Chalcogenide and pnictide nanocrystals from the silylative deoxygenation of metal oxides

Abstract

Transition metal chalcogenide and pnictide nanocrystals are of interest for optoelectronic and catalytic applications. Here, we present a generalized route to the synthesis of these materials from the silylative deoxygenation of metal oxides with trimethylsilyl reagents. Specific nanophases produced in this way include Ni₃S₂, Ni₅Se₅, Ni₂P, Co₉S₈, Co₃Se₄, CoP, Co₂P, and heterobimetallic (Ni/Co)₉S₈. The resulting chalcogenide nanocrystals are hollow, likely due to differential rates of ion diffusion during the interfacial phase transformation reaction (Kirkendall-type effect). In contrast, the phosphide nanocrystals are solid, likely because they form at higher reaction temperatures. In all cases, simultaneous partial decomposition of the deoxygenating silyl reagent produces a coating of amorphous silica around the newly formed nanocrystals, which could impact their stability and recyclability.