Selective electrocatalytic hydrogenation of nitrobenzene over copper-platinum alloying catalysts: Experimental and theoretical studies

We report ultrafine CuxPty alloying nanoparticles anchored on carbon black (CuxPty/C) for selective electrocatalytic hydrogenation of nitrobenzene (Ph-NO2) at ambient conditions. The experimental and theoretical studies reveal that as electrocatalyst, the optimal Cu3Pt/C with adjusted electronic structure can effectively facilitate the adsorption and activation of Ph-NO2. The results indicate that the acidic media is favorable for the production of aminobenzene irrelevant to the applied potential, while the electrocatalytic hydrogenation products are highly dependent on the reduction potential in the alkaline media. As a result, the Cu3Pt/C can afford almost 100 % conversion of Ph-NO2 into azoxybenzene with ∼99 % selectivity at 0.3 V (vs. RHE) and aminobenzene with ∼99 % selectivity at -0.3 V (vs. RHE) in 1.0 M KOH, respectively. The theoretical calculations provide a comprehensive understanding of the selective electrocatalytic hydrogenation mechanisms of Ph-NO2 relative to electrolyte pH and applied potential, matched well with the experimental results.