Enhanced redox catalysis of electrochemical alcohol oxidation in alkaline medium by using Pt-Cu/C catalyst

Abstract

In electrochemical alcohol oxidation reactions catalysed by supported Pt-based nanoparticles, the catalytic performance is highly correlated with the electron density accumulated over the metal’s surface. The highly electronegative nature of Pt, affects the catalytic performance by accumulating electrons generated over the oxidative reaction on the Pt surface. It was found that alloying Cu to Pt enhances greatly the catalyst’s activity and robustness. This enhancement is due to the redox reaction of Cuδ+ species into Cu0 with the electrons generated during the reaction. Here, we show that an oxidative pretreatment of the carbon support XC-72R with HNO3 or H2O2 can further boost the catalysis of alcohol oxidation. This is mainly explained by the effect of enriched O-containing functional groups introduced in the support materials, which stabilize the presence of Cuδ+ species in the bimetallic Pt-Cu nanoparticles. This process increases the hydrophilic wettability, which enables more adsorption of reactant molecules and hydroxide ions over the catalyst’s surface, as demonstrated by DFT calculations. The proposed catalytic system is applicable to a variety of substrates, including methanol, ethanol, isopropanol and sorbitol. Our work emphasizes the importance of support’s modification in tuning the interaction within the bimetallic nanoparticles and thus enhancing the electrocatalytic oxidation reactions’ activity.