MOF-derived PdMn and PdCo bimetallic systems as bifunctional electrocatalysts for overall water splitting

Abstract

Bimetallic Metalorganic Framework (MOF)-derived PdCo and PdMn nanoparticles have been shown to be excellent bifunctional electrocatalysts for overall electrocatalytic alkaline water splitting. Through an innovative strategy combining a soft chemical (Q) transformation followed by pyrolysis (T) of PdCo-MOF and PdMn-MOF precursors, well-defined and uniformly distributed nanoparticles supported on N-doped graphitic carbon were synthesized (PdCo-QT and PdMn-QT, respectively). The influence of the first row transition metal into the bimetallic nanoparticles on the electrocatalytic activity for both electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) was assessed. Comprehensive characterization using TEM/STEM, PXRD, Raman, XAS and XPS revealed the ultimate structural and compositional features of the synthesized materials. Notably, the bimetallic PdCo-based catalyst demonstrated the best electrocatalytic performance, exhibiting the lowest Tafel slopes for both HER and OER processes, along with superior thermodynamic and kinetic metrics compared to the bimetallic PdMn and monometallic Pd nanoparticles. The exceptional catalytic activity of the PdCo-QT electrode competes with that of benchmark materials, attributed to a synergistic effect between Pd and the secondary metal (Co), likely forming Pd–O(OH)–Co active centers. Moreover, operando and after electrocatalysis characterizations of the electrodes validate the remarkable stability and efficiency of PdCo-QT, underscoring its potential for practical water-splitting applications.