Suppression of the Coffee Ring Effect with Undetectable Disturbance of the Deposit

Suppressing the coffee ring effect (CRE) of an aqueous suspension through manipulation without affecting the remaining deposit is highly desirable for practical applications; however, this is extremely challenging. Here, we demonstrate CRE suppression with undetectable disturbance of the deposit on carbon-based surfaces. This was achieved by adding ammonium bicarbonate (NH_4HCO_3), which benefits from the dissociation of NH_4HCO_3 to produce NH_4^+, as well as its decomposition into NH_3 and CO_2 molecules. Surprisingly, NH_4^+ can also function as Na^+/K^+ to suppress the CRE through cation interactions, although its hydrate state is only partially positively charged. Moreover, we successfully applied this approach to enhance the morphology, resistance, and color uniformity of deposits of graphene oxide quantum dots, conductive inks, and organic dyes, respectively. This study provides a practical strategy for improving the performance of fabricated devices and paves the way for the development of high-accuracy manufacturing techniques in diverse industries.