<p>A comprehensive mechanistic insight into the photocatalytic reduction of CO<sub>2</sub> by H<sub>2</sub>O is indispensable for the development of highly efficient and robust photocatalysts for artificial photosynthesis. This work presents first-principles mechanistic insights into the adsorption and activation of CO<sub>2</sub> in the absence and presence of H<sub>2</sub>O on the (001), (010), and (110) surfaces of tantalum nitride (Ta<sub>3</sub>N<sub>5</sub>), a photocatalysts of significant technological interest. The stability of the different Ta<sub>3</sub>N<sub> </sub>surfaces is shown to dictate the strength of adsorption and the extent of activation of CO<sub>2</sub> and H<sub>2</sub>O species, which bind strongest to the least stable Ta<sub>3</sub>N<sub>5</sub>(001) surface and weakest to the most stable Ta<sub>3</sub>N<sub>5</sub>(110) surface. The adsorption of the CO<sub>2</sub> on the Ta<sub>3</sub>N<sub>5</sub>(001), (010), and (110) surfaces is demonstrated to be characterized by charge transfer from surface species to the CO<sub>2</sub> molecule, resulting in its activation (i.e., forming negatively charged bent CO<sub>2</sub><sup>−δ</sup> species, with elongated C–O bonds confirmed via vibrational frequency analyses). Compared to direct CO<sub>2 </sub>dissociation, H<sub>2</sub>O dissociates spontaneously on the Ta<sub>3</sub>N<sub>5</sub> surfaces, providing the necessary hydrogen source for CO<sub>2</sub> reduction reactions. The coadsorption reactions of CO<sub>2</sub> and H<sub>2</sub>O are demonstrated to exhibit the strongest attractive interactions on the (010) surface, giving rise to proton transfer to the CO<sub>2</sub> molecule, which causes its spontaneous dissociation to form CO and 2OH<sup>−</sup> species. These results demonstrate that Ta<sub>3</sub>N<sub>5</sub>, a narrow bandgap photocatalyst able to absorb visible light, can efficiently activate the CO<sub>2</sub> molecule and photocatalytically reduce it with water to produce value-added fuels.<br></p><p>The data underpinning the research are available in the .xlsx format (can be viewed either by MS Office or Libre Office) comprising 6 datasheets, which gives information about the bulk structure of Ta3N5; structures of the (001), (010) & (110) surface; CO2 and H2O adsorption structures adsorption on (001), (010), and (110) surfaces of tantalum nitride (Ta3N5). Data for the optimized structures are available in CONTCAR format of the VASP simulation program. The CONTCAR files consist of lattice parameters and atomic positions and can be viewed either by MS Office or WordPad and displayed using VESTA software.</p><p>Research results based upon these data are published at https://doi.org/10.3390/catal10101217<br></p><p><br></p>
Funding
Computer-aided design of zinc phosphide heterojunctions for efficient solar energy conversion
Engineering and Physical Sciences Research Council