单原子Pd修饰调控B,N共掺杂多孔碳球表界面功能层的构筑及其选择性催化甲醛氧化机理研究

Room-temperature catalytic oxidation is an environment-friendly technology and regarded as an ideal choice for the removal of formaldehyde (HCHO). However, the poor selective adsorption ability and inactivation of the active sites on traditional catalysts are important factors affecting the removal efficiency of HCHO. In addition, those factors are also the key scientific issues to be solved urgently in this field. Several studies have shown that the electron-deficient nature of B atoms have unoccupied valence orbitals, which can form the chemical bonds with unpaired valence electrons. The existence of single-atom Pd active site in the form of "isolated" is prone to adsorb O2 for production of the reactive oxygen species (O*). This single site adsorption behavior called Griffiths’ adsorption model. Therefore, this project proposal seeks to develop a highly efficient catalyst, which is made of B, N co-doped porous carbon sphere with single-atom Pd-modified surface interface functional layer (Pd1/BNCB). Specifically, the structurally stable of single-atom Pd is beneficial for production of O*, and has strong antioxidant capacity to prevent the oxidation of single-atom Pd from self-produced highly active O*. Furthermore, the selective chemical adsorption is obtained through the interaction between the valence orbitals of adjacent B atoms and valence electrons of carbonyl oxygen atoms in the carbonyl group of HCHO, which enables it to oxidize and degrade the adsorbed HCHO pollutant efficiently, thus providing a theoretical basis for enhancing the selective and stable catalytic performance of HCHO oxidation.

室温催化氧化作为一种环境友好的氧化技术，被认为是去除室内甲醛(HCHO)污染物的理想选择。传统吸附位点选择性吸附HCHO能力差及活性位点易失活严重影响了HCHO的去除效率，也是目前该领域亟待解决的关键科学问题。研究表明，具有缺电子特性的B原子有充分利用的价轨道，能与未成键的价电子形成化学键，而以“孤立”形式存在的单原子Pd活性位点易与O2发生Griffiths吸附产生活性氧(O*)。基于此，本项目利用单原子Pd修饰调控B,N共掺杂多孔碳球表界面功能层(Pd1/BNCB)。一方面，Pd与N的强配位作用形成的单原子Pd，结构稳定，难以被自身活化O2产生的O*氧化，抗氧化能力强，不易失活；另一方面，邻近的B原子中的空轨道与HCHO中羰基氧原子中未成键的孤对电子易发生选择性化学吸附，使O*能够及时氧化降解HCHO，为增强Pd1/BNCB选择性稳定催化HCHO氧化性能提供理论依据。

甲醛是一种典型的室内空气污染物，具有极强的致癌作用，严重威胁着人类健康。在众多净化甲醛技术中，室温催化氧化作为一种极具前景的矿化甲醛方法，被广泛认为是净化室内甲醛的最佳选择。然而，传统室温催化甲醛氧化催化剂表面活性位点密度低严重影响其甲醛的去除效率，也是目前该领域亟待解决的关键科学问题。在本项目研究中，申请者成功地利用B/N路易斯对与甲醛分子中羰基氧和羰基碳原子的“耦合”作用，进而实现精准吸附空气中的甲醛污染物；另外，具有富电子特性的Pd位点能够有效地吸附活化氧气分子，将其劈裂成活性氧物种，从而实现高效稳定催化甲醛氧化的目标。相关重要的研究成果发表在Applied Catalysis B: Environmental 2022, 318: 121780 和Applied Catalysis B: Environmental 2020, 272: 118992等期刊上。