Min Wang,Kaisheng Chen,Guanjun Sun,Zihao Yan,Yongjun Chen,Hongtao Liu,Erling Zhao,Jianbao Li,Xiwen Du
The development of efficient electrocatalysts for hydrogen evolution reaction (HER) in neutral media remains a challenge due to their slow kinetics and low conductivity. Metal selenides are widely used as HER catalysts, but their structural stabilities are not good and the HER performances in neutral media need to be improved. Herein, we report the direct growth of Mo-doped CuSe (Mo 0.33 Cu 0.67 Se) nanosheets with edge-amorphization on Ni foam (NF) through a facile one-pot solvothermal method for the first time, which are inexpensive and possess high-HER performances in neutral media. It was found that Mo 0.33 Cu 0.67 Se only requires an overvoltage of 55 mV to reach a current density of 10 mA cm −2 (with a Tafel slope of 75 mV dec -1 ), which is superior to commercial 20 % Pt/C (73 mV). Doping CuSe with Mo could lead to amorphization of the edges of nanosheets, and both experimental and theoretical results verify that this structure is beneficial for reducing the oxidative dissolution of Se ion and improving stability. Meanwhile, it also optimizes the free energy of H 2 O dissociation, hydrogen adsorption and desorption, thereby effectively enhancing the performance of electrocatalytic hydrogen evolution in neutral media.
Chen Chen,Qilin Hu,Fan Yang,Hongyu Xue,Yuning Zhang,Hailong Yan,Yang Lu,Yongsong Luo
Due to the low price and abundant reserves of sodium resources, sodium-ion batteries have become the main candidate for the next generation of energy storage equipment, particularly for large-scale grid storage and low-speed electric vehicles. Transition metal selenides have attracted considerable attention because of their high reversible capacity, superior electrical conductivity and versatile structures. In this study, two-dimensional CuSe nanosheets are synthesized via a simple hydrothermal reaction. When acting as an electrode material for sodium-ion batteries, the CuSe electrode exhibits an initial coulombic efficiency of 96.7% at a current density of 0.1 A g−1 and a specific capacity of 330 mA h g−1 after 100 operation cycles, as well as retains a specific capacity of 211 mA h g−1 even at a high current density of 10 A g−1. Moreover, the anode delivers a specific capacity of 236 mA h g−1 after 3300 cycles at 5 A g−1 with a capacity retention of 91.2%. In sodium-ion hybrid capacitors (SHICs) with the two-dimensional CuSe nanosheets and Ti3C2Tx MXene as the negative and positive materials, respectively, the nanosheets without any pre-sodiation present a lifespan of up to 2000 cycles at 2 A g−1 and a capacity retention of about 77.7%.
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