The promoting effect of visible light on the CO + NO reaction over the Pd/N–TiO2 catalyst†
Herein, a Pd nanoparticle catalyst supported on N-doped TiO2 (Pd/N–TiO2) was prepared by a chemical reduction method and evaluated for catalytic performance in the CO + NO reaction with and without visible light irradiation. It was found that the Pd/N–TiO2 catalyst exhibited excellent catalytic activity even at low temperatures, and upon introducing visible light, its catalytic performance was drastically enhanced. The results of in situ diffuse reflectance infrared Fourier transform spectra (in situ DRIFTS) indicated that visible light benefited the adsorption and activation of both NO (at N–TiO2 sites) and CO (at Pd sites) as well as formation of active intermediates (e.g. Ti4+–NO− and CO–Pd). On the basis of Raman spectroscopy, electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) results, it was proposed that Pd/N–TiO2 possessed numerous surface oxygen vacancies (SOVs-Ti3+), and visible light irradiation could promote the generation of SOVs and increase in the Pd surface electron density by photo-induced electron (from N2p to Ti3d orbit) transfer from N–TiO2 to Pd nanoparticles, resulting in enhanced adsorption and activation of CO and NO. Thus, a strengthened photo-assisted effect for the CO + NO reaction occurred on Pd/N–TiO2.
- This article is part of the themed collection: 2019 Catalysis Science & Technology HOT Articles