Size-Dependent\nPhotocatalysis by Wurtzite InP Quantum\nDots Utilizing the Red Spectral Region

Photocatalytic hydrogen generation offers a sustainable\nmethod\nfor generating solar fuels. Indium phosphide (InP) nanocrystal quantum\ndots (QDs), with their adjustable band gaps and versatile surface\nproperties, present an eco-friendly alternative to heavy-metal-based\nsemiconductor NCs as photocatalysts. We report the synthesis of wurtzite\nInP (w-InP) QDs and their performance as photocatalysts for hydrogen\ngeneration from water by using the red part of the solar spectrum.\nSize-controlled w-InP QDs with absorption edges extending to 750 nm\nwere synthesized via a cation exchange route. Stabilized in water\nwith sulfides, these QDs demonstrated higher hydrogen generation efficiencies\ncompared with other narrow-band-gap QDs. The overall hydrogen generation\nefficiency sharply decreases with the size. A mixed-size approach\ncombining the high efficiency of small QDs with the broad absorption\nrange of large QDs enhances the solar-to-hydrogen conversion by a\nmore effective utilization of the solar spectrum. Such an approach\nshows promise for effective solar fuel generation.