Sun Wei, Song Ya, Gong Xue-Qing, Cao Li-Mei, Yang Ji
State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Processes , School of Resources and Environmental Engineering East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , P. R. China . Email:
Key Laboratory for Advanced Materials , Center for Computational Chemistry and Research Institute of Industrial Catalysis , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , P. R. China . Email:
Chem Sci. 2015 Aug 1;6(8):4993-4999. doi: 10.1039/c5sc01251a. Epub 2015 Jun 12.
The oxygen evolution reaction (OER) has been regarded as a key half reaction for energy conversion technologies and requires high energy to create O[double bond, length as m-dash]O bonds. Transition metal oxides (TMOs) seem to be a promising and appealing solution to the challenge because of the diversity of their d-orbital states. We chose IrO as a model because it is universally accepted as a current state-of-the-art OER catalyst. In this study, copper-doped IrO, particularly CuIrO , is shown to significantly improve the OER activity in acidic, neutral and basic solutions compared to un-doped IrO. The substituted amount of Cu in IrO has a limit described by the CuIrO composition. We determined that the performance of CuIrO is due primarily to an increase in the Jahn-Teller effect in the CuO octahedra, and partially to oxygen defects in the lattice induced by the IrO octahedral geometric structure distortions, which enhance the lift degeneracy of the t and e orbitals, making the d orbital partially occupied. This phenomenon efficiently reduces the difference between Δ2 and Δ3 in the free energy from the density functional theoretical (DFT) calculations and can yield a lower theoretical overpotential comparable to that of IrO. The proposed method of doping with foreign elements to tune the electron occupation between the t and e orbital states of Ir creates an opportunity for designing effective OER catalysts using the TMO groups.
析氧反应（OER）被视为能量转换技术中的关键半反应，形成O=O键需要高能量。过渡金属氧化物（TMOs）因其d轨道状态的多样性，似乎是应对这一挑战的一种有前景且有吸引力的解决方案。我们选择IrO作为模型，因为它被普遍认为是当前最先进的析氧反应催化剂。在本研究中，与未掺杂的IrO相比，铜掺杂的IrO，特别是CuIrO，在酸性、中性和碱性溶液中均显示出显著提高的析氧反应活性。IrO中Cu的取代量有一个由CuIrO组成所描述的限度。我们确定CuIrO的性能主要归因于CuO八面体中 Jahn-Teller 效应的增强，部分归因于由IrO八面体几何结构畸变引起的晶格中的氧缺陷，这增强了t和e轨道的简并度提升，使d轨道部分占据。这种现象有效地减小了密度泛函理论（DFT）计算中自由能的Δ2和Δ3之间的差异，并能产生与IrO相当的较低理论过电位。所提出的通过掺杂外来元素来调节Ir的t和e轨道态之间电子占据的方法，为使用TMO基团设计有效的析氧反应催化剂创造了机会。
