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Cobalt phosphide (CoP) is considered to be a potential candidate in the field of electrocatalysis due to its low-cost, abundant resources and high electrochemical stability. However, there is a great space for further improvement of its electrocatalytic performance since its charge transfer rate and catalytic activity have not reached a satisfactory level. Herein, we design and fabricate a three dimensional urchins like V-doped CoP with different amounts of V-doping on nickel foam electrode. The V-doped CoP/NF electrode with optimized amounts of V-doping (10%) exhibits outstanding hydrogen evolution reaction (HER) performance under universal-pH conditions and preeminent oxygen evolution reaction (OER) performance in alkaline media. Notably, the assembled water-splitting cell displays a cell voltage of only 1.53 V at 10 mA·cm−2 and has excellent durability, much better than many reported related bifunctional catalysts. The experiment results and theoretical analysis revealed that vanadium atoms replace cobalt atoms in CoP lattice. Vanadium doping can not only raise the density of electronic states near the Fermi level enhancing the conductivity of the catalyst, but can also optimize the free energy of hydrogen and oxygen-containing intermediates adsorption over CoP, thus promoting its catalytic activity. Moreover, the unique nanostructure of the catalyst provides the various shortened channels for charge transfer and reactant/electrolyte diffusion, which accelerates the electrocatalytic process. Also, the in situ growth strategy can improve the conductivity and stability of the catalyst. [ABSTRACT FROM AUTHOR]

The intelligent construction of electrode nanostructures with unique morphologies is of admirable importance for increasing the energy storage capacity of highly efficient supercapacitor devices. In this study, the negative electrode material Bi2O3/Bi2Se3 nanoflower (Bi2O3/Bi2Se3 NFs) hybrid was first fabricated via a simple one-step solvothermal approach; due to the favorable conductivity of Bi2Se3, high theoretical capacity of Bi2O3 and their distinctive nanostructures, the achieved Bi2O3/Bi2Se3 NFs exhibited the maximum specific capacity of 132.7 mA h g−1 (∼531 F g−1) at 1 A g−1 and the superior rate capability of 113.8 mA h g−1 (∼455 F g−1) at 10 A g−1. Moreover, the positive electrode material NiCoSe2/Ni0.85Se nanoparticles (NiCoSe2/Ni0.85Se NPs) obtained by an electrodeposition method delivered the high specific capacity of 248.4 mA h g−1 (∼1788 F g−1) at 1 A g−1 as well as the appealing rate property of ∼84% capacity retention when the current density was increased by 100 times (i.e., 100 A g−1). More significantly, it was found that the assembled Bi2O3/Bi2Se3 NFs//NiCoSe2/Ni0.85Se NP asymmetric aqueous battery (AAB) device achieved the extraordinary energy density of 88.4 W h kg−1 at the power density of 2.4 kW kg−1 along with a durable lifespan (maintaining the capacity retention of up to 91.5% even after 10 000 cycles). Consequently, the design strategy and novel perspectives reported herein not only hold extensive promise for expanding the preparation techniques of morphology-controlled composites with robust electrochemical properties but also promote the practical applications of newly emerging metal selenides in next-generation aqueous batteries. [ABSTRACT FROM AUTHOR]