Meng Yang, Wang Haiyan, Liang Jin-Xia, Zhu Chun, Li Jun
School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China.
Department of Chemistry and Guangdong Provincial Key Laboratory of Catalytic Chemistry, Southern University of Science and Technology, Shenzhen 518055, China.
Precis Chem. 2024 Jan 26;2(2):70-80. doi: 10.1021/prechem.3c00104. eCollection 2024 Feb 26.
Single-atom catalysts (SACs) provide an opportunity to elucidate the catalytic mechanism of complex reactions in heterogeneous catalysis. The low-temperature water-gas shift (WGS) reaction is an important industrial technology to obtain high purity hydrogen. Herein, we study the catalytic activity of Pt@TiCT (T = O, S) SACs, where one subsurface Ti atom with three T vacancies in the functionalized TiCT (T = O, S) MXene is substituted by one Pt atom, for the low-temperature WGS reaction, using density functional theory (DFT). The results show that Pt@TiCT provides an excellent platform for the WGS reaction by its bowl-shaped vacancy derived from the Pt single atom and three T defects surrounding it. Especially, Pt@TiCS SAC has higher catalytic performance for the WGS reaction, due to the weaker electronegativity of the S atom than the O atom, which significantly reduces the energy barrier of H* migration in the WGS reaction, which is often the rate-determining step. In the most favorable redox mechanism of the WGS reaction on Pt@TiCS, the rate-determining step is the dissociation of OH* into O* and H* with the energy barrier as low as 1.12 eV. These results demonstrate that Pt@TiCS is promising in the application of MXenes for low-temperature WGS reactions.
单原子催化剂（SACs）为阐明多相催化中复杂反应的催化机理提供了契机。低温水煤气变换（WGS）反应是获得高纯度氢气的一项重要工业技术。在此，我们使用密度泛函理论（DFT）研究了Pt@TiCT（T = O，S）单原子催化剂对低温WGS反应的催化活性，其中在功能化的TiCT（T = O，S）MXene中一个带有三个T空位的次表面Ti原子被一个Pt原子取代。结果表明，Pt@TiCT通过其由Pt单原子及其周围三个T缺陷衍生出的碗状空位为WGS反应提供了一个优异的平台。特别是，Pt@TiCS单原子催化剂对WGS反应具有更高的催化性能，这是由于S原子的电负性比O原子弱，这显著降低了WGS反应中H迁移的能垒，而H迁移通常是速率决定步骤。在Pt@TiCS上WGS反应最有利的氧化还原机理中，速率决定步骤是OH分解为O和H*，其能垒低至1.12 eV。这些结果表明，Pt@TiCS在MXenes用于低温WGS反应的应用中具有前景。
