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.

提出了一种新型的N掺杂和N包裹/桥接的协同策略，以合成光气和导电的石墨烯-TiO ₂复合纳米胶囊用于气态HCHO的降解。复合材料的高HCHO光降解活性归因于TiO ₂通过多巴胺（DA）桥接增强了与导电三聚氰胺掺杂的石墨烯（MG）片材的界面接触。MG改善了MG / TiO ₂复合材料的电导率和光诱导电荷的分离/转移。此外，氢处理的DA包裹/桥接的MG / TiO ₂复合材料（H-TiO ₂ @ MG-D）形成3D纳米胶囊结构，可以同时增强TiO ₂之间的界面接触。和MG形成薄片并加速电子迁移率。表征和DFT模拟结果表明，H-TiO ₂ @ MG-D纳米胶囊具有最低的带隙（2.49 eV）和最高的电荷分离效率。模拟结果进一步表明，在HCHO降解反应之前和之后，N掺杂加速了吸附位从酸性Ti ⁴⁺（对于HCHO）向碱性N位（对于HCOOH和CO ₂）的转移。H-TiO ₂ @ MG-D的界面接触增强，其HCHO光催化降解效率（ŋ  = 92％）和快速降解速率（k  = 15.04×10 ^-3  min ^-1）比原始TiO高。₂分别是4.1和9.2的因数。因此，本研究归因于易于合成以及制备高导电性MG-TiO ₂复合材料的新颖的N掺杂和N包裹策略，可以被认为是HCHO光降解和其他类似光催化应用的有效途径。