Xia Zhiyuan, Zhu Xiangyu, Chen Xing, Zhou Yanan, Luo Qiquan, Yang Jinlong
Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, China.
School of Material Science and Chemical Engineering, Ningbo University, Ningbo 315211, China.
J Phys Chem Lett. 2024 Sep 26;15(38):9566-9574. doi: 10.1021/acs.jpclett.4c02164. Epub 2024 Sep 12.
Unveiling the composition-dependent catalytic mechanism of Pt-based alloy cathodes for the oxygen reduction reaction (ORR) helps improve the proton exchange membrane fuel cells. Using density functional theory calculations, this study investigates the ORR catalytic performance of the Pt-Ni system with various compositions (1.00, ∼0.99, 0.75, 0.50, 0.25, ∼0.01, and 0.00). The ordered solid solution PtNi(111) system shows activity comparable to Pt(111) and is cost-effective. The Ni/Pt(111) system, featuring a single Ni atom on the Pt(111) surface as a surface single-atom alloy (SSAA), demonstrates the highest activity with an overpotential of only 0.28, which could be further reduced to 0.21 V by decreasing the surface Ni concentration to 1/16 monolayer coverage. The predicted high activity of Ni/Pt(111) is confirmed when considering factors such as the implicit solution environment, constant potential conditions, and protonation capability. Moreover, surface-adsorbed oxygen species driven by reaction conditions stabilize these single Ni atoms of Ni/Pt(111) by preventing segregation and dissolution processes, thereby exhibiting a dual functionality. This study reveals the composition dependence of Pt-based alloys and highlights the stability mechanisms of SSAA catalysts during the ORR.
揭示用于氧还原反应（ORR）的铂基合金阴极的成分依赖性催化机制有助于改进质子交换膜燃料电池。本研究使用密度泛函理论计算，研究了具有不同成分（1.00、0.99、0.75、0.50、0.25、0.01和0.00）的Pt-Ni体系的ORR催化性能。有序固溶体PtNi(111)体系表现出与Pt(111)相当的活性，且具有成本效益。Ni/Pt(111)体系在Pt(111)表面具有单个Ni原子，作为表面单原子合金（SSAA），表现出最高的活性，过电位仅为0.28，通过将表面Ni浓度降低到1/16单层覆盖度，过电位可进一步降低到0.21V。考虑到隐式溶液环境、恒电位条件和质子化能力等因素时，Ni/Pt(111)预测的高活性得到证实。此外，反应条件驱动的表面吸附氧物种通过防止偏析和溶解过程稳定了Ni/Pt(111)的这些单个Ni原子，从而表现出双重功能。本研究揭示了铂基合金的成分依赖性，并突出了ORR过程中SSAA催化剂的稳定性机制。
