纳米ZrO2在O2/H2气中的表面效应

用ESR方法研究了一种纳米ZrO₂在普通H₂气中升温条件下的表面效应.ZrO₂上Zr³⁺的中心量约为1×10^-7mol/g.这些Zr³⁺中心是ZrO₂表面一些O^2-配位不饱和的Zr原子点位.在普通H₂气中,ZrO₂上的Zr³⁺中心数在温度低于400℃时变化很小.但在这一温度范围内从室温升温时,由ZrO₂表面羟基的H₂还原引起的F中心量随温度的升高而增加.温度高于400℃时,ZrO₂表面的Zr³⁺及F中心可与普通H₂气中存在的少量O₂气作用产生O₂^-,并伴随ZrO₂表面羟基的脱除而形成新的Zr³⁺.

Surface Effect of ZrO2 Nanopowder in O2/H2

Akind of ZrO₂ nanopowder annealed at different temperatures in H₂ has been studied by ESR. On the surface of ZrO₂, about 1×10^-7 mol/g of Zr³⁺ centers are detected, which are the oxygen coordinatively unsaturated Zr. When the annealing temperature is lower than 400℃, the amount of Zr³⁺ center remains almost unchanged, while the amount of F-center increases in this temperature range, which may be resulted from the reduction of surface hydroxyl by H₂. When the annealing temperature is higher than 400℃, O₂^- is originated on the surface of ZrO₂, which may be formed from the reaction of Zr³⁺ and F-center with the trace amount of O₂ in ordinary H₂, and simultaneously, some Zr³⁺ centers are created, as being accompanied with the removal of surface hydroxyl.