Effects of rare earth metal doping on Au/ReZrO2 catalysts for efficient hydrogen generation from formic acid

Abstract

Formic acid (FA) as a safe and promising hydrogen carrier has attracted widespread attention. The use of solid catalysts in the controllable and efficient dehydrogenation of FA is still a challenge. Here, a series of Au nanoclusters supported on rare earth metal doped ZrO₂ catalysts (Au/ReZrO₂ (Re = Nd, Ce and Sm)) was prepared. Doping rare earth metals in zirconia stabilizes the mixed-phase zirconia into the tetragonal phase. Meanwhile, the rare earth metal dopants can promote the formation of oxygen vacancies in zirconia, which promotes charge transfer from the support to Au and enhances the metal–support interaction on all the three catalysts. As a result, Au/ReZrO₂ (Re = Nd³⁺, Ce³⁺ and Sm³⁺) catalysts exhibited better catalytic performance in the liberation of CO-free H₂ from FA, outperforming Au supported on primary ZrO₂. Structural and electronic characterization by XPS and H₂-TPR further confirmed the contribution of doping rare earth metal cations in Au/ReZrO₂, which can enhance the metal–support interaction and accelerate the decomposition of HCOOH into H₂, thus resulting in the improvement in catalytic activity for hydrogen production from FA.