Halide-Mediated Phase Control of Fe_xCo_1–xC_y Nanoparticles

The ability to control the compositional phase in first row transition metal bimetallic carbides as well as systematically controlling the metal ratio is complicated by the rich phase diagram, differences in metal reactivity, and differences in carbon solubility in the first-row metal carbides. Prussian blue analogues (PBAs) have been shown to act as a single source precursor for the formation of nanocrystal metal carbides with maintenance of their metal. An investigation of crystal phase control in the ternary (Fe x Co 1– x ) y C z formed by PBA collapse is yet to be explored. In this study, we demonstrate the ability to tune phase (from most carbon rich to least carbon rich) M 2 C, M 5 C 2, M 7 C 3, and M 3 C, as well as the bimetallic alloy (M) in bimetallic FeCo nanocarbides through a strategy that pairs synthetic and density functional theory approaches to enable future targeted structure–function research on intriguing catalytic, therapeutic, and magnetic applications.