Effects of Alloyed Metal of Cu3X(111) on Controlling O-H and α-C-H Bond Cleavages for Ethanol Dehydrogenation (X=Zr, In, Ag, Au)

Economically advantageous Cu-based catalysts have been widely used for a great number of reactions related to ethanol. However, serious obstacles still remain, such as the high reaction energy barrier and low selectivity for the first step of the dehydrogenation of ethanol. In this study, O-H and α-C-H bond cleavages in ethanol on a Cu3X(111) surface (X= Zr, In, Ag, Au) were carried out using DFT to explore the effect of alloying on the selective and effective dehydrogenation of ethanol. Cu3Zr(111) was found to have superior catalytic performances for dehydrogenation with significantly low reaction barriers for both O-H bond cleavage (0.13 eV) and α-C-H bond cleavage (0.73 eV), which are much lower than the results on Cu(111). Thus this work indicates that alloying Zr can selectively break the O-H bond of ethanol, which cannot be accomplished using Pt, Pd, or Cu catalysts. Meanwhile, through PDOS analysis, Mülliken charge analysis, and d-band center analysis, there are two key fac-tors that contribute to the great improvements on the dehydrogenation catalytic activities of Cu3X(111). Firstly, the specific inherent properties of the second alloyed metal X, including the d-band center, are crucial to the adsorption and activation of ethanol on surfaces. Sec-ondly, the electronic distribution on the surfaces resulting from the difference of electronega-tivity between the metals Cu and X is associated with the dehydrogenation reaction barrier. More electron density around the Cu atoms on these surfaces is more beneficial for dehydro-genation reactions, especially when H atoms were adsorbed stably on the Cu sites.