Ir0.89Ni0.11水合氧化物纳米颗粒电催化水氧化机理研究

Mechanistic study of Ir0.89Ni0.11 and Ir hydrous oxide nanoparticles for water oxidation reaction

Ir0.89Ni0.11水合氧化物纳米颗粒(Ir0.89Ni0.11 HO-np)可应用于质子交换膜水电解槽.HR-TEM和XRD表明Ir 0.89Ni0.11 HO-np由纳米晶相组成,且这些水合氧化物纳米颗粒与IrO2结构类似.XPS表明当Ni掺杂到晶格中时,铱的电子密度增加,并且有Ni-O-Ir的结构形成.电化学研究证明在Ir0.89Ni0.11HO-np上观察到的水氧化活性的增强是由于Ir-OH中间体与表面Ni-O的协同作用导致了水氧化反应的活化焓降低.Tafel分析和动力学同位素效应都表明Ir和Ir0.89Ni0.11HO-np的速率决定步骤是表面-OH中间体的重排.

Ir0.89 Ni0.11 hydrous oxide nanoparticles(HO-np)can be applied in polymer electrolyte membrane water electrolyzers.High resolution transmission spectroscopy reveals that the Ir0.89Ni0.11 HO-np constitutes with small crystalline phases,and X-ray diffraction shows the hydrous nanoparticles has a similar structure with IrO2.X-ray photoelectron spectroscopy indicates increased electron density at Ir site and the formation Ni-O-Ir motif when doping Ni into the lattice.Electrochemical study implies that the enhanced water oxidation activity observed at Ir0.89Ni0.11 HO-np are likely attributed to the interaction of Ir-OH intermediates with the Ni-O at the surface,leading to decreased enthalpy of activation for water oxidation reaction.Both Tafel analysis and secondary kinetic isotope effect supported the proposal that the rate determining step on Ir and Ir 0.89 Ni 0.11 HO-np is the rearrangement of surface hydroxide intermediate.