As a key component of the oxide-zeolite composite catalyst for syngas conversion, the Cr-doped ZNO ternary system can be regarded as a model system for understanding oxide catalysts. However, due to the complexity of its structure, both experimental and theoretical methods have encountered significant challenges.
Based on this,Professor Hu Peijun (corresponding author) of Queen's University Belfast, UK, etcZNO(1010) surfaces with different CR and oxygen vacancy (OV) concentrations were explored using machine-Xi acceleration methods, including the giant canonical Monte Carlo method and genetic algorithm. Then, the effects of stable surfaces with different Cr and OV concentrations on CO activation were systematically investigated by DFT calculations.
The results show that Cr tends to preferentially occur on the surface of ZNO(1010) rather than its inner region, and that Cr-doped structures tend to form rectangular islands in the [0001] direction at high Cr and OV concentrations. On the surface of Cr-doped ZNO, the removal of oxygen attached to the Cr significantly enhanced the adsorption of CO. For the same component, the dicoordinated CR of the unreconstituted surface has a stronger CO adsorption energy than the tetracoordinated CR of the reconstituted surface.
In addition, the detailed calculation of CO reactivity revealed the inverse relationship between the reaction energy barrier (EA) of C-O bond dissociation and the CR and OV concentrations, and observed a strong relationship between the CO formation energy and CO activated EA. Further analysis showed that C-O bond dissociation was more favorable when the adjacent OVs were geometrically arranged in the [1210] direction and CR doped around the reaction site. These findings provide deeper insights into CO activation on Cr-doped ZNo surfaces and provide valuable guidance for the rational design of effective catalysts for syngas conversion.
unr**elling the impact of metal dopants and oxygen vacancies on syngas conversion over oxides: a machine learning-accelerated study of co activation on cr-doped zno surfaces. acs catal.,, doi: 10.1021/acscatal.3c03648.