Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
Faculty of Science, Department of Chemistry, King Abdulaziz University , Jeddah 21577, Saudi Arabia.
ACS Appl Mater Interfaces. 2016 Aug 10;8(31):19853-9. doi: 10.1021/acsami.6b05427. Epub 2016 Jul 28.
Examinations of enzymatic catalysts suggest one key to efficient catalytic activity is discrete size metallo clusters. Mimicking enzymatic cluster systems is synthetically challenging because conventional solution methods are prone to aggregation or require capping of the cluster, thereby limiting its catalytic activity. We introduce site-selective atomic layer deposition (ALD) on porphyrins as an alternative approach to grow isolated metal oxide islands that are spatially separated. Surface-bound tetra-acid free base porphyrins (H2TCPP) may be metalated with Mn using conventional ALD precursor exposure to induce homogeneous hydroxide synthetic handles which acts as a nucleation point for subsequent ALD MnO island growth. Analytical fitting of in situ QCM mass uptake reveals island growth to be hemispherical with a convergence radius of 1.74 nm. This growth mode is confirmed with synchrotron grazing-incidence small-angle X-ray scattering (GISAXS) measurements. Finally, we extend this approach to other ALD chemistries to demonstrate the generality of this route to discrete metallo island materials.
酶催化剂的研究表明，提高催化效率的关键之一是离散尺寸的金属簇。由于传统的溶液方法容易发生聚集或需要对簇进行封端，从而限制了其催化活性，因此模拟酶簇系统在合成上具有挑战性。我们提出了在卟啉上进行选择性原子层沉积（ALD）的方法，作为生长空间分离的孤立金属氧化物岛的替代方法。通过使用常规的 ALD 前体暴露来使表面结合的四酸自由碱基卟啉（H2TCPP）与 Mn 配位，可以诱导均匀的氢氧化物合成把手，从而作为随后的 ALD MnO 岛生长的成核点。原位 QCM 质量吸收的分析拟合表明，岛的生长呈半球形，收敛半径为 1.74nm。这种生长模式通过同步辐射掠入射小角 X 射线散射（GISAXS）测量得到了证实。最后，我们将这种方法扩展到其他 ALD 化学中，以证明这种离散金属岛材料的方法具有普遍性。
