Self-powered H2 generation implemented by hydrazine oxidation assisting hybrid electrochemical cell

Liquid-phase hydrogen (H2) carriers have received widespread attention owing to their convenient and safe storage and transportation of H2. Among the various liquid-phase H2 carriers, hydrazine (N2H4) shows promising applications due to its ability to release H2 in aqueous solutions via the dehydrogenation process with the assistance of suitable catalysts, which yet produces N2/H2 mixture gas and thus require additional high-energy purification process. In this work, we propose a self-powered electrochemical strategy to indirectly release highpurity H2 stored in N2H4 by developing a hybrid acid/alkali electrochemical cell, which is set up by coupling alkaline anode for N2H4 electrooxidation reaction (HzOR) with acidic cathode for hydrogen evolution reaction (HER), respectively. For this purpose, Pd nanoparticles uniformly decorating P, N-codoped hollow dodecahedron carbon nanostructures (Pd/PNC) is prepared as bifunctional electrocatalyst for both HzOR and HER, which exhibits high electrocatalytic activity and robust stability. Density functional theory (DFT) calculations imply that P, N-codoping substrate of Pd is conductive to optimize adsorption/desorption sites upon electrocatalysis of HzOR and HER by lowing Gibbs free energy and improving activity. The as-assembled hybrid acid/alkali cell is capable of delivering a maximum power density of 18.2 mW cm-2 and can run stably for 120 h, implementing H2 generation in a voltage or power controllable manner. This work may inspire exploring the way for efficient, energy-saving, and continuous generation of high-purity H2.