Na Zhao,Jian Qin,Lujia Chu,Linzhe Wang,Dan Xu,Xiujuan Wang,Huijuan Yang,Jiujun Zhang,XiFei Li
The development of potassium ion batteries is restricted by the intrinsic large ion radius, resulting in dramatic volume change of electrodes and slow faradic reaction in kinetics. High requirements are proposed for the structure design of anodes. In this work, Se coating-Sb nanocrystalls-three dimensional interconnected carbon networks (3D Se@Sb@C) heterogeneous structure was prepared by a low-temperature template-assisted CVD method. The network and sandwich structure can not only shorten the solid-state diffusion path of K + , but also alleviate the volume change of Sb. Moreover, the hetero interface between Se and Sb can form chemical bonding and further generate heterogeneous junctions in electrochemical reactions, providing more electron states at the Fermi energy level and reducing the ionic diffusion barrier of K + . Benefiting from it, the 3D Se@Sb@C electrode possess an optimized energy storage mechanism and exhibits an outstanding rate performance and an ultra-long lifespan of more than 5000 cycles with 87% of capacity retention, which is rarely reported for PIB anodes. It reveals the important role of heterogeneous structure in potassium storage, which can inspire other researchers to achieve superior electrochemical performance by interface engineering for electrode materials.
In the quest to replace fossil fuels and reduce carbon dioxide emissions, developing energy technologies based on clean catalytic processes is fundamental. However, the cost-effectiveness of these technologies strongly relies on the availability of efficient catalysts made of abundant elements. Herein, this study presents a one-step hydrothermal method to obtain a series of Ni3Se4 nanoparticles with a layer of amorphous selenium on their surface. When employed as electrocatalysts for the methanol oxidation reaction (MOR), the optimized proper surface Se-coated Ni3Se4 nanoparticles exhibit a high current density of 160 mA cm–2 at 1.6 V, achieving a high methanol-to-formate Faradaic efficiency above 97.8% and excellent stability with less than 20% current decay after an 18 h chronoamperometry test. This excellent performance is rationalized using density functional theory calculations, which unveil that the electrochemical recombination of SeOx results in a reduction of the energy barrier for the dehydrogenation of methanol during the MOR process.
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