(111d) Determining the Adsorption Energetics of 2,3-Butanediol on RuO2(110) from First Principles

As climate change continues to pose a threat to the Earth’s carbon cycles and fossil fuel resources remain finite, more sustainable sources of hydrocarbons are being explored. 2,3-butanediol has been identified as potential source to produce butene, because of its sustainability as a biomass-derived sugar. As a first step toward elucidating the underlying mechanism, we compare the potential energy landscapes in the gas phase for the reported pathways using three different functionals (SCAN, optB86b-vdW and PBE), as seen for one pathway in Figure 1A. The SCAN functional was ultimately chosen since it correctly predicts the experimentally observed antiferromagnetic ground state for bulk RuO₂. In Figure 1B and 1C we compare the charge differentials for a physisorbed and a chemisorbed 2,3-butanediol adsorbate, which demonstrates how that the orientation of the molecule is essential for obtaining an optimized adsorption conformation. The ruthenium atoms act as Lewis acid sites by attracting the oxygen in the functional group, whereas oxygen atoms in the lattice can act as Lewis bases. We hypothesize that the dehydration reaction requires a stronger adsorption energy that necessitates surface defects such as oxygen vacancies. This systematic search of the most favorable adsorption site is further compared to the Northwest Potential Energy Search Engine, which enables the performance of global optimizations. As such, this work serves as first step toward the utilization of a global optimization algorithm for the rational design of Ru-based catalysts toward the formation of butene from sustainable resources.