Thermodynamic and Kinetic Study of Carbon Dioxide Hydrogenation on the Metal-Terminated Tantalum-Carbide (111) Surface: A DFT Calculation

Abstract

The need to reduce our reliance on fossil fuels and lessen the environmentally harmful effects of CO2 have encouraged investigations into CO2 hydrogenation to produce useful products. Transition metal carbides exhibit a high propensity towards CO2 activation, which makes them promising candidates as suitable catalysts for CO2 hydrogenation. Here, we have employed calculations based on the density-functional theory to investigate the reaction network for CO2 hydrogenation to product molecules on the tantalum-terminated TaC (111) surface, including two routes from either HCOOH* or HOCOH* intermediates. Detailed calculations of the reaction energies and energy barriers along multiple potential catalytic pathways, along with the exploration of all intermediates, have shown that CH4 is the predominant product yielded through a mechanism involving HCOOH, with a total exothermic reaction energy of −4.24 eV, and energy barriers between intermediates ranging from 0.126 eV to 2.224 eV. Other favorable products are CO and CH3OH, which are also produced via the HCOOH pathway, with total overall reaction energies of −2.55 and −2.10 eV, respectively. Our calculated thermodynamic and kinetic mechanisms that have identified these three predominant products of the CO2 hydrogenation catalyzed by the TaC (111) surface explain our experimental findings, in which methane, carbon monoxide, and methanol have been observed as the major reaction products.

Carbon dioxide hydrogenation over the carbon-terminated niobium carbide (111) surface: a density functional theory study

“…DFT-D3 is the primary methodology used for these types of calculations in the field of heterogeneous catalysis, with similar set-ups having been reported widely in the literature, thus enabling direct comparison of our results with previous work. 32,42,43 Solvent effects were not included in our calculations. Although these may affect the adsorption characteristics of the various molecules at the surface, they would not alter significantly the relative energies of the adsorbed intermediates and thus would not affect the trends identified in this work.…”

Determining the hydrocarbon chain growth pathway in Fischer–Tropsch synthesis through DFT calculations: impact of cobalt cluster size

“…38,39 The structures were optimized using the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) functional. 40 Max force, max displacement, and energy cutoff were considered equal to 0.05 eV Å À1 , 0.002 Å, and 400 eV, respectively. 28…”

Machine Learning-Driven Discovery of Key Descriptors for CO2Activation over Two-Dimensional Transition Metal Carbides and Nitrides

“…Note in passing by that for CO 2 activation, we refer here to a strong interaction between the CO 2 molecule and the MXene surfaces, leading to significant changes in the adsorbed CO 2 geometry, including a bent geometry with elongated C−O bonds and a molecular negative charge, resulting from a charge transfer from the MXene surface to CO 2 . This CO 2 activation must not be misled with another widely used meaning, implying the CO 2 conversion into other chemicals, e.g., CO, formic acid, methanol, and so on, although both definitions are connected, since the bent CO 2 geometry is quite often the key, decisive state in CO 2 conversion, as found in organometallics, 33 TM carbides, 34 MXenes, 35 metals, 36 alloys, 37 and oxide-based catalysts. 38,39 Thus, the fundamental goal of the present study is to develop and understand ML models for activated CO 2 adsorption on MXenes, which can be quantitatively implemented and leveraged for the predictive analysis in drawing useful information into the process of CO 2 posterior conversion.…”

“…This CO 2 activation must not be misled with another widely used meaning, implying the CO 2 conversion into other chemicals, e.g. , CO, formic acid, methanol, and so on, although both definitions are connected, since the bent CO 2 geometry is quite often the key, decisive state in CO 2 conversion, as found in organometallics, 33 TM carbides, 34 MXenes, 35 metals, 36 alloys, 37 and oxide-based catalysts. 38 , 39 …”