Upcycling PET plastic waste into bacterial nanocellulose based electro catalyst efficient in direct methanol fuel cells

Bio-upcycling is an emerging end-of-life strategy for the polymer waste treatment that uses the power of microorganisms to biocatalyticaly convert the pre-treated polymer waste monomers into high-added materials. Poly(ethylene terephthalate) (PET), one of the leading synthetic polyesters in the global polymer market, produced from petrol based feedstock, still has no completely green alternative to meet global demand. Therefore, putting the PET based waste into a circular loop has become one of the major challenges of plastic waste management. In that context, the present study addressed the conversion of PET containing hydrolysates collected after the thermal pretreatment into bacterial nanocellulose (BNC), nowadays one of the most promising biopolymers produced in a sustainable manner. After the optimization of the BNC production cultivated under different conditions in PET hydrolysates, in a static way, the optimal conditions (yield of 3.0 mg/ml) was applied for scaling up. To further open the applicative potential of the BNC produced from PET containing plastic waste, platinum nanoparticles were deposited onto BNC developing new catalyst active in the methanol oxidation reaction. In order to enhance BNC ability to support Pt nanoparticles, it was blended with poly(vinyl alcohol), PVA, producing new PVA/BNC composites, recognized as an improved solid support, rich in hydroxyl groups that serve as an anchor points to Pt deposition. Due to the enrichment of BNC by PVA, it was possible to prepare highly active Pt-based catalyst with only 3 wt% of loaded Pt, which significantly reduce the cost of catalyst production. The cost-effective catalyst was prepared using sodium boron hydride as a reducing agent associated with film casting and fully characterized using FTIR, TGA, XRD, XPS, TEM, SEM-EDX analysis and its potential was confirmed in methanol oxidation reaction. This study explored the circular pathway from PET plastic waste to BNC and further to its potential application in direct methanol fuel cell (DMFC).