Local Coordination and Ordering Engineering to Design Efficient Core-Shell Oxygen Reduction Catalysts
Local Coordination and Ordering Engineering to Design Efficient Core-Shell Oxygen Reduction Catalysts
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DOI：
10.1149/1945-7111/abc1a5
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发表时间：
2020-10
影响因子：
3.9
通讯作者：
Hengquan Chen;Tianlong Zheng;Qinggang He;Long Shang;Guangjin Wang;Qi Wang;Xiaojiang Wang;Xiaobo Shi;Meng Gu;Zheng Jiang
中科院分区：
文献类型：
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作者：
Hengquan Chen;Tianlong Zheng;Qinggang He;Long Shang;Guangjin Wang;Qi Wang;Xiaojiang Wang;Xiaobo Shi;Meng Gu;Zheng Jiang
对于大多数核壳纳米结构的铂基合金电催化剂，表面铂层的局域环境和构型是随机产生的，这将阻碍铂原子利用率、活性和稳定性的进一步提高。在这里，我们选择了不同结构有序的AuCu合金作为衬底，通过用铂原子取代铜的精确控制，在其表面沉积了一层铂壳。各种物理和电化学表征表明，由于表面原子的重排，AuCu芯的结构有序性会影响表面铂原子的分布。优化后的催化剂对氧还原反应具有较高的质量活性(0.75A·mg铂−1)和比活性(0.491 mA·cm铂−2)，分别是商用铂/碳催化剂的7.5倍和3.6倍。此外，经过10,000次加速耐久性试验(ADTS)后，催化剂还具有很高的稳定性，活性衰减可以忽略不计。密度泛函理论(DFT)计算表明，与随机分布相比，精确控制的铂局部环境可以更大程度地降低ORR速率决定步骤的吉布斯自由能垒，从而提高催化剂的催化性能。
For most core–shell nanostructured Pt-based alloy electrocatalysts, the local environment and configuration of surface Pt layers are randomly generated, which would hinder the further improvement of the utilization, activity and stability of Pt atoms. Herein, we have selected AuCu alloys with different structural ordering as substrates and deposited a Pt shell on their surface via the precise control of replacing Cu with Pt atoms. Various physical and electrochemical characterizations indicate that the structural ordering of an AuCu core could influence the distribution of surface Pt atoms due to the rearrangement of surface atoms. After optimization, the obtained catalysts displayed a high mass activity (0.75 A· mg Pt− 1) and specific activity (0.491 mA· cm Pt− 2) for the oxygen reduction reaction (ORR), which were nearly 7.5 times and 3.6 times those of commercial Pt/C, respectively. In addition, the catalysts could also exhibit a high stability with a negligible activity decay after 10,000 cycles of accelerated durability tests (ADTs). The density functional theory (DFT) calculation reveals that the precisely controlled Pt local environment could lower the Gibbs free energy barrier for the rate-determining step of ORR more than a random distribution could, thus enhancing the catalytic performance of the prepared catalysts.