Nitrite Reduction on Bismuth Modified Pt(111) Surfaces in Different Electrolytic Media

In this paper, the electrocatalytic enhancement of the Pt(111) surface modified with Bi adatoms towards nitrite reduction and the quantification of the catalytic effect of different adatom coverages are reported. The results were obtained in acidic and neutral media using cyclic voltammetry and in situ infrared spectroscopy measurements and show that the presence of irreversible adsorbed bismuth on Pt(111) electrodes catalyzes nitrite reduction. The presence of the foreign adatom shifts nitrite reduction to potentials as high as 0.80-0.60 V vs RHE, coinciding with the potential at which Bi undergoes its redox surface reaction. Different coverages of Bi on the surface were prepared, revealing that the activity increases with the amount of Bi until its coverage approaches half the saturation of the maximum surface blockage. For higher coverages, the activity decreases steeply, resulting in a volcano-like curve. The spectroelectrochemical experiments show that the main product of nitrite reduction at these high potentials is N2O.