The electrocatalysis of urea represents an important potential as an efficient technology for sustainable energy development. This anodic reaction generates hydrogen or electrical power through direct electrooxidation of urea molecules, but is greatly inhibited by its slow kinetics. Therefore, tailoring highly efficient, earth‐abundant, and durable electrocatalysts for urea oxidation reaction (UOR) is a fundamental for the enhancement of green energy conversion technologies. Herein, we report a scalable synthetic strategy to construct three‐dimensional (3D) nickel‐cobalt layered double hydroxide nanosheet arrays (NiCo−LDH NSAs) with silver (Ag0) or gold (Au0) and palladium (Pd0) intercalants as high performance catalysts for UOR. Experimental results suggest that the interlayer spacing of multi‐anions LDH NSAs can effectively afford synergetic effects of increased electrochemical surface area, better exposure of catalytically active sites, and favorable adsorption energy of urea molecules. As expected, the deposition of noble metal nanoparticles (NPs) could successfully modulate the electronic structure, delivering a rise to significantly improved UOR activity. Specifically, the Au/NiCo−LDH hybrid exhibits a superior electro‐catalytic performance toward urea electrooxidation with a highest current. These findings offer an effective pathway to prepare potential earth‐abundant electrocatalysts for direct urea fuel cells (DUFCs).

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Transition-metal selenides based materials have recently aroused an increasing consideration in the field of energy reservation and conversion owing to their good electrochemical performance and low synthetic cost. Herein, multi-walled carbon nanotubes supported binary nickel cobalt selenide composite (NiÀ CoÀ Se/CNT) was prepared by a one-pot-hydrothermal method using hydrazine ions that enables the selenium to diffuse and react with the Ni-and Co-cations to form NiÀ CoÀ Se with a stable nanostructure onto the outer walls of the CNT platforms due to the coordination interaction between the metallic cations and surface oxygen-containing group of the conductive scaffolds. The electrochemical performances for urea oxidation reaction (UOR) are accessed in an alkaline medium by cyclic voltammetry (CV), chronopotentiometry (CA), and electrochemical impedancespectroscopy (EIS) tests. The asprepared NiÀ CoÀ Se/CNT hybrid presents an excellent electrocatalytic activity in terms of current density and onset potential due to synergistic effects of tubular CNT scaffolds, additional Co active sites, and electrochemically active NiOOH layer. The CNTs support markedly enhanced the electrocatalytic properties by providing a rapid mass transport for UOR because of their porous network architectures with a robust adhesion to the NiÀ CoÀ Se nanocrystals. Thus, the synthetic methodology synthetic methodology adopted here is entirely effective for constructing various metal selenide compounds in future.

Low temperature hydrazine fuel cells have been advocated as potential energy carriers by virtue of their exceptional power densities and carbon free containing byproducts. However, the large‐scale application of these renewable energy systems has been extremely inhibited by the insufficient performance and high cost of the state‐of‐art platinum (Pt) catalysts. To pursue better activity, electrocatalysts must demonstrate low operating overpotentials and high tolerances to poisoning species, which are critical factors for increasing the energy conversion efficiency. Despite the tremendous progress of Pt‐based catalysts, controlling sluggish kinetics on microscopic surfaces is still a serious issue because the accumulation of reaction product slugs onto surface may impede the liquid fuel transport to catalytic sites, resulting in a low activity. Thus, the development of earth abundant electrocatalysts with an improved activity is unambiguously a principal requirement. In this review, recent trends in the rational design and synthesis of Ni‐based electrocatalysts with various compositions for hydrazine oxidation reaction (HzOR) are summarized. In particular, development of multicomponent compounds and employment of Ni‐based materials for HzOR are demonstrated to be effective approaches from tuning the electrochemical performance of Ni‐based catalyst materials. Moreover, some potential challenges and prospects are deliberated to further advance the improvement of Ni‐based materials for effective HzOR.

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The design of hierarchical electrodes comprising multiple components with a high electrical conductivity and a large specific surface area has been recognized as a feasible strategy to remarkably boost pseudocapacitors. Herein, we delineate hexagonal sheets‐in‐cage shaped nickel–manganese sulfides (Ni‐Mn‐S) with nanosized open spaces for supercapacitor applications to realize faster redox reactions and a lower charge‐transfer resistance with a markedly enhanced specific capacitance. The hybrid was facilely prepared through a two‐step hydrothermal method. Benefiting from the synergistic effect between Ni and Mn active sites with the improvement of both ionic and electric conductivity, the resulting Ni‐Mn‐S hybrid displays a high specific capacitance of 1664 F g−1 at a current density of 1 A g−1 and a capacitance of 785 F g−1 is maintained at a current density of 50 A g−1, revealing an outstanding capacity and rate performance. The asymmetric supercapacitor device assembled with the Ni‐Mn‐S hexagonal sheets‐in‐cage as the positive electrode delivers a maximum energy density of 40.4 Wh kg−1 at a power density of 750 W kg−1. Impressively, the cycling retention of the as‐fabricated device after 10 000 cycles at a current density of 10 A g−1 reaches 85.5 %. Thus, this hybrid with superior capacitive performance holds great potential as an effective charge‐storage material.