(6f) Understanding the Solvent Effects of the Carbonyl Group Hydrogenation over a Pt(111) Catalyst in the Presence of Water

Carbonyl group hydrogenation over metal surfaces has served as a model system for investigating solvation phenomena in catalysis. Of particular interest is understanding the role of water as a co-catalyst, which has the potential to break the scaling relations of metal catalysis and modulate the kinetics of heterogeneous catalysts by going three-dimensional. Water's ability to accelerate or inhibit the hydrogenation rate strongly depends on the transition metal surfaces, such as Pt, Pd, and Ru. Demir et al. revealed that water vapor decreases the hydrogenation rate of carbonyl groups in acetone over Pt and increases the rate over Ru. Conversely, Zhao et al. reported an acceleration in the hydrogenation of carbonyl groups in furfural over Pd catalysts in liquid water, attributed to proton-coupled electron transfer steps. Previous findings from our group highlighted an enhancement in the hydrogenation rate of the C=O double bond within carbonyl groups in the presence of water on Ru(0001). Yet, the influence of water on Pt catalysts in these reactions remains underexplored. Therefore, this study focuses on the hydrogenation of 2-butanone on Pt(111) and contrasts our findings with our prior Ru(0001) study. We studied the 2-butanone hydrogenation over Pt(111) with our explicit solvation method for metal surfaces (eSMS). Our computations show kinetically favorable reactions in the presence of adsorbed water for hydrogenating the carbonyl group oxygen. At the same time, the C-atom hydrogenation is the rate-determining step over Pt(111). Interestingly, water vapor does not alter Pt reactions as a co-catalyst, aligning with recent findings of water's non-participation in Pt catalyst carbonyl hydrogenation. Ultimately, water's ability to accelerate or inhibit a reaction on different metal surfaces strongly depends on the rate controlling step on these surfaces. The carbonyl group hydrogenation fundamentally differs between Pt(111) and Ru(0001), with C-atom hydrogenation and O-atom hydrogenation being rate controlling, respectively.