Molybdenum electrodes for hydrogen production by water electrolysis using ionic liquid electrolytes

The hydrogen production by water electrolysis was tested with different electrocatalysts (molybdenum, nickel, iron alloys containing chromium, manganese and nickel) using aqueous solutions of ionic liquid (IL) like 1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4). The hydrogen evolution reaction (HER) was performed at room temperature in a potential of -1.7 V (PtQRE). A Hoffman cell apparatus was used to water electrolysis with current density values, j, between 14.6 mA cm(-2) (for Ni electrode) and 77.5 mA CM-2 (for Mo electrode). The system efficiency was very high for all electrocatalysts tested, between 97.0% and 99.2%. The energy activation values of HER was determined in an aqueous solution of BMI.BF4 10 vol.%, using platinum (23.40 kJ mol(-1)) and Mo (9.22 kJ mol(-1)) as electrocatalysts. The results show that the hydrogen production in IL electrolyte can be carried out with cheap material at room temperature, which makes this method economically attractive. (C) 2008 Elsevier B.V. All rights reserved.