Understanding the electrochemical reaction mechanisms of precious metals Au and Ru as cathode catalysts in Li–CO₂ batteries

Abstract

The electrochemical reaction mechanisms of Au and Ru as cathode catalysts in Li-CO2 batteries are firstly studied by First-principles density functional theory (DFT) calculations. During the discharging process, the free...

Mechanical Understanding of Li–CO2 Batteries: The Critical Role of Forming Intermediate *Li2O

“…Unveiling mechanisms are essential for advancing catalyst design. − Recently, many efforts have been made to reveal the mechanism of Li–CO 2 batteries based on experimental characterizations and theoretical calculations, but the reaction mechanism remains controversial. − For example, the reaction of *CO + CO 2 → *CO 3 + C has been suggested as a critical step for the generations of Li 2 CO 3 and C. However, such a step is actually infeasible because of its relatively high energy barriers. , Besides the conventional product of Li 2 CO 3 , many other Li-containing discharge products were also detected experimentally. For instance, Li 2 C 2 O 4 has been identified as the final discharge product for Mo 2 C-based catalysts. , In contrast, Li 2 C 2 O 4 was observed as a reaction intermediate (rather than the final product) in the initial discharge stage over Au and porous carbon catalysts.…”

Advancing next-generation nonaqueous Mg–CO2batteries: insights into reaction mechanisms and catalyst design

“…5). 44,47 We also studied the possibility of MgCO 3 formation along with C and CO 2 from CO splitting and found that the calculated Gibbs free energy of CO disproportionation is 1.72 eV. Overall, the free energy changes for the rate-controlling step of the first splitting reactions in (1) and (2) are −1.54 eV and 0.19, respectively.…”

“…The interatomic distances between C and the surface atoms are significantly shorter (1.450 Å) than that of O (2.309 Å) in CO 2 , and the adsorption of CO 2 exhibits a proclivity to form a “V” configuration, which is consistent with previous experimental and theoretical studies. 45–48 Upon closer inspection, we found that the adsorbed CO 2 onto the catalytic surface resulted in a twisted angle of 130° between the two CO bonds. Additionally, the CO bond distance was significantly elongated, from 1.176 Å in the gas phase to 1.286 Å on α-Mo 2 C (001).…”

“…The predicted direct CO 2 activation on the Mo 2 C substrate is anticipated to generate the C 2 O 4 intermediate from the chemical dimerization of two CO 2 molecules (C–C coupling) similar to previous studies on Li–CO 2 batteries. 47 Furthermore, the nucleation of MgC 2 O 4 (paths III and IV) involving Mg and electron transfer intermediate steps is also downhill with a negative free energy change of −3.14 eV and −3.12 eV (see Fig. 4a and S9†).…”

“…These observations suggest that the absorbed CO 2 molecule is highly reactive, which is consistent with previous studies. 44,47 What's more, the projected density of states (PDOS) analysis (Fig. S3 †) highlights the dominant contribution of Mo-4d states to the catalyst's metallic behavior.…”