) for the oxygen reduction reaction (ORR). TEM images show the importance of acid treatment to create defects on the walls of the CNT, where Au₆₈ would then adsorb. X-Ray photoelectron spectroscopy confirmed that the Au₆₈ surface is exclusively composed of metallic gold when at the surface of CNT. FTIR characterization showed the presence of 4-mercapto-benzoic acid residues, which are necessary for the synthesis and are then removed through electrochemical reduction. The electrocatalytic studies were conducted in an alkaline medium, where Au₆₈–CNT proved to be an efficient catalyst for the ORR with the transfer of 3.9 electrons for direct water production. In acidic medium, poor performance and stability were observed. Durability tests were conducted by performing 5000 accelerated cyclic voltammograms, during which the half-wave potential of the polarization curve for the ORR decreased only by 20 mV. The DFT calculations were performed to simulate the interactions between O₂ and Au₆₈–CNT, and energy barriers, using the NEB method for O₂ dissociation and contrasting values with Au (111), Au (110), Au (100), and Pt₆₈–CNT. Large energy barriers indicating low ORR activity were obtained at surfaces different from Au₆₈–CNT and Pt₆₈–CNT. O₂ would bind to four Au atoms in Au68–CNT with a binding energy of −0.56 eV. The reactivity of Au₆₈–CNT for ORR would be associated with the irregular geometry of the Au₆₈ surface.

中文翻译：

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碳纳米管支撑的 68 原子金簇上的氧还原反应：理论和实验分析

通过酸处理将68 原子金纳米粒子 (Au ₆₈ ) 吸附在断裂的碳纳米管上，以获得用于氧还原反应 (ORR)的活性催化剂 (Au ₆₈ -CNT)。TEM 图像显示了酸处理在 CNT 壁上产生缺陷的重要性，然后Au ₆₈将吸附在那里。X 射线光电子能谱证实，当位于 CNT 表面时，Au ₆₈表面仅由金属金组成。FTIR 表征表明存在 4-巯基苯甲酸残基，这是合成所必需的，然后通过电化学还原被去除。电催化研究是在碱性介质中进行的，其中 Au ₆₈–CNT 被证明是 ORR 的有效催化剂，可转移 3.9 个电子用于直接产水。在酸性介质中，观察到较差的性能和稳定性。耐久性测试通过执行 5000 次加速循环伏安图进行，在此期间 ORR 极化曲线的半波电位仅降低了 20 mV。执行 DFT 计算以模拟 O ₂和 Au ₆₈ –CNT之间的相互作用以及能量势垒，使用 NEB 方法进行 O ₂解离，并将值与 Au (111)、Au (110)、Au (100) 和Pt ₆₈ –CNT。在不同于 Au ₆₈ –CNT 和 Pt _{68 的}表面上获得了表明 ORR 活性低的大能量势垒-CNT。O ₂将以-0.56 eV 的结合能与Au68-CNT 中的四个Au 原子结合。Au ₆₈ -CNT 对 ORR的反应性与 Au ₆₈表面的不规则几何形状有关。