Nature of Catalytic Behavior of Cobalt Oxides for CO₂ Hydrogenation

Abstract

Cobalt oxide (CoO x ) catalysts are widely applied in CO2 hydrogenation but suffer from structural evolution during the reaction. This paper describes the complicated structure–performance relationship under reaction conditions. An iterative approach was employed to simulate the reduction process with the help of neural network potential-accelerated molecular dynamics. Based on the reduced models of catalysts, a combined theoretical and experimental study has discovered that CoO(111) provides active sites to break C–O bonds for CH4 production. The analysis of the reaction mechanism indicated that the C–O bond scission of *CH2O species plays a key role in producing CH4. The nature of dissociating C–O bonds is attributed to the stabilization of *O atoms after C–O bond cleavage and the weakening of C–O bond strength by surface-transferred electrons. This work may offer a paradigm to explore the origin of performance over metal oxides in heterogeneous catalysis.

Tailoring the active phase of CoO-based thin-film catalysts in order to tune selectivity in CO2 hydrogenation

“…Consequently, it can be concluded that CoO plays an important role in H 2 adsorption and dissociation, thereby promoting CO 2 methanation. It is noteworthy that, Li et al 30 by calculating the energy profile of H 2 dissociation on different planes of CoO and Co 0 showed that H 2 dissociation on CoO (111) sites is comparable to Co 0 (111), indicating easy dissociation on CoO (111) similar to Co 0 , both characterized by low barriers. Considering the fact that, as mentioned earlier, the major crystallographic site of cubic CoO in the CoO-based thin-film catalyst is CoO (111), the higher CH 4 production on catalysts with higher CoO sites can be attributed to the feasible activation of H 2 on these CoO sites.…”

Cobalt Oxide on Boron-Doped Graphitic Carbon Nitride as Bifunctional Photocatalysts for CO2 Reduction and Hydrogen Evolution

“…In addition, introducing other elements into g-C 3 N 4 could build intermediary electronic states and/or elemental defects, boosting the separation of photogenerated charges and electron mobility, especially forming dual-active sites at interfaces . In particular, Co-based oxides (CoOx) have been demonstrated as promising materials for CO 2 hydrogenation due to their electronic and optical properties, which also help in intermediates’ stabilization after C–O cleavage by transferred surface electrons. − For instance, Co 3 O 4 has been regarded as a favorable semiconductor material with remarkable CO 2 photoreduction to CH 4 and CO under simulated solar irradiation …”

Origin of Autocatalytic Behavior of Water over CuZn Alloy in CO2 Hydrogenation

“…In today’s era of global environmental degradation and energy crisis, CO 2 hydrogenation, as a mature technology for the utilization of CO 2 (greenhouse gas), enables the production of high-value-added products while consuming CO 2 , which is of considerable attraction. − In the CO 2 hydrogenation reaction, water (H 2 O) is inevitably produced as a byproduct, when CO 2 and H 2 are converted to the target product. The presence of excess water in the system has been reported to lead to the deactivation of catalysts. − Excess water molecules may compete with key reaction intermediates for the adsorption of active sites, resulting in the block or oxidation of active sites. , The accumulation of water may also accelerate the crystallization process and cause the sintering of catalysts .…”