通过交替微波法制备了 PdxNi/C (x = 1~4) 催化剂, 并对其形貌、结构及电化学性能进行了表征. 结果表明, 通过在 Pd 中掺杂 Ni 原子, 其对氧还原反应 (ORR) 的催化活性较纯 Pd 的高. 同时采用密度泛函理论 (DFT) 计算了一系列简化的团簇模型. 计算结果表明, 随着 Ni 的加入, 纳米颗粒的最高占据轨道 (HOMO) 与最低空轨道 (LUMO) 能级增加, 且两能级间隙 (HLG) 减小. 因此在 ORR 中, 一方面由于 LUMO 被抬高, 降低了电子亲和能, 带负电的催化剂颗粒更易将电子传递给 O2, 另一方面由于 HLG 减小, 电中性颗粒 HOMO 上的电子也容易失去. 这两方面的作用使其对O2 还原活性得以增强. Fukui 指数结合 DFT 方法和 Mulliken 布居分析指出, 表面的 Pd 原子为催化剂团簇的活性中心
The PdxNi/C (x =1-4) catalysts were synthesized by an intermittent microwave method. The structure, morphology, and electrochemical performance were investigated. The results showed that the performance of the pure Pd for oxygen reduction reaction (ORR) could be improved by doping with Ni. The mechanism was studied by density functional theory (DFT) based on a serial of cluster models. The calculated results showed that the energy levels of HOMO and LUMO of the pure Pd nanoparticles were commonly uplifted by adding Ni atoms into them, and the energy gaps between the two orbitals were shortened. These changes made it easier for passing their electrons to O2 in ORR on PdxNi/C catalysts. The activity centers of cluster are Pd atoms on the surface according to the calculation of Fukui index, which combines with DFT results and Mulliken population analysis.