Nanostructured LaNiO 3 Perovskite Electrocatalyst for Enhanced Urea Oxidation
Robin P. Forslund, J. Tyler Mefford, William G. Hardin, Caleb T. Alexander, Keith P. Johnston, Keith J. Stevenson
Abstract
Urea electrooxidation has attracted considerable interest as an alternative anodic reaction in the electrochemical generation of hydrogen due to both the lower electrochemical potential required to drive the reaction and also the possibility of eliminating a potentially harmful substance from wastewater during hydrogen fuel production. Nickel and nickel-containing oxides have shown activities comparable to those of precious-metal catalysts for the electrooxidation of urea in alkaline conditions. Herein, we investigate the use of nanostructured LaNiO 3 perovskite supported on Vulcan carbon XC-72 as an electrocatalyst. This catalyst exhibits an exceptionally high mass activity of ca. 371 mA mg ox –1 and specific activity of 2.25 A mg –1 cm ox –2 for the electrooxidation of urea in 1 M KOH, demonstrating the potential applications of Ni-based perovskites for direct urea fuel cells and low-energy hydrogen production. While LaNiO 3 is shown to be stable at low overpotentials, through in-depth mechanistic studies the catalyst surface was observed to restructure and there was apparent CO 2 poisoning of the LaNiO 3 upon extended cycling, a result that may be extended to other Ni-based systems.