Effect of different carbon supports for Ni particles for the HER in tetra‐alkylammonium‐sulfonic acid media

Summary Vitreous carbon (VC) and pyrolytic carbon (PC) were covered by nickel particles through sputter deposition, consisting in the Ni/VC and Ni/PC electrodes, respectively. These materials were tested as cathodes in an aqueous solution of tetrafluoroborate of the 3‐triethylammonium‐propane sulfonic acid ionic liquid (TEA‐PS.BF4) for hydrogen production and characterized by scanning electron microscopy (SEM), chronoamperometry (CA), linear and cyclic voltammetry (LV and CV), and electrochemical impedance spectroscopy (EIS). The mechanism of the hydrogen evolution reaction (HER) was that of Volmer‐Heyrovsky for all the cathodes tested, and the H2 desorption at the catalytic surface is the determining step. The results indicate that different carbon supports can affect the efficiency of the particulate electrocatalyst deposited on it. The low values of H+ adsorption and the H2 desorption resistances of the modified PC system (0.43 and 0.8 Ω cm2, respectively), in relation to the modified VC system (1.13 and 7.9 Ω cm2, respectively), attest that Ni particles presence on PC favored the adsorption of H+ and H2 nanobubble desorption. The Ni particles on PC increase exchange current density (80.5 μA cm2 for Ni/PC cathode about 38.3 Ω cm2 for Ni/VC cathode) and enhance catalytic activity. These results can be attributed to the faster liberation of the active sites due to the interaction between the Ni particles and the PC support. In addition, the TEA‐PS.BF4 solution can act as a stripper, avoiding the formation of passive oxides in the open circuit and preventing the deactivation of the electrocatalyst. Vitreous carbon (VC) and pyrolytic carbon (PC) were covered by nickel particles through sputter deposition. These materials were tested as cathodes in an aqueous solution of tetrafluoroborate of the 3‐triethylammonium‐propanesulfonic acid ionic liquid (TEA‐PS.BF4) for hydrogen production. The Ni particles presence on PC favored the adsorption of H+ and H2 nanobubbles desorption, increasing exchange current density and enhance catalytic activity. The TEA‐PS.BF4 solution can avoid the formation of passive oxides, preventing the deactivationof the electrocatalyst.