Synthesis and Electrochemical Study of Pd-Based Trimetallic Nanoparticles for Enhanced Hydrogen Storage

Abstract

The success of acceptable hydrogen storage capacities on high surface area carbon materials at ambient temperature requires the combination of both physisorption and chemisorption. Despite the sole reliance on physisorption for hydrogen uptake in carbon, the dispersal of transition metal catalysts on carbon materials significantly enhances hydrogen uptake at ambient temperatures, via the process of hydrogen spillover. In the present study, hydrogen electrosorption onto activated carbon materials modified with different trimetallic dissociation catalysts (Pd–Ag–Cd) was investigated in an acidic medium using cyclic voltammetry and chronoamperometry. A significant synergistic effect on hydrogen storage was observed, which could be attributed to the electrochemical reduction of hydrogen ions initially at the Pd-based nanoparticles and the hydrogen surface diffusion subsequently to the activated carbon. Utilizing electrochemical methods, the optimized composition of the Pd–Ag–Cd alloys was determined to be Pd80Ag10Cd10, with the highest hydrogen sorption capacity at a hydrogen desorption charge of 18.49 C/cm2·mg. With increased kinetics and a decrease in the phase transition, the significant enhancement of hydrogen sorption, in comparison to the Pd–Ag and Pd–Cd bimetallic alloys, was further demonstrated, making Pd–Ag–Cd catalysts attractive for use as hydrogen dissociation catalysts for applications in both hydrogen purification and storage.