Oxygen vacancy and nitrogen doping collaboratively boost performance and stability of TiO-supported Pd catalysts for CO photoreduction: a DFT study.

The regulation of interfacial charge transfer, optimization of active sites, and maintenance of stability are effective strategies for improving catalytic performance. The effect of the oxygen vacancy (V) and nitrogen doping on these parameters for CO photoreduction on Pd/TiO(101) was studied using density functional theory calculations. The results demonstrate that introduction of the V could trigger reversed electron transfer, making the V and Pd atoms the active center for CO reduction. However, the V is repaired by the dissociated O atom. The combined effect of the V and N is related to the position of N. Although the substitutional N (N) can delocalize electrons at the V, it cannot improve the activity and stability. The interstitial N (N) located below the V forms N-Ti bonds with two Ti atoms adjacent to the V. This can delocalize the electrons near the V, and the five-fold-coordinated titanium (Ti) replaces the V as the active center, thus enhancing the reactivity and protecting the V. Further research indicates that the co-modification of the V and N improves photoexcited electron transfer and distribution, which would in turn promote CO reduction. The results of this study propose that surface defect engineering holds great promise for boosting CO photoreduction by integrating functions of electron density modulation and catalysis.