Formic Acid Dehydrogenation on Ni(111) and Comparison with Pd(111) and Pt(111)

Abstract

Spin-polarized density functional theory calculations have been performed to investigate formic acid dehydrogenation into carbon dioxide and hydrogen (HCO2H → CO2 + H2) on Ni(111). It is found that formic acid prefers the O (O═C) atop adsorption on nickel surface and the H (H–O) atom bridging two neighboring nickel atoms, and formate prefers the bidentate adsorption with O atop on nickel surface. The computed stretching frequencies for deuterated formic acid (DCO2H) and deuterated formate (DCO2) on Ni(111) agree well with the experimentally observed IR spectra. Formic acid dehydrogenation into surface formate and hydrogen atom (HCO2H → HCO2 + H) has barrier of 0.41 eV and is exothermic by 0.35 eV. Formate dehydrogenation into carbon dioxide and hydrogen atom (HCO2 → CO2 + H) has an effective barrier of about 1.0 eV and is the rate-determining step. Our computed adsorption configurations and energetic data for formic acid dehydrogenation on Ni(111) are very close to the reported results for Pt(111), but in sharp contrast to the previously reported results for Pd(111). Our recalculated adsorption configurations and energetic data for formic acid dehydrogenation on Pd(111) are similar to those on Ni(111) and Pt(111), demonstrating the high similarities of these metals. These computed data show that Pd-catalyzed formic acid dehydrogenation has the lowest effective barrier (0.76 eV), followed by Ni (1.03 eV) and Pt (1.56 eV).