Fig. 4: Kinetic information derived from phase-sensitive detection (PSD) analysis.
From: Uncovering the reaction mechanism behind CoO as active phase for CO2 hydrogenation
a Schematic representation of the H-assisted mechanism, dominant for CoO (suffix: -ox) catalysts, and the direct dissociation mechanism, dominant for metallic Co (suffix: -red) catalysts. b Phase-resolved amplitude spectra for Co/TiO2-ox and Co/TiO2-red. Desorption slopes (first 10 s after turning the CO2 gas off) of selected species for c Co/TiO2-ox and d Co/TiO2-red. Both samples showed carbonate, formate (*HCO22− indicated in red; 1609–1615 cm−1), and formyl species. Co/TiO2-ox additionally showed *CH2 species. For Co/TiO2-red, *CO (gray; 1980 cm−1) displayed faster kinetics (steeper slope) than the carbonate, formate, and formyl species. The direct dissociation mechanism was thus faster than the H-assisted mechanism.
