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

• Bifunctional electrocatalyst of Pd decorating P, N-codoped carbon nanostructures. • A hybrid acid/alkali cell for energy-saving and self-powered generation of H 2. • Indirect releasing H 2 stored in hydrazine by an electrochemical strategy. • Efficient, controllable and continuous release high-purity H 2 from H 2 carrier. Liquid-phase hydrogen (H 2) carriers have received widespread attention owing to their convenient and safe storage and transportation of H 2. Among the various liquid-phase H 2 carriers, hydrazine (N 2 H 4) shows promising applications due to its ability to release H 2 in aqueous solutions via the dehydrogenation process with the assistance of suitable catalysts, which yet produces N 2 /H 2 mixture gas and thus require additional high-energy purification process. In this work, we propose a self-powered electrochemical strategy to indirectly release high-purity H 2 stored in N 2 H 4 by developing a hybrid acid/alkali electrochemical cell, which is set up by coupling alkaline anode for N 2 H 4 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 H 2 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 H 2. [ABSTRACT FROM AUTHOR]