Highly efficient photocatalysts from nanoscale metal/semiconductor/metal heterojunctions
Photocatalyst-mediated photoelectrochemical processes can utilize photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in visible light range, or insufficient photoelectrochemical stability. Metal/semiconductor/metal heterostructures are designed and synthesized as highly efficient and stable photocatalysts by integrating a nanoscale Schottky photodiode encased in a protective insulating shell with two exposed metal catalysts. As an example, Pt/Si/Ag nanowire heterostructures are synthesized to exhibit efficient photocatalytic activity for a wide range of thermodynamically downhill and uphill reactions, including photocatalytic degradation of organic dyes and toxic pollutants, reduction of metal ions and carbon dioxide, as well as hydrogen generation.