Facile control of copper nanowire dimensions via the Maillard reaction: using food chemistry for fabricating large-scale transparent flexible conductors†
Solution-grown copper nanowires (Cu NWs) are promising substitutes for vacuum deposited transparent conducting oxide films. Here, we shed new light on the synthetic chemistry of Cu NWs, showing that their formation can occur as part of Maillard's reaction, a reaction more commonly associated with food chemistry. With this newfound understanding, we adopted a generalized approach which led us to the use of non-toxic amino acids, hydrophobic amines and glucose to synthesize Cu NWs of tunable aspect ratios. The ability to tune the aspect ratio is rarely reported, and is critical in preventing the NWs from getting entangled. Consequently, we demonstrate that the well-dispersed Cu NWs could be deposited to fabricate flexible transparent conductors (TCs) on virtually any substrate, even superhydrophobic surfaces. The chemistry studied here has allowed us to circumvent prevailing methods that use hazardous hydrazine and ethylenediamine as reagents, thus opening up a new synthetic pathway towards obtaining metal NWs in an environmentally sustainable fashion.