Abstract
Herein, we have investigated the CO2 reduction paths on the (101) anatase TiO2 surface using an approach based on the density functional tight binding (DFTB) theory. We analyzed the reaction paths for the conversion of carbon dioxide to methane by performing a large number of calculations with intermediates placed in various orientations and locations at the surface. Our results show that the least stable intermediate is CO2H and therefore a key bottleneck is the reduction of CO2 to formic acid. Hydrogen adsorption is also weak and would also be a limiting factor, unless very high pressures of hydrogen are used. The results from our DFTB approach are in good agreement with the hybrid functional based density functional theory calculations presented in the literature.
Highlights
The phenomenon of “global warming” caused by emission of CO2 to the earth atmosphere puts a demand to achieve a fossilfree economy and make use of sustainable energy sources such as sun, wind, geothermal, and hydrothermal.[1]
Accurate and widely transferable, density functional theory (DFT) is typically too computationally demanding to widely screen a large number of adsorption geometries of structures such as nanoparticles or complex surfaces with multiple defects, surface kinks, impurities, and so forth. Alternative, approximate methods such as density functional tight binding (DFTB) are capable of targeting such systems, but their accuracy and limitations need to be established for the current application
The anatase TiO2 nanoparticles, which are typically implemented in energy and catalytic applications, are predominantly exposing the most thermodynamically stable (101) facets along with a small fraction of the (001)[33,34] facet
Summary
The phenomenon of “global warming” caused by emission of CO2 to the earth atmosphere puts a demand to achieve a fossilfree economy and make use of sustainable energy sources such as sun, wind, geothermal, and hydrothermal.[1]. In a recent publication, such mechanisms, when taking place at the pristine anatase (101), were explored by means of density functional theory (DFT).[16] accurate and widely transferable, DFT is typically too computationally demanding to widely screen a large number of adsorption geometries of structures such as nanoparticles or complex surfaces with multiple defects, surface kinks, impurities, and so forth. Alternative, approximate methods such as density functional tight binding (DFTB) are capable of targeting such systems, but their accuracy and limitations need to be established for the current application. We have analyzed the most critical steps in the reaction in an anatase nanoparticle model, which cannot be pursued by a similar DFT approach
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