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3D printing and carbonisation is used to produce designed gas diffusion layer materials for polymer electrolyte membrane fuel cells (PEMFC). Using a desktop UV 3D printer, designed porous microstructures are printed with micro and macro-scale features. Successful improvement of the pyrolysis process maintains the structural accuracy during carbonisation, reducing the material to electrically conductive carbon. The size of the material allows for testing in a lab scale fuel cell with 1.5 × 1.5 cm electrode size, which shows lower but interesting electrochemical performance (power density of 205 mW cm−2). Challenges associated with integration of a 3D printed structure into a membrane electrode assembly are highlighted, including the low open circuit voltage caused by large amounts of membrane deformation and subsequent hydrogen crossover. This study shows that it is possible to design and manufacture a gas diffusion layer for fuel cells. Numerical simulation on the new GDL structure shows that advective-diffusive transport of oxygen in the 3D printed design is superior to conventional carbon paper. This study serves as the first attempt to implement 3D printed microstructures as GDL into PEMFC. [Display omitted] • A designed carbon gas diffusion layer is manufactured using 3D printing. • Controlled pyrolysis is used to preserve microstructure. • Challenges for 3D printed materials integrated into fuel cells are highlighted. • Simulations show an 8% higher oxygen concentration at the catalyst layer. [ABSTRACT FROM AUTHOR]

In this work, a 3D-printed reactor was designed to enable natural graphite flakes to be used for electrochemical exfoliation to quickly obtain graphene oxide. Graphite foil as a typical raw material of electrochemical exfoliation was also exfoliated for comparison. Under the same conditions (10 V, 1 mol L-1 ammonium sulphate solution as electrolyte), the graphene products obtained by one-step electrochemical exfoliation using natural graphite flakes based on the reactor, have a significantly higher degree of oxidation than products obtained using graphite foil (the oxygen content is increased by 50.2%). In addition, the degree of oxidation can be further increased by increasing the electrolyte concentration or reaction time. This design achieves one-step exfoliation using natural graphite flakes to obtain graphene oxide with tunable oxygen content in short time without using any strong oxidants or strong acids. The as-prepared electrochemically exfoliated graphene oxide (EGO) was used to prepare polybenzimidazole (PBI)/graphene oxide (GO) composite membranes for high-temperature polymer electrolyte membrane fuel cells (HTPEMFC). The 0.5%, 1% and 2% EGO loadings in the PBI membrane increased the peak power density by 13.8%, 24.4% and 29.2%, respectively. Image 1 • The use of natural graphite flakes as raw materials for electrochemical exfoliation. • No oxidant and acid used to obtain graphene oxide. • A novel reactor design achieves the above goals. • Electrochemically exfoliated graphene oxide enhances the performance of PBI membrane. [ABSTRACT FROM AUTHOR]