Molecular Catalysts Confined on and Within Molecular Layers Formed on a Si(lll) Surface with Direct Si-C Bonds

摘要

Catalysts play crucial roles in many chemical and energy conversion processes.'1"3' Often precious metals and rare metals are the major components of active catalysts and many efforts have been made to maximize the utilization of these atoms such as increasing their dispersion in heterogeneous catalysts. Although 100% atom efficiency is expected at molecular and single atom catalysts, molecular catalysts are usually used in solution and have limited applications because of difficulty in separating the product and catalyst. It is very difficult to prepare single atoms and maintain them without their being converted into metal clusters or particles because they are more energetically stable.' One would expect, however, that if the metal complexes are confined on or within a solid substrate at well isolated positions, they may act as molecular catalysts without aggregation. Confined molecular catalysts can be used as heterogeneous catalysts and can easily be separated from the product. Here we demonstrate that if Pt complexes are placed at controlled positions on and within molecular layers, utilizing the concept of "surface nanoarchitectonics", they act as confined molecular electro-catalysts for hydrogen evolution at a semiconductor electrode surface without being converted into metal clusters or particles.