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

Abstract 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 (NH₄HCO₃), which benefits from the dissociation of NH₄HCO₃ to produce ${\mathrm{NH}}_4^{+}$, as well as its decomposition into NH₃ and CO₂ molecules. Surprisingly, ${\mathrm{NH}}_4^{+}$ 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.