Molecular Metallocorrole-Nanorod Photocatalytic System for Sustainable Hydrogen Production

Solar-driven photocatalytic generation of hydrogen from water is a potential source of clean and renewable fuel. Yet systems that are sufficiently stable and efficient for practical use have not been realized. Here, nanorod photocatalysts that have proven record activity for the water reduction half reaction were successfully combined with molecular metallocorroles suitable for catalyzing the accompanying oxidation reactions. Utilization of OH^- /⋅OH redox species as charge transfer shuttle between freely mixed metallocorroles and rods resulted in quantum efficiency that peaked as high as 17 % for hydrogen production from water in the absence of sacrificial hole scavengers. While typically each sacrificial scavenger is able to extract but a single hole, here the molecular metallocorrole catalysts were found to successfully handle nearly 300,000 holes during their lifespan. The implications of the new system on the prospects of realizing practical overall water splitting and direct solar-to-fuel energy conversion were discussed.

Modulated Binary-Ternary Dual Semiconductor Heterostructures

A generic modular synthetic strategy for the fabrication of a series of binary-ternary group II-VI and group I-III-VI coupled semiconductor nano-heterostructures is reported. Using Ag2 Se nanocrystals first as a catalyst and then as sacrificial seeds, four dual semiconductor heterostructures were designed with similar shapes: CdSe-AgInSe2 , CdSe-AgGaSe2 , ZnSe-AgInSe2 , and ZnSe-AgGaSe2 . Among these, dispersive type-II heterostructures are further explored for photocatalytic hydrogen evolution from water and these are observed to be superior catalysts than the binary or ternary semi-conductors. Details of the chemistry of this modular synthesis have been studied and the photophysical processes involved in catalysis are investigated.