Microscale Templating of Functional Particles Using Self‐Limiting Electrospray Deposition

Electrospray deposition (ESD) uses strong electric fields applied to solutions and dispersions exiting a capillary to produce charged monodisperse droplets driven toward grounded targets. Self-limiting electrospray deposition (SLED) is a phenomenon in which highly directed, uniform, and even 3D coatings can be achieved by trapping charge in the deposited film, redirecting the field lines to uncoated regions of the target. However, when inorganic particles are added to SLED sprays, the buildup of charge required to repel incoming material is disrupted as particle loading increases. Due to its fibril gelling behavior, methylcellulose (MC) SLED can form nanowire morphologies. These wires, when used as a binder, can separate particles and prevent percolation. In this work, a variety of conductive and insulating particles are explored using patterned and un-patterned substrates. This exploration allows us to maximally load particles for high-concentration and highly controlled self-limiting functional sprays. This is demonstrated using Ti₃C₂T_x MXene to functionalize an interdigitated electrode for use as a supercapacitor.