Xiong Lixin, Ni Dixing, Xiong Wan, Wang Hewen, Ouyang Chuying
Department of Physics, Laboratory of Computational Materials Physics, Jiangxi Normal University, Nanchang, 330022, China.
Phys Chem Chem Phys. 2021 Feb 7;23(5):3588-3594. doi: 10.1039/d0cp05284a. Epub 2021 Feb 1.
The thermodynamics of phosphorus (P) doping to spinel CoO, for both bulk cases and (100) and (110) surface cases, is studied using first principles calculations. The doping energies of the P atom at different doping sites are carefully calculated and compared. It is shown that P doping at Co sites, at either tetrahedral or octahedral sites, is energetically favorable, while P doping and replacing O atoms are energetically unfavorable. The doping energy difference is large enough to conclude that P doping has a very strong preference to take the Co sites, rather than the O sites in spinel CoO. Even when O-vacancy is available, P doping and taking the O-vacancy site is thermodynamically unfavorable. The physical/chemical mechanism behind this phenomenon is carefully analyzed. Electronic structure analysis shows that P doping and replacing the Co atom brings excess electrons to the CoO system, which is beneficial to enhance the electrochemical and catalytic performance of the spinel CoO. Our results clarified the misleading results of P doping and replacing O atoms in spinel CoO reported in the literature.
采用第一性原理计算方法，研究了磷（P）掺杂到尖晶石CoO体相、（100）和（110）表面的热力学性质。仔细计算并比较了P原子在不同掺杂位点的掺杂能。结果表明，P在Co位点（四面体或八面体位点）的掺杂在能量上是有利的，而P掺杂并取代O原子在能量上是不利的。掺杂能的差异足够大，足以得出结论：在尖晶石CoO中，P掺杂非常倾向于占据Co位点，而不是O位点。即使存在氧空位，P掺杂并占据氧空位在热力学上也是不利的。对这一现象背后的物理/化学机制进行了仔细分析。电子结构分析表明，P掺杂并取代Co原子会给CoO体系带来多余的电子，这有利于提高尖晶石CoO的电化学和催化性能。我们的结果澄清了文献中报道的关于P掺杂并取代尖晶石CoO中O原子的误导性结果。
