Two-step model for reduction reaction of ultrathin nickel oxide by hydrogen

Ogawa, Shuichi*; Taga, Ryo*; Yoshigoe, Akitaka ; Takakuwa, Yuji*

Nickel (Ni) is used as a catalyst for nitric oxide decomposition and ammonia production but it is easily oxidized and deactivated. Clarification of the reduction process of oxidized Ni is essential to promote more efficient use of Ni catalysts. In this study, the reduction processes were investigated by in situ time-resolved photoelectron spectroscopy. We propose a two-step reduction reaction model. The rate-limiting process for the first step is surface precipitation of O atoms and that of the second step is dissociation of H molecules.