(732v) Scale-up of Continuous Manufacturing and Productization of Graphene for Advanced Respirator and Biosensor Applications

Pristine, non-oxidized graphene has vast potential in numerous applications including advanced respirators and biosensors which can mitigate the devastation of future respiratory pandemic outbreaks. Specifically, higher quality respirators with better breathability to protect wearers and easy-to-use biosensors that reliably detect different types of pathogens will be critical during any future coronavirus or other outbreaks. Graphene-enhanced filters and sensors offer the promise to deliver these new tools. However, large-scale production for such strict quality control graphene has remained a challenge, and the limited supply of graphene is costly and dominated by overseas product of questionable or unacceptable quality. There is a critical need for large, thin and nearly defect free (LTDF) graphene flakes manufactured domestically at a price point that allows for democratization of this advanced material. The focus of this work is on scaling up a patented electrochemical exfoliation and post-treatment process to convert commercial-grade graphite to fully reduced graphene flakes of high structural purity, and testing the product in two critical coronavirus applications: affordable, high performance, breathable N98+ graphene-based filtration masks and low cost, accurate graphene-based biosensors to detect live coronavirus in situ. Southwest Research Institute (SwRI) has tested, validated, and optimized a bench top electrochemical reactor for small-scale (~200 mg) batch production of pristine LTDF graphene flakes. SwRI has performed quality control and quality assurance which includes characterization techniques such as powder X-ray diffractometry (PXRD), Raman spectroscopic microanalysis, Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS). These techniques confirm that the graphene is thin (< 5 atomic layers), non-oxidized, and nearly defect-free with large flake area (avg. 55 μm2). Aggregation of graphene flakes is a challenge, and preliminary efforts to suspend the graphene flakes with various solvents has resulted in > 40% of the graphene flake product being dispersed for weeks without settling or aggregating. Based on lessons learned from the small-scale reactor, SwRI is currently designing a medium-scale electrochemical reactor with 10x capacity to produce up to 2 grams of graphene per batch. At this scale, sufficient graphene can be provided to Flextrapower, Inc to further develop their advanced filtering and respirators, and to University of Arkansas to test with their biosensors. The ultimate goal of the project is to model, simulate, design, and construct a pilot-scale, continuous-flow reactor for large-scale synthesis, isolation, and purification of defect-free graphene flakes.