Large-Area Monocrystalline Copper Microflake Synthesis

Copper is one of the most extensively studied materials for energy conversion and catalytic systems, with a wide range of other applications, from nanophotonics to biotechnology. However, existing synthesis methods are limited with many undesirable byproducts and poorly defined morphologies. Here, we report an on-substrate wet synthesis approach that yields purely metallic and monocrystalline Cu microflakes with an exposed (111) crystalline surface. By systematically studying the growth mechanism, we achieve unprecedented sizes of more than 130 μm, which is 2 orders of magnitude larger than reported in most previous studies, along with high aspect ratios of over 400. Furthermore, we show significantly higher stability against oxidation provided by the halide adlayer, which also eliminates the need for any organic surfactants in the synthesis. Overall, our facile synthesis approach delivers an exciting avenue for the emerging fields of catalysis and nanophotonics.