A Triple Bioinspired Surface Based on Perfluorodecyl Trimethoxysilane-Coated ZnO Nanosheets for Self-Driven Water Transport in a Flow Channel

Water management is important for the bipolar plates of proton-exchange membrane fuel cells (PEMFCs), and active drainage is a desirable feature for the design of bipolar plate channels. Herein, inspired by natural micro-nanostructures, a triple bioinspired surface has been fabricated, which combines the advantages of both superhydrophobic and superhydrophilic surfaces. The superhydrophobic surface (FZnO@CA-GS) is prepared by PFTS (perfluorodecyl trimethoxysilance) coating on ZnO nanosheet-decorated arrays of microscale cylinders manufactured by photolithography, and second-round photolithography is used to convert the superhydrophobic surface into a surface with wedged superhydrophilic patterns (WSPs). Then, the water transport performance has been investigated for the WSP, where the square of the initial velocity of the droplet is found to be proportional to the wedge angle from both the theoretical calculation and experimental data. Subsequently, an index of the R value representing the flow state of droplets has been introduced to determine the optimal values for the geometrical parameters of triple-bioinspired surface (TBS) in flow channels. Such a triple bioinspired strategy affords a promising approach to fabricate bipolar plate channels with the function of self-driven water transport for PEMFC. The use of the R value in optimization may also offer insights into the design of other micro-nanostructures.