Electroactivity of NiCr Catalysts for Urea Oxidation in Alkaline Electrolyte

Inexpensive Ni‐based catalysts have shown comparable urea oxidation activity to that of precious metals in an alkaline electrolyte. We investigated the urea oxidation on binary NiCr catalysts supported on a carbon matrix in 1 m KOH and 0.33 m urea. The amount of Cr was optimized in the catalyst layer, and it was found that the catalyst with 40 % Cr (Ni 60 Cr 40 /C) exhibits the highest urea oxidation activity of 2933 mA mg Ni −1 at 0.55 V; with an onset potential of 0.32 V vs. Ag/AgCl. Chronoamperometry curves of NiCr catalysts show stability over 2000 s in oxidizing urea. A lower charge‐transfer resistance of 3.3 Ω cm 2 at 0.40 V was calculated on Ni 60 Cr 40 /C compared to that on Ni/C (13 Ω cm 2 ). The exceptionally high mass activity of Ni 60 Cr 40 /C is attributed to its improved charge‐transfer kinetics, enhanced surface coverage of Ni II /Ni III redox center, better dispersion of Ni nuclei, and a low‐Tafel slope.