title: OER activity manipulated by IrO6coordination geometry: an insight from pyrochlore iridates.
abstract: The anodic reaction of oxygen evolution reaction (OER), an important point for electrolysis, however, remains the obstacle due to its complicated reaction at electrochemical interfaces. Iridium oxide (IrO2) is the only currently known 5d transition metal oxide possessing admirable OER activity. Tremendous efforts have been carried out to enhance the activity of iridium oxides. Unfortunately there lies a gap in understanding what factors responsible for the activity in doped IrO2or the novel crystal structure. Based on two metallic pyrochlores (Bi2Ir2O7and Pb2Ir2O6.5) and IrO2. It has been found that there exists a strong correlation between the specific OER activity and IrO6coordination geometry. The more distortion in IrO6geometry ascends the activity of Ir sites, and generates activity order of Pb-Ir > IrO2> Bi-Ir. Our characterizations reveal that distorted IrO6in Pb-Ir induces a disappearance of J = 1/2 subbands in valence band, while Bi-Ir and IrO2resist this nature probe. The performed DFT calculations indicated the distortion in IrO6geometry can optimize binding strength between Ir-5d and O-2p due to broader d band width. Based on this insight, enhancement in OER activity is obtained by effects that change IrO6octahedral geometry through doping or utilizing structural manipulation with nature of distorted octahedral coordination.
authors.affiliation: 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.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.affiliation: 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.
authors.forename: Ji-Yuan
authors.initials: JY
authors.lastname: Liu
authors.affiliation: 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.
authors.forename: Xue-Qing
authors.initials: XQ
authors.lastname: Gong
authors.affiliation: 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.
authors.forename: Waqas-Qamar
authors.initials: WQ
authors.lastname: Zaman
authors.affiliation: 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.
authors.forename: Li-Mei
authors.initials: LM
authors.lastname: Cao
authors.affiliation: 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.
authors.forename: Ji
authors.initials: J
authors.lastname: Yang