Surface-Treated InP Quantum Dots for Selective CO2 Photoreduction

Abstract Photocatalytic CO2 reduction over semiconductor quantum dots (QDs) offers a promising strategy for solar fuel production, yet the influence of surface atomic structure on reaction pathways and product selectivity remains poorly understood. Herein, surface-treated indium phosphide (InP) QDs with tetrapod and tetrahedral morphologies were synthesized through a temperature-controlled hot-injection method followed by hydrofluoric acid post-treatment. Removal of the native surface oxide layer effectively suppresses charge-carrier trapping and prolongs carrier lifetimes, resulting in significantly enhanced photocatalytic CO2 reduction activity. More importantly, the product selectivity is governed by the exposed crystal facets: (110)-oriented tetrapod preferentially produces CO through a two-electron pathway, whereas (111)-oriented tetrahedron promotes further hydrogenation toward CH4. This work establishes a direct structure–reactivity relationship between surface atomic arrangement and CO2 photoreduction selectivity, providing a design principle for environmentally benign QD photocatalysts for solar fuel production.