Size-Dependent Photocatalysis by Wurtzite InP Quantum Dots Utilizing the Red Spectral Region
David Stone, Shira Gigi, Tom Naor, Xiang Li, Uri Banin
Abstract
High Resolution Image Download MS PowerPoint Slide Photocatalytic hydrogen generation offers a sustainable method for generating solar fuels. Indium phosphide (InP) nanocrystal quantum dots (QDs), with their adjustable band gaps and versatile surface properties, present an eco-friendly alternative to heavy-metal-based semiconductor NCs as photocatalysts. We report the synthesis of wurtzite InP (w-InP) QDs and their performance as photocatalysts for hydrogen generation from water by using the red part of the solar spectrum. Size-controlled w-InP QDs with absorption edges extending to 750 nm were synthesized via a cation exchange route. Stabilized in water with sulfides, these QDs demonstrated higher hydrogen generation efficiencies compared with other narrow-band-gap QDs. The overall hydrogen generation efficiency sharply decreases with the size. A mixed-size approach combining the high efficiency of small QDs with the broad absorption range of large QDs enhances the solar-to-hydrogen conversion by a more effective utilization of the solar spectrum. Such an approach shows promise for effective solar fuel generation.