Electric-potential-induced uniformity in graphene oxide deposition on porous alumina substrates

Abstract The unbalanced vaporizing rate of aqueous micro/nanoparticle suspensions on substrates leads to non-uniform deposition, resulting in coffee-ring effects. In this study, we developed a novel approach to suppress the coffee-ring effect of graphene oxide (GO) suspensions using simple and facile methods. To enhance the uniformity of GO deposited on porous alumina nanostructure (PAN) substrates, various droplet volumes and concentrations were employed, and an electric potential was applied. Synergistic effects between the porous PAN substrate and applied electric potential produce the most uniform GO deposition by optimizing the hydrodynamic flow in the droplet. Three critical factors affecting GO deposition uniformity were discovered: (1) the uniformity ratio, (2) the ring width, and (3) the deposition area percent. Specifically, we demonstrate that GO deposited on a PAN substrate with application of a suitable electric potential produces ultra-uniform film structures that have not been achieved using other methods. The present work provides guidelines for establishing optimized drop-casting conditions to fabricate highly uniform GO films with reduced coffee-ring effects, laying the groundwork to build large-scale and functional nanostructures for solution-based micro/nanofabrication systems.