Promoting photoreduction selectivity via synergetic utilization between vacancy and nanofiber structure over flexible Zr/TiO2−x nanofiber films

Abstract

Photocatalytic conversion of CO₂ into value-added hydrocarbon fuels is a promising approach to alleviate the energy crisis caused by the overuse of fossil fuels. Here, a flexible Zr/TiO_2−x nanofiber photocatalyst with abundant oxygen-vacancies (OVs) has been fabricated and employed in the CO₂ photocatalytic reduction process. The selectivity for the photocatalytic reduction of CO₂ to CH₄ over H400-Zr/TiO_2−x nanofiber films could reach up to 87.6% which is rather high compared with currently reported photocatalytic systems. In-depth experiments demonstrate that the high product selectivity of CH₄ originated from the synergetic effect between vacancy and nanofiber structure in H400-Zr/TiO_2−x. Density functional theory (DFT) simulation reveals that the existence of a vacancy in H400-Zr/TiO_2−x facilitates a reduction in the surface free energy barrier from the intermediate CO* to CHO* during the production of CH₄, which is further confirmed by the observed obvious CHO* signal in in situ FTIR spectra. Additionally, the characteristic of one-dimensional long-range orientation and large surface area of nanofiber structure of H400-Zr/TiO_2−x is beneficial to providing more catalytic active sites which help to promote the CO₂ photoreduction property. This work paves the way for the efficient design of photocatalytic systems towards high conversion of CO₂ to CH₄.