Key Parameters Controlling the Performance of Catalytic Self-Pumping Membranes

Abstract

Previous studies have demonstrated that a membrane coated with Pt and Au on opposing sides will pump liquid through its pores via catalytic reactions of fuels like H2O2. A membrane pore of such a catalytic membrane was studied via 2D axisymmetric modeling, which solved the Poisson-Nernst-Planck-Stokes equations in COMSOL 5.5. We used a validated model from our prior work and varied key parameters, including the pH value, pore radius, porosity, and pore length, to examine their effect on self-pumping flow rates. The results show that the self-pumping flow rate is most sensitive to pore radius and the operating pH value, followed by porosity (pore area fraction) and pore length. The trade-off between increased ionic current and increased ionic strength can be balanced by tuning these parameters, contributing to optimum self-pumping performance. A membrane with a pore radius of 5 μm, porosity of 20%, and pore length of 10 μm obtained an optimum membrane-average flow velocity of 2.6 μm/s when operating under a pH 7 environment, which is an improvement of over 100% over the maximum experimentally demonstrated velocity. The results highlight the potential of utilizing catalytic reactions to manipulate liquid via membranes/microchannels without external power. Guidelines for the design of the catalytic self-pumping membrane/microchannel are proposed at the end.