Enhancing the electrocatalytic activity and stability of Prussian blue analogues by increasing their electroactive sites through the introduction of Au nanoparticles
Roger Sanchis‐Gual, Toribio F. Otero, Marc Coronado‐Puchau, Eugenio Coronado
Abstract
) with different shell sizes. Their catalytic activity is evaluated by studying the OER, which is compared to pristine PBAs and other Au-PBA heterostructures. By using the coulovoltammetric technique, we have demonstrated that the introduction of 5-10% of Au in weight in the core@shell leads to an increase in the electroactive mass and thus, to a higher density of active sites capable of taking part in the OER. This increase leads to a significant decrease in the onset potential (up to 100 mV) and an increase (up to 420%) in the current density recorded at an overpotential of 350 mV. However, the Tafel slope remains unchanged, suggesting that Au reduces the limiting potential of the catalyst with no variation in the reaction kinetics. These improvements are not observed in other Au-PBA nanostructures mainly due to a lower contact between both compounds and the Au oxidation. Hence, an Au core activates the PBA shell and increases the conductivity of the resulting hybrid, while the PBA shell prevents Au oxidation. The strong synergistic effect existing in the core@shell structure evidences the importance of the chemical design for preparing PBA-based nanostructures exhibiting better electrocatalytic performances and higher electrochemical stabilities.