(511d) A Molecular Level Understanding of Effect of Charge Condensation on Scaling Relationships of Water Gas Shift Reaction

Improving reaction kinetics in catalytic setups has focused on tuning the structural and compositional properties to effectively perform surface reaction and desorption steps at active sites. These energies depend on transition state (TS) viability, resulting in typical “scaling relationships” (SRs) for adsorbates. Sabatier plots arise from these reaction energetics correlations. While SRs are useful, there is a limit on their performance, in accordance with Sabatier principle. Condensing charge on active sites offers a method to extend these limits, achieved by depositing a catalytic layer over conductor/insulator/conductor layers and altering charge at the interface, thereby affecting electronic states and binding strength. Recent work at Center for Programmable Energy Catalysts (CPEC) has shown the method's applicability, with oscillating charge on alumina catalyst overcoming rate limitations for isopropanol dehydration. Whether the prediction regarding the relationship of intermediate and TS energies to SRs holds under charge condensation remains unclear for any catalytic reaction. Here, we employ computational means to study charge condensation's influence on SRs. Using the water gas shift (WGS) reaction as our model, chosen for its well-established SR and simplicity in understanding charge influence, we utilize five different metal catalysts (Fe, Cu, Ni, Ru, and Au) within a range of -0.18 to +0.18 h⁺ per site compared to experimentally observed ±0.1 h⁺ per site. Employing Density Functional Theory (DFT), we illustrate charge's influence on WGS reaction intermediates and TS. Our findings show positive charge significantly affects intermediate binding energies compared to negative charge. Additionally, our work suggests traditional SRs (O* vs OH*) do not scale linearly under a charged environment; instead, larger species like COOH* and HCO* exhibit scaling behavior. Furthermore, we discuss charge condensation's influence on TS scaling. Overall, our study sheds light on the intricate relationship between charge condensation and reaction kinetics, providing insights into catalytic mechanisms and design strategies.