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A 3D self-supported hierarchical architecture composed of Ni nanoparticle@nitrogen-doped carbon nanotube modified NiMoN micro-pillar arrays grown on Ni foam (Ni@NCNT/NiMoN/NF) was synthesized. Benefiting from the protection by N-doped carbon layers, and the well-designed hierarchical structure with a large surface area, high electrical conductivity and convenient mass/electron transfer paths, this composite shows excellent activity and durability under both acidic and alkaline conditions. It demands extremely low overpotentials of 15 mV and 156 mV in 1.0 M KOH, and 31 and 96 mV in 0.5 M H2SO4 to achieve current densities of 10 and 200 mA cm−2, respectively, which are superior to those for commercial Pt/C and other control samples. DFT calculations prove that the synergetic effect between N-doped carbon, Ni, and NiMoN enhances H2O adsorption and decreases hydrogen adsorption free energy (|ΔGH*|) to facilitate the HER process. Furthermore, the composite possesses extraordinary antioxidation ability under the conditions of the cyclic current pulse and power-off–on state. This work suggests an effective pathway to enhance the catalytic activity and oxidation resistance by building a hierarchical structure encapsulated by thin N-doped carbon layers, showing promising potency as the HER electrode in practical energy conversion and storage systems of wind power and solar power.

Hydrogen-motivated electrolysis of Na2CO3 for energy-saving production of NaOH and CO2/NaHCO3 is realized by the hydrogen oxidation reaction to insert proton into anolyte and the hydrogen evolution reaction to extract proton out of catholyte. Electrolytic voltage at 100 mA cm−2 is as low as 0.88 V; this voltage is only 35% of the voltage used in the traditional electrolysis.