Dry Reforming of Methane on Ni/LaZrO2 Catalyst under External Electric Fields: A Combined First-Principles and Microkinetic Modeling Study

Dry reforming of methane (DRM) reaction has great potential in reducing the greenhouse effect and solving energy problems. Herein, the DRM reaction mechanism and activity on Ni₁₆/LaZrO₂ catalyst under electric fields were comprehensively investigated by combining density functional theory calculations with microkinetic modeling. The results showed that La doping increases the interaction between Ni and ZrO₂ by Ni cluster transfer of more electrons. The adsorption strength of species followed the order Ni₁₆/ZrO₂ > Ni₁₆/LaZrO₂, which is consistent with the results for the d-band center but opposite to the metal-support interaction. The best DRM reaction path on Ni₁₆/LaZrO₂ was the CH₂-O pathway, which is different from the CH-O pathway on Ni(111) and Ni₁₆/ZrO₂. Both positive and negative electric fields of strong and weak metal-support interactions reduced the energy barrier of DRM reaction. Importantly, our results showed that the more dispersed and smaller Ni₁₂/LaZrO₂ model by considering the dispersing effect induced by La doping, which displayed very different results from that of Ni₁₆/LaZrO₂: reduced the energy barrier for methane decomposition, thereby promoting DRM reaction activity. Microkinetic results showed that the carbon deposition behavior of DRM becomes weaker on Ni₁₆/LaZrO₂ due to the suppression of methane decomposition in the presence of La doping compared to Ni₁₆/ZrO₂, but the opposite result is obtained on Ni₁₂/LaZrO₂. The order of DRM reactivity was Ni₁₆/LaZrO₂ < Ni₁₆/ZrO₂ < Ni₁₂/LaZrO₂, which is consistent with the experiment observations. The conversion of methane and CO₂ was higher in positive electric fields than in negative electric fields at low temperatures, but the results were opposite at high temperature. Negative electric fields can improve the carbon deposition resistance of Ni-based catalysts compared to positive electric fields. The degree of rate control analysis showed that CH_x* oxidation also plays an important role in the DRM reaction. We envision that this study could provide a deeper understanding for guiding the widespread application of electric field catalysis.