Ultrahigh-throughput cross-flow filtration of solution-processed 2D materials enabled by porous ceramic membranes

Printed electronics is a disruptive technology in multiple applications
including environmental and biological sensors, flexible displays, and
wearable diagnostic devices. With superlative electronic, optical,
mechanical, and chemical properties, two-dimensional (2D) materials are
promising candidates for printable electronic inks. While liquid-phase
exfoliation (LPE) methods can produce electronic-grade 2D materials,
conventional batch separation processes typically rely on centrifugation,
which requires significant time and effort to remove incompletely
exfoliated bulk powders, hindering the scale-up of 2D ink manufacturing.
While cross-flow filtration (CFF) has emerged as a promising continuous
flow separation method for solution-processed 2D nanosheets, previously
demonstrated polymer CFF membranes necessitate low 2D nanosheet
concentrations to avoid fouling, which ultimately limits mass throughput.
Here, we demonstrate a fully flow-based, exfoliation-to-ink system for
electronic-grade 2D materials using an integrated cross-flow separation
and concentration system. To overcome the relatively low-throughput
processing concentrations of incumbent polymer CFF membranes, we employ
porous ceramic CFF membranes that are tolerant to 10-fold higher nanosheet
concentrations and flow rates without compromising separation efficiency.
Furthermore, we demonstrate a concentration method via cross-flow
ultrafiltration, where the retentate can be directly formulated into
printable inks with electronic-grade performance that meets or exceeds
centrifugally produced inks. Life cycle assessment and technoeconomic
analysis quantitatively confirm the advantages of ceramic versus polymer
CFF membranes including reductions of 97%, 96%, 94%, and 93% for
greenhouse gas emissions, water consumption, fossil fuel consumption, and
specific production costs, respectively. Overall, this work presents an
environmentally sustainable and cost-effective solution for the
fabrication, separation, and printing of electronic-grade 2D materials.