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• 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]

A bifunctional electrode with 1D nickel–iron phosphide and molybdenum dioxide (NFPMO) grown on nickel foam presents highly outstanding electrocatalytic performance for overall water splitting. • Electrode of NiFeP-MoO 2 hybrid nanorods on Ni foam for water electrolysis. • High-activity and high-stability electrocatalyst towards HER and OER. • The voltage for water splitting at j = 10, 100 mA cm−2 is only 1.41 V and 1.65 V. The research about inexpensive and efficient electrocatalyst plays a significant role in electrocatalyzing H 2 production from water splitting. We herein report a novel hybrid 1D heterogeneous nanorods based on nickel–iron phosphide and molybdenum dioxide (NFPMO) grown on nickel foam that presents highly outstanding electrocatalytic performance in electrochemical overall water splitting, both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The applied cell voltage of employing NFPMO electrode in overall water splitting merely require 1.41 V and 1.65 V at 10 mA cm−2 and 100 mA cm−2 working electrolysis current density, respectively, and it can bear high stably upon hundreds of hours long-term electrolysis operation. The synergistic effects of heterogeneous structure in 1D nanorods obviously accelerate the electrocatalytic activity, as demonstrated by not only electrochemical tests but also coupling systematic electrochemical study with density functional theory (DFT) calculation. [ABSTRACT FROM AUTHOR]