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 desired for practical applications; clearly such efforts are extremely challenging. Here, we show the CRE suppression with undetectable disturbance of the deposit on carbon-based surfaces. This is achieved by adding ammonium bicarbonate (NH₄HCO₃), benefited from the dissociation of NH₄HCO₃ to produce NH₄⁺, together with its decomposition into NH₃ and CO₂ molecules. Surprisingly, NH₄⁺ can also function as Na⁺/K⁺ to suppress CRE through the cation- interactions although its hydrate state is only partially positively charged. We further successfully apply this approach to enhance the morphology, resistance, and color uniformity for the deposits of graphene oxide quantum dots, conductive inks, and organic dyes, respectively. Our work provides a practical strategy to improve the performance of the fabricated devices, paving the way for the development of high-accuracy manufacturing techniques in diverse industries.