Reactions on the surface of catalysts are rather complex, and many possible reaction pathways and intermediates are involved. We here propose a method that is able to automatically generate a catalytic reaction network and identify the preferred reaction pathway with determined uncertainty. Taking syngas conversion to ethanol on Rh(111) as an example, a reaction network consisting of 95 elementary steps was generated. Using energies calculated with an ensemble of 2000 functionals, the occurrence frequency of different ethanol formation pathways was obtained through pruning of the reaction network with mean-field microkinetic modeling. We found that CHCO is the most important reaction intermediate for ethanol formation with the highest confidence, even at varied temperatures and pressures. The transition state of CH 3 CH 2 O hydrogenation, i.e. CH 3 CH 2 O−H, possesses the highest possibility to be rate-controlling. CO has the highest possibility to be the surface dominant species at all the temperatures and pressures considered. The method developed in the current work substantially reduces the complexity of identifying the mechanism of catalytic reactions and shows great potential in expediting future catalyst design.

A fundamental understanding of interactions between catalysts and gas molecules is essential for the development of efficient heterogeneous catalysts. In this study, ambient pressure X-ray photoelectron spectroscopy (APXPS) and density functional theory (DFT) simulation were employed to investigate the activation of CO2 on Cu surfaces, which acts as a key step in the catalytic reduction of CO2. APXPS results show that CO2 is adsorbed as CO2 δ− on the Cu(111) surface under a pressure of 0.01 mbar at 300 K. Adsorbed CO2 δ− gets partially transformed into carbonate with an increase of pressure to 1 mbar due to the disproportionation reaction between CO2 molecules. Subsequent annealing of the Cu(111) surface in a CO2 atmosphere leads to the dissociation of CO2 δ− and carbonate, and a transformation to a chemisorbed oxygen covered surface occurred at 400 K and elevated temperatures. However, on the Cu(110) surface, the CO2 δ− gradually dissociates to CO and chemisorbed oxygen in the presence of 1 mbar of CO2 at room temperature. The self-deactivation of CO2 adsorption due to the atomic oxygen generated by CO2 dissociation is observed on both Cu(111) and Cu(110) surfaces. Moreover, these experimental results indicate that the Cu(110) surface is more active than the Cu(111) surface in breaking C–O bonds, which is consistent with the results of DFT simulations. Our findings indicate that the activation of CO2 on Cu surfaces is strongly surface orientation- and pressure-dependent, which is an important step to clarify CO2 activation mechanisms on Cu-based catalysts.

Class F G protein-coupled receptors are characterized by a large extracellular domain (ECD) in addition to the common transmembrane domain (TMD) with seven α-helixes. For smoothened receptor (SMO), structural studies revealed dissected ECD and TMD, and their integrated assemblies. However, distinct assemblies were reported under different circumstances. Using an unbiased approach based on four series of cross-conjugated bitopic ligands, we explore the relationship between the active status and receptor assembly. Different activity dependency on the linker length for these bitopic ligands corroborates the various occurrences of SMO assembly. These results reveal a rigid “near” assembly for active SMO, which is in contrast to previous results. Conversely, inactive SMO adopts a free ECD, which would be remotely captured at “far” assembly by cholesterol. Altogether, we propose a mechanism of cholesterol flow-caused SMO activation involving an erection of ECD from far to near assembly.

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