A surface sensitive hard X-ray spectroscopic method applied to observe the surface layer reduction reaction of Co...

A simple and easy surface sensitive spectroscopic method using hard X-rays has been developed and applied to observe the surface oxide reduction reaction. The method named TREXS, Total REflection X-ray Spectroscopy, records the total reflection of incident X-rays at sample surfaces. The surface reduction reaction of Co oxide (Co₃O₄) to Co metal was successfully observed by in situ TREXS measurements with a surface sensitivity of ∼2 nm. The in situ TREXS measurements were performed under H₂ flow of N₂ balanced atmospheric pressure with increasing temperature. This method, in situ TREXS, will be a suitable and powerful tool to observe a variety of surface chemical reactions and consequently to understand catalytic processes under realistic operating conditions.