Self-healable, Tolerant Superaerophobic Coating for Improving Electrochemical Hydrogen Production

Gas-evolving electrodes often suffer from the blocking of catalytic active sites-due to unwanted and unavoidable adhesion of generated gas bubbles, which elevates the overpotential for the electrochemical hydrogen evolution reaction (HER)- by raising the resistance of the electrode. Here, a catalyst-free and self-healable superaerophobic coating having ultra-low bubble adhesion is introduced for achieving significantly depleted overpotentials of 209 and 506 mV at both low (50 mA cm^-2) and high (500 mA cm^-2) current densities, respectively, compared to a bare nickel-foam electrode. The optimized coating ensured an early detachment of the generated tiny (0.8 ± 0.1 mm) gas bubble-and thus, prevented the undesired rise in resistance of the coated electrode. The systematic association of physical (i.e., ionic interactions, H-bonding, etc.) cross-linkage, β-amino ester type covalent cross-linkage and reinforced halloysite nano clay enables the design of such functional material embedded with essential characteristics-including improved mechanical (toughness of 63.7 kJ m^-3, and tensile modulus of 26 kPa) property and chemical (extremes of pH (1 and 14), salinity, etc.) stability, rapid (<10 min) self-healing ability (even at alkaline condition) and desired bubble-wettability (bubble contact angle of 158.2 ± 0.2^°) with ultralow force (4.2 ± 0.4 µN) of bubble adhesion.