Electro-oxidation of ammonia on electrochemically roughened platinum electrodes

With the recent advances in sustainable ammonia production, the ammonia oxidation reaction (AOR) has gained interest. In this work, we present an evaluation of the performance of electrochemically roughened platinum electrodes (Pt_R) for aqueous AOR. Platinum electrodes were modified using square wave voltammetry at various frequencies in 0.5 M H₂SO₄. Platinum electrodes modified at frequencies in excess of 1 kHz tended to develop nano-structured surfaces with corresponding increases in the proportion of the active {311} phase of platinum resulting in improved AOR activity. Of the different surface structures formed by the roughening process, trigonal nano-pyramids (TNPs) with small average cross sections of 20 ± 5 nm showed the greatest degree of enhancement (550% increase in peak current density relative to polycrystalline platinum. With further optimization of these roughening techniques, Pt_R electrodes may prove useful in as anodes in ammonia sensing applications and in fuel cells.