Electrochemical Dehydrogenation of Piperazine on Pd-Based Multimetallic Alloy Catalysts

Hydrogen, an essential clean energy carrier, poses challenges in terms of efficient and scalable storage. Liquid organic hydrogen carriers (LOHCs) have gained attention as viable chemical media for hydrogen storage and release, providing advantages such as high energy density and compatibility with zero-emission fuel cells. Nevertheless, a critical bottleneck is the development of cost-effective and stable electrocatalysts for LOHC dehydrogenation, particularly using noble metal catalysts such as Pd, which suffer from high costs and limited durability. In this study, we demonstrate that Pd-based multimetallic alloy nanoparticles on carbon (Pd-M/C, where M = Pt, Ag, Cu, and Ru), synthesized via a Couette–Taylor reactor, demonstrate enhanced electroactivity and stability for piperazine oxidation, a model for LOHC dehydrogenation. Among these, Pd₇₁Cu₂₉/C shows the optimal electronic structure, achieving a specific activity of 20.50 mA cm^–2─1.8 and 2.68 times higher than commercial Pd/C and Pt/C benchmarks, respectively. Density functional theory (DFT) calculations coupled with gas chromatography–mass spectrometry (GC–MS) analysis of reaction intermediates elucidate the electrocatalytic dehydrogenation pathway. These studies reveal that Pd–Cu alloying synergistically modulates the electronic structure via interatomic charge redistribution.