Enhancing the sensitivity of Co-doped LaFeO3 thick-film sensors for low-concentration CO2 detection: Investigating the synergistic effect of complex defects and adsorbed oxygen

This study employs the HSE06 hybrid functional within density functional theory (DFT) to investigate the adsorption behavior of CO 2 on Co-doped LaFeO 3 (001) surfaces, focusing on the influence of single and complex defects, as well as the synergistic interactions between complex defects and adsorbed oxygen. Our analyses of adsorption energy , Gibbs free energy , charge density, and electronic structure demonstrate that La-defective surfaces exhibit superior CO 2 adsorption efficiency compared to Fe-defective surfaces. Notably, the La+O complex defect surface demonstrates the most significant adsorption enhancement after pre-adsorption of oxygen, with a bandgap reduction to 0.22 eV and an electron transfer of 1.13 e. Experimental verification using hydrothermally synthesized sensors with different defect states confirms the theoretical findings. These sensors demonstrate enhanced sensitivity to 500 ppm CO 2 , with the highest response (1.50) achieved by the La+O defect sensor following oxygen enrichment . This work provides a theoretical and experimental foundation for optimizing CO 2 gas sensitivity in perovskite-type metal oxides , offering guidance for the development of low-cost, high-performance CO 2 gas sensors. • La defects enhances the sensor’s sensitivity to 500 ppm CO 2 in comparison to Fe defects. • La defects and vacuum/oxygen-rich treatments effectively enhance sensor gas sensitivity. • Response of GL3 sensor to 500 ppm CO 2 gas at a working temperature of 120℃ is 1.50.