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

Abstract 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.