Accuracy of Density Functional Theory for Predicting Kinetics of Methanol Synthesis from CO and CO2 Hydrogenation on Copper

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Density functional theory (DFT) is widely used for investigating heterogeneous catalysis; however, the predictive power of DFT is determined by the approximation used in the exchange–correlation (XC) functionals. In this work, we systematically investigate how the kinetics of methanol synthesis predicted by DFT depends on the choice of XC functionals. Microkinetic modeling is performed based on the Gibbs energies calculated with XC functionals that represent three levels of accuracy: Perdew–Burke–Ernzerhof (PBE) functional, Heyd–Scuseria–Ernzerhof (HSE) hybrid functional, and the random phase approximation (RPA) functional. We show that the predicted kinetics strongly depends on the choice of XC functionals. Methanol’s turnover frequencies predicted by PBE and HSE are about 30 times faster than the predictions from RPA. PBE predicts that the overall barrier of CO hydrogenation is 0.56 eV lower than that of CO2 hydrogenation, therefore suggesting CO as the carbon source for methanol synthesis on copper. Th...