Alkali-water electrolyzers and hydroxide exchange membrane fuel cells are emerging as promising technologies to realize hydrogen economy. Developing cost-effective electrode materials with high activities towards corresponding hydrogen evolution (HER) and oxidation (HOR) reactions plays a crucial role in commercial hydrogen production and utilization. Herein, we fabricated a V-doped Ni3N/Ni heterostructure (V-Ni3N/Ni) through a controlled nitridation treatment on a V-incorporated nickel hydroxide precursor. The resultant catalyst exhibits comparable catalytic activity and durability to commercial Pt/C in terms of both HER (a low overpotential of 44 mV at the current density of 10 mA·cm-2) and HOR (a high current density of 1.54 mA·cm-2 at 0.1 V versus reversible hydrogen electrode) under alkaline conditions. The superior activity of V-Ni3N/Ni grown on different substrates further implies its intrinsic performance. Density functional theory (DFT) calculations reveal that the coupled metallic Ni and doped V can promote the water adsorption, accelerate the Volmer step of alkaline HER, as well as optimize the adsorption and desorption of hydrogen intermediate (H*) to reach a balanced ΔGH* value.
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The high energy density of lithium-sulfur batteries (LSBs) is mainly based on the complex redox reactions and phase conversions. The sluggish redox kinetics and the large accumulation of soluble polysulfides in the electrolyte leads to low sulfur utilization and serious shuttle effect. Herein, an integrated sulfur cathode is constructed through a facile and large-scale method. It is composed of sulfur-N, S doped bamboo like CNTs@Co3S4 (NSC@Co3S4) composites on polypropylene separator. The immobilized polysulfides on the NSC@Co3S4 surface are further reduced/oxidized during the discharge/charge process via the efficient bi-functional catalytic effect of NSC@Co3S4, resulting in the rapid conversion of LiPSs. Consequently, the integrated sulfur cathode delivers a high initial reversible capacity of 1, 473.6 mAh·g-1 at 0.2 C and a high specific capacity of 979 mAh·g-1 at 1 C after 500 cycles as well as excellent cycling stability for 1, 000 cycles with a high specific capacity of 362.5 mAh·g-1 at 5 C, which are superior to reported similar host materials.