ScholarWorks@성균관대학교

초록

Platinum and nitrogen co-doped titanium dioxide (Pt/N-TiO2, with 1 wt% Pt and an N/Ti molar ratio of 1) has been synthesized. This Pt/N co-doping strategy creates Schottky junctions, reduces the bandgap energy (3.25 to 2.12 eV), and introduces a new energy level (N 2p). The modified catalyst exhibits dual functionality, serving as both a photocatalyst under light irradiation (λ = 365 nm, 32 W) and a light-free catalytic adsorbent against gaseous formaldehyde (FA). The Pt/N-TiO2 catalysts are immobilized on ceramic bead supports, placed in a tubular reactor system, and tested under controlled operating conditions, including FA concentrations (100–500 ppm), oxygen levels (0–21%), relative humidity (RH; 0–100%), and gas flow rates (100–500 mL min−1). The Pt/N-TiO2 achieves a photocatalytic oxidation efficiency of 94.2% (reaction rate of 9.24 μmol mg−1 h−1 and apparent quantum yield of 5.58%) against 200 ppm FA (100% RH). The catalyst's efficiency stems from a synergistic dual mechanism, as evidenced by molecular simulation using density functional theory. First, N doping enhances light absorption and extends the charge carrier lifetime, while the Pt as a co-catalyst promotes charge separation by acting as an electron sink. Second, the catalyst's ability to efficiently trap H2O and O2 molecules also contributes to the efficient mineralization of FA through the facile generation of reactive oxygen species. This dual functionality extends to dark conditions as a catalytic adsorbent, achieving a FA removal efficiency of 78.9% with a CO2 yield of 57%. In-situ diffuse reflectance infrared Fourier transform spectroscopy analysis confirms this mechanism by identifying the generation of Pt-OH hydroxylation and •O2− radicals from H2O vapor and O2, respectively. Overall, this research provides a practical guideline for constructing an advanced VOC abatement platform.

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