I-004

Germano Tremiliosi-Filho

germano@iqsc.usp.br

S. I. Venturini, C. A. D. Rodriguez, H. Varela

Chemistry Institute of São Carlos, University of São Paulo, Brazil

Metal Borides for Ethanol-Assisted Water Electrolysis

Hydrogen plays an important role in the decarbonization strategy. Unfortunately, the most common method for industrial hydrogen production is by high-temperature steam reforming of methane or other hydrocarbons that contributes to the carbon emissions. On the other hand, ethanol can assist hydrogen production at lower temperatures and voltages, i.e., at lower energy cost than conventional water electrolysis. In the ethanol-assisted electrolytic hydrogen production process, alcohol is simply added to the anode compartment of a polymer electrolyte membrane electrolyzer, so, replacing the oxygen evolution reaction by the ethanol electro-oxidation while in the cathode compartment only the hydrogen evolution reaction occurs. 

Thus, in this work will be discussed the development a new class of catalytic material, specially for hydrogen production, with a special characteristic, that is the insensibility to ethanol reduction, that compromises the efficiency of hydrogen production, due to the ethanol membrane crossover. Thereby, intermetallic compounds based on nickel and boron, NixByMz (M = Co, Fe, Mo, etc) were prepared. The synthesis method was the powder metallurgy, where the metallic components were griding in a high energy ball mill in argon atmosphere. After grinding, the materials were heat treated at various temperatures under inert argon atmosphere, in order to form the intermetallic compound according to each specific phase diagram. All catalysts were characterized by X-ray diffraction, TEM and SEM. The catalysts were tested for hydrogen evolution reaction (HER) in alkaline medium (4 M KOH in the cathode compartment). In the anodic compartment, the same solution was used after addition of 1 M ethanol. The measurements were done at the temperature range of 25 – 85 oC. The measurements were made in an electrolysis metallic bench cell with electrodes of 5 cm2 of area and a gap between electrodes of 2 mm. The activity of Ni2B, NiMoB and NiCoB for the HER was very good and similar to the Pt electrode and was not affected by the presence of ethanol in the cathode compartment. On the other hand, the HER on Ni3B was inhibited in presence of ethanol.

Acknowledgements: CNPq, FAPESP, Shell and RCGI.