Mi Shuying, Cheng Na, Jiang Hao, Li Chunzhong, Jiang Haibo
Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology Shanghai 200237 P. R. China
RSC Adv. 2018 Apr 24;8(28):15344-15351. doi: 10.1039/c8ra02219d. eCollection 2018 Apr 23.
The size of nanocrystals (NCs) is regarded as one of the vital factors determining their electrochemical performance. To achieve high electrochemical activity and durability at the same time still remains a big challenge. This work has demonstrated the successful synthesis of PtNi nanocrystals of large size with porous characteristics (PNC-PtNi). The mass and specific activity of the as-prepared catalyst are 6 and 6.6 times more than those of commercial Pt/C at 0.9 volts the reversible hydrogen electrode (RHE), respectively. More importantly, PNC-PtNi prevails against a durability test (23.7% loss of mass activity after 10 000 potential cycling) with little change to the porous morphology under harsh experimental conditions. Density functional theory calculations show a much lower activation energy for PNC-PtNi during the process of dissociation of the oxygen molecule adsorbed on the surface of the catalyst, which may account for the improvement in the catalytic activity. The lower series resistance for PNC-PtNi is also verified by electrochemical impedance spectroscopy (EIS) data, resulting from fewer grain boundaries for nanocrystals with large sizes. This exciting work contributes a new strategy for the optimization of electrochemical performance and durability.
纳米晶体（NCs）的尺寸被视为决定其电化学性能的关键因素之一。要同时实现高电化学活性和耐久性仍然是一个巨大的挑战。这项工作展示了成功合成具有多孔特性的大尺寸PtNi纳米晶体（PNC-PtNi）。在相对于可逆氢电极（RHE）为0.9伏的条件下，所制备催化剂的质量活性和比活性分别是商业Pt/C的6倍和6.6倍。更重要的是，PNC-PtNi在耐久性测试中表现出色（在10000次电位循环后质量活性损失23.7%），在苛刻的实验条件下其多孔形态几乎没有变化。密度泛函理论计算表明，在吸附在催化剂表面的氧分子解离过程中，PNC-PtNi的活化能要低得多，这可能是催化活性提高的原因。电化学阻抗谱（EIS）数据也证实了PNC-PtNi的串联电阻较低，这是由于大尺寸纳米晶体的晶界较少所致。这项令人兴奋的工作为优化电化学性能和耐久性提供了一种新策略。
