DFT Modeling of CO₂ Adsorption and HCOO^• Group Conversion in Anatase Au-TiO₂-Based Photocatalysis

Abstract

Due to the merits of carbon circulation and hydrocarbon production, solar-assisted photocatalysis has been regarded as an ideal option for securing a sustainable future of energy and environment. In the photocatalytic carbon cycle process, surface reactions including the adsorption of CO 2 and the conversion of CO 2 into CH 4 , CH 3 OH, etc. are crucial to be examined ascribed to their significant influence on the performance of the photocatalysis. Because the conversion reaction starts from the formation of HCOO • , the density functional theory (DFT) model was established in this study to investigate the micromechanism of CO 2 adsorption and the conversion of CO 2 to HCOO • group in the anatase Au-TiO 2 photocatalytic system. The CO 2 adsorption bonding in six configurations was simulated, on which basis the effects of the proportion of water molecules and the lattice temperature increase due to the local surface plasmon resonance (LSPR) on the photocatalytic CO 2 adsorption and conversion were specifically analyzed. The results show that the experimental conditions that water molecules are released before CO 2 are favorable for the formation of the adsorption configuration in which HCOO • tends to be produced without the need of reaction activation energy. This is reasonable since the intermediate C atoms do not participate in bonding under these conditions. Moreover, Au clusters have an insignificant influence on the adsorption behaviors of CO 2 including the adsorption sites and configurations on TiO 2 surfaces. As a result, the reaction rate is reduced due to the temperature increase caused by the LSPR effect. Nevertheless, the reaction maintains a very high rate. Interestingly, configurations that require activation energy are also possible to be resulted, which exerts a positive influence of temperature on the conversion rate of CO 2 . It is found that the rate of the reaction can be improved by approximately 1–10 times with a temperature rise of 50 K above the ambient.

Significant Acceleration of Photocatalytic CO2 Reduction to HCOOH at Gas-Liquid Interface

“…The XRD patterns (Fig. 1g, m) of the Au/TiO2 and Au/ZnO can be indexed to the anatase phase TiO2 and tetragonal ZnO, suggesting the high purity and crystallinity of metal oxides, in good agreement with early works 3,42,43 . The diffraction peaks are assigned to the cubic phase Au (JCPDS card no.…”

Polaron formation and transport in Bi2WO6 studied by DFT+U and hybrid PBE0 functional approaches

“…When the polaron moves to an adjacent site, the final state is formed. We used a linear interpolation formula 33 to calculate the polaron transfer pathway as follows:…”

“…When the polaron moves to an adjacent site, the final state is formed. We used a linear interpolation formula 33 to calculate the polaron transfer pathway as follows: q ( x ) = xq A + (1 − x ) q B where q A , q B , and q C denote vectors of the three-dimensional coordinates of all the atoms in the supercell. When x = 0, it is the initial state of polaron q B , and x = 1 is the final state q A ; x = 0.5 is taken as the transition state.…”

Electron and Hole Polaron Formation and Transport in Monoclinic WO3 Studied by Hybrid Functional Approach

“…We use the Marcus/Holstein theory to describe the polaron transport process, and several important parameters of the Marcus theory can be obtained through DFT calculations. − Polaron transfer mainly has three states: initial, transition, and final states. We can calculate the migration path of polarons through the linear interpolation formula as follows to obtain the energy curve of polaron transfer: q ( x ) = x q normalA + ( 1 − x ) q normalB where q A and q B are the three-dimensional coordinate vectors of atoms in supercells; 0 ≤ x ≤ 1, x = 0 is the initial state of the polaron hopping transport; x = 1 is the final state; and x = 0.5 is the transition state. The linear interpolation formula is widely used in the polaron transfer, such as in TiO 2 , , Fe 2 O 3 , Ta 3 N 5 , and so forth.…”