The mechanism of room temperature catalytic C–H dissociation and oxygenation of formaldehyde over nano-zirconia phase-junction

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2020-01, Vol.380, p.122498, Article 122498
• Main Authors: Zhang, Yufei, Huang, Yu, Lee, Shun Cheng, Cao, Jun-ji
• Format: Article
• Language: English
• Subjects: Activation barrier; Catalytic oxidation of HCHO; C–H dissociation; Interfacial electrons transfer; ZrO2 phase-junctions
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.122498

•Nano-zirconia tetragonal-monoclinic phase junction was synthesized.•Enhanced C–H dissociation of HCHO at phase junction interface was found.•Interfacial molecular O2 formed OOH groups through the hydrogenation reaction.•D-H and Mvk pathways of room temperature catalyzing HCHO were proposed.•The highest conversion efficiency of HCHO into CO2 was around 81% at 25 °C. The room temperature catalytic efficiency of formaldehyde (HCHO) is determined by interfacial electrons transfer properties, gas adsorption configuration and reactivity of catalysts. The phase-junctions with lattice planes of high matching degree and abundant active sites may do better in the above three aspects than traditional catalysts and their heterojunctions. In this work, tetragonal-monoclinic nano-zirconia (ZrO2) phase-junctions (TMZ) were synthesized for the first time. The highest conversion efficiency of HCHO into CO2 was around 81% at 25 °C exceeded the value for pure ZrO2. Density functional theory calculations and in-situ diffuse reflectance infrared Fourier transform spectroscopy measurements revealed that the adsorption enhancement of rich zirconium sites and single electron activation at TMZ interface caused C–H dissociation of HCHO and hydrogenation of O2 (D–H), significantly lowering the activation barrier of catalytic oxidation of HCHO. Our findings can facilitate further design of more active catalyst for room temperature removal of HCHO.