Recognizing the formation of single-atom vanadium by enthalpy and its advantage in selective catalytic reduction of nitrogen oxide

Abstract

Developing a more effective catalyst for the environmental pollutant is always the pursuit of worldwide researchers. In previous reports, most works were focused on prepared catalysts, and more efforts should explore process from a precursor to the formed catalyst. In this work, V supported TiO2 catalysts were synthesized with different V loadings, and compared in selective catalytic reduction of nitrogen oxide. For the first time, differential scanning calorimetry was used to analyze the forming enthalpy for these catalysts. As a result, turnover frequency (TOF) was decreased from 0.05 to 0.001 s−1 when the loading was increased from 0.05 to 15 mol%. At the same time, the forming enthalpy was decreased from 16.53 to 1.80 KJ·mol−1. Spherical Aberration Corrected Transmission Electron Microscope recognized both single-atom and cluster V even at the lowest loading. What’s more, density functional theory revealed that single-atom V had a lower dehydrogenation energy (1.088–1.152 eV) than cluster V during the catalysis (1.834–1.850 eV). According to these evidences, single-atom V had bigger formation enthalpy, lower dehydrogenation energy, and larger TOF than cluster V. These results help to optimize the preparation process for an effective catalyst, which is in favor of hazardous-pollutant treatment.