# Tailoring Electronic Structures via Ce/C Co-Doping and Oxygen Vacancy in TiO2 Aerogels for Enhanced Solar Fuel Production

## TL;DR

Researchers improved TiO2 aerogels by adding cerium and carbon, creating oxygen vacancies that boost solar fuel production from CO2 under sunlight.

## Contribution

A novel Ce/C co-doping strategy combined with oxygen vacancies enhances TiO2 aerogels for efficient CO2 reduction without co-catalysts.

## Key findings

- Ce/C co-doped TiO2 aerogels achieved CH4 and CO production rates 82.0 and 5.7 times higher than pristine TiO2 under simulated sunlight.
- Oxygen vacancies formed by C-doping increase light absorption and extend charge carrier lifetimes, improving photocatalytic performance.
- DFT calculations and experiments confirm that defect states from oxygen vacancies enable efficient CO2 reduction.

## Abstract

A targeted modification approach involving the synthesis of Ce/C co-doped TiO2 aerogels (CeCTi) via a sol–gel method combined with supercritical CO2 drying and subsequent heat treatment is employed to enhance the photocatalytic CO2 reduction performance of cost-effective and stable TiO2 aerogels. The results demonstrate that the CeCTi exhibits a pearl-like porous network structure, an optical band gap of 2.90 eV, and a maximum specific surface area of 188.81 m2/g. The black aerogel sample shows an enhanced light absorption capability resulting from the Ce/C co-doping, which is attributed to the formation of oxygen vacancies. Under simulated sunlight irradiation, the production rates of CH4 and CO reach 27.06 and 97.11 μmol g−1 h−1 without any co-catalysts or sacrificial agents, respectively, which are 82.0 and 5.7 times higher than those of the pristine TiO2 aerogel. DFT reveals that C-doping facilitates the formation of oxygen vacancies, which introduces defect states within the calculational band gap of TiO2. The proposed photocatalytic mechanism involves the light-induced excitation of electrons from the valence band to the conduction band, their trapping by oxygen vacancies to prolong the charge carrier lifetime, and their subsequent transfer to adsorbed CO2 molecules, thereby enabling efficient CO2 reduction, which is experimentally supported by photoluminescence measurements.