Effects of heated-treating temperature on the stability and electrochemical performance of alginate-based...

In this study, the organosilane nanoparticles as additive and crosslinker were prepared and incorporated into sodium alginate to fabricate a series of alginate-based multi-crosslinked biomembranes at different thermal treatment temperature without the usage of another crosslinking agent. The effects of treatment temperature on the stability of biomembranes including dimensional, oxidative, hydrolytic and mechanical stability were investigated in detail. As a whole, the stability of biomembranes exhibited increasing tendency with the increment of treatment temperature due to the formation of more compact internal network structure. The electrochemical performance of biomembranes in respect to their potential as proton exchange membranes for direct methanol fuel cell application were also investigated based on the treatment temperature. The results revealed that the biomembranes possessed excellent methanol resistance and the methanol diffusion coefficient decreased with the increment of treatment temperature. The biomembrane with 120 °C heat-treatment showed the optimal selectivity (14.30 × 10⁵ Ss cm^-3), which was about 1.77 and 68.10 times of that and of M-80 (8.09 × 10⁵ Ss cm^-3) and Nafion^@117 (0.21 × 10⁵ Ss cm^-3), respectively. Fuel cell performance measurements showed that M-120 possessed higher maximum power density and cell stability compared with M-80 and Nafion^@117, indicating its best adaptability for use in direct methanol fuel cell.