Enhanced interfacial contact of dopamine bridged melamine-graphene/TiO2 nano-capsules for efficient photocatalytic degradation of gaseous formaldehyde

• Published in: Applied catalysis. B, Environmental Vol. 232; pp. 182 - 193
• Main Authors: Zhu, Meiping, Muhammad, Yaseen, Hu, Peng, Wang, Bingfeng, Wu, Yang, Sun, Xiaodan, Tong, Zhangfa, Zhao, Zhenxia
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-09-2018
• Subjects: DFT simulation; Enhanced interfacial contact; Gaseous formaldehyde; Melamine-graphene/TiO2 nano-capsule; Photocatalytic degradation; Photocatalytic degradation; Gaseous formaldehyde; Melamine-graphene/TiO2 nano-capsule; DFT simulation; Enhanced interfacial contact
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.03.061

[Display omitted]
•N-doping and N-wrapping/bridging strategy was used to prepare TiO2 nano-capsules.•N-doping narrowed band gap and improved electrical conductivity of photocatalyst.•N-wrapping/bridging TiO2 displayed the highest charges separation efficiency.•Simulation showed N-doping accelerated adsorption sites transfer from Ti4+ to N.•H-TiO2@MG-D showed 4.1 times higher HCHO photodegradation efficiency than TiO2.
A novel synergistic strategy of N-doping and N-wrapping/bridging to synthesize photosensitive and conductive Graphene-TiO2 composite nano-capsules for gaseous HCHO degradation was proposed. High HCHO photodegradation activity of the composite was attributed to the enhanced interfacial contact of TiO2 with conductive melamine-doped graphene (MG) sheets by dopamine (DA) bridging. MG improved the electrical conductivity and photoinduced charges separation/transfer in the MG/TiO2 composite. Moreover, hydrogen treated DA wrapped/bridged MG/TiO2 composite (H-TiO2@MG-D) forming a 3D nano-capsule structure, which could concomitantly strengthen the interfacial contact between TiO2 and MG sheets and accelerates electron mobility. Characterization and DFT simulation results revealed that H-TiO2@MG-D nano-capsules exhibited the lowest band gap (2.49 eV) and highest charges separation efficiency. Simulation results further indicated that N-doping accelerated the transfer of adsorption sites from acidic Ti4+ (for HCHO) to basic N sites (for HCOOH and CO2) before and after HCHO degradation reaction. The enhanced interfacial contact of H-TiO2@MG-D resulted in its remarkably higher HCHO photocatalytic degradation efficiency (ŋ = 92%) and fast degradation rate (k = 15.04 × 10−3 min-1) than that of pristine TiO2 by a factor of 4.1 and 9.2, respectively. Therefore, the present study attributed to ease of synthesis and novel N-doping and N-wrapping strategy for the preparation of highly conductive MG-TiO2 composite can be deemed as an effective and promising pathway for HCHO photodegradation and other similar photocatalytic applications.