화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.161, No.1, E12-E22, 2014
Hydrogen Evolution Reaction Kinetics on Electrodeposited Pt-M (M = Ir, Ru, Rh, and Ni) Cathodes for Ammonia Electrolysis
Metallic and bimetallic electrocatalysts of the type PtxM1-x (where M = Ru, Rh, Ir, Ni) electrodeposited on carbon fiber paper were evaluated as electrocatalysts for the hydrogen evolution reaction (HER) in an ammonia electrolytic cell. The addition of 1 M ammonia resulted in an increase in the HER overpotential for all electrocatalysts except Rh. The bimetallic electrocatalysts offer higher HER activity compared to metallic ones with the trend Pt-Ir > Pt-Rh > Pt-Ru > Pt-Ni. The enhanced activity of the bimetals is attributed to the synergistic activity. Ammonia adsorption is specific to the more electropositive alloying material, leaving the Pt sites active for hydrogen underpotential deposition and HER. Increasing the loading by a factor of two resulted in a decrease in the pore size thereby leading to a poor three-phase electrocatalyst, which in-turn causes a decrease in the HER electrocatalytic activity in the presence and absence of 1 M ammonia. Maximum electrocatalytic activity was achieved with a Pt-Ir electrocatalyst with a loading (Me / [Me + Pt]) of 13%, a Pt content of 68% and an intercrystallite distance of 7.2 nm. (C) 2013 The Electrochemical Society.