From PET Bottles Waste to N-Doped Graphene as Sustainable Electrocatalyst Support for Direct Liquid Fuel Cells

Abstract

Direct liquid fuel cells represent one of the most rapidly emerging energy conversion devices. The main challenge in developing fuel cell devices is finding low-cost and highly active catalysts. In this work, PET bottle waste was transformed into nitrogen-doped graphene (NG) as valuable catalyst support. NG was prepared by a one-pot thermal decomposition process of mineral water waste bottles with urea at 800 °C. Then, NG/Pt electrocatalysts with Pt loadings as low as 0.9 wt.% and 1.8 wt.% were prepared via a simple reduction method in aqueous solution at room temperature. The physical and electrochemical properties of the NG/Pt electrocatalysts are characterized and evaluated for application in direct borohydride peroxide fuel cells (DBPFCs). The results show that NG/Pt catalysts display catalytic activity for borohydride oxidation reaction, particularly the NG/Pt_1, with a number of exchanged electrons of 2.7. Using NG/Pt composite in fuel cells is anticipated to lower prices and boost the usage of electrochemical energy devices. A DBPFC fuel cell using NG/Pt_1 catalyst (1.8 wt.% Pt) in the anode achieved a power density of 75 mW cm−2 at 45 °C. The exceptional performance and economic viability become even more evident when expressed as mass-specific power density, reaching a value as high as 15.8 W mgPt−1.