How Rh surface breaks CO2 molecules under ambient pressure

Abstract

Utilization of carbon dioxide (CO2) molecules leads to increased interest in the sustainable synthesis of methane (CH4) or methanol (CH3OH). The representative reaction intermediate consisting of a carbonyl or formate group determines yields of the fuel source during catalytic reactions. However, their selective initial surface reaction processes have been assumed without a fundamental understanding at the molecular level. Here, we report direct observations of spontaneous CO2 dissociation over the model rhodium (Rh) catalyst at 0.1 mbar CO2. The linear geometry of CO2 gas molecules turns into a chemically active bent-structure at the interface, which allows non-uniform charge transfers between chemisorbed CO2 and surface Rh atoms. By combining scanning tunneling microscopy, X-ray photoelectron spectroscopy at near-ambient pressure, and computational calculations, we reveal strong evidence for chemical bond cleavage of O‒CO* with ordered intermediates structure formation of (2 × 2)-CO on an atomically flat Rh(111) surface at room temperature.

RETRACTED: Current Developments in Catalytic Methanation of Carbon Dioxide—A Review

“…Luo et al (2020) described the remarkable activity and stability of PdFe intermetallic nanocrystals for CO 2 methanation. At 180 °C, CO 2 :H 2 ratio of 1:4 and 1 bar, the maximum yield of facecentered-tetragonal (fct) PdFe catalyst was 5.3 mmol g −1 h −1 , an increase of 6.6, 1.6, 3.3, and 5.3-fold compared to face- (Jacquemin et al, 2010;Beuls et al, 2012;Kim et al, 2020) Frontiers in Energy Research | www.frontiersin.org January 2022 | Volume 9 | Article 795423 centered-cubic (fcc) PdFe nanocrystals, Ru/C, Ni/C, and Pd/C catalysts. The fct-PdFe nanocrystals also maintained 98% activity after 20 successive runs.…”

Controlling CO2 hydrogenation selectivity by Rh-based catalysts with different crystalline phases of TiO2

“…1 CO 2 capture, storage, and utilization (CCSU) is an effective way to address the change in climate conditions caused by the greenhouse effect. Many high-value chemicals can be obtained by carbon dioxide hydrogenation, such as CO, 2 methane, 3 methanol, 4 high-quality gasoline, 5 and aromatics. 6 Among these, CO 2 methanation and CO 2 hydrogenation to CO, CH 4 , or methanol are considered to be the ideal routes for the utilization of CO 2 , and these simple reaction processes make it easy to explore the initial steps of CO 2 hydrogenation.…”

Operando Observation of Oxygenated Intermediates during CO Hydrogenation on Rh Single Crystals

“…XPS studies of Rh and other syngas catalysts have consequently been limited to pressures around or below 0.2 mbar. 15 − 17 With recent advances in XPS instrumentation and the virtual pressure cell concept, we now have the experimental tools to examine reaction conditions at pressures in the hundreds of mbar regime. 18 …”

“… 10 , 19 , 20 This comparison is important because the feasibility of CO and CO 2 bond breaking on Rh(111) has been debated. 21 − 25 …”

“…The weak binding of CO 2 to Rh results in a short residence time on the surface and, in turn, low probability for CO 2 dissociation. 17 The higher coverage of the (211) surface compared to the (111) surface is expected because the dissociation rates of CO 2 have been estimated to be faster because of lower barriers on the (211) surface. 34 , 35 …”