MOF-derived spherical NixSy/carbon with B-doping enabling high supercapacitive performance

This work uses a simple Ni-metal organic framework (Ni-MOF) to generate a uniform metal-containing carbon hybrid structure of Ni/C by in-situ pyrolysis. Then, after NaBH4 treatment and hydrothermal vul-canization of Ni/C, multiphase B-doped NixSy nanoparticles can be obtained and uniformly anchored in the carbon skeleton, forming a highly porous flower-shaped B-NixSy/C composite. The positive role of B doping was theoretically confirmed by Density Function Theory (DFT) calculations. The MOF-derived car -bon framework has porous, conductive, and continuous features beneficial for fast charge transfer. There are also multiple Ni-sulfide phases in B-NixSy/C, dominated by hexagonal NiS, hexagonal Ni2S3, and cu-bic Ni3S4, which give rich valance state and are expected to bring active electrochemical reactions. In addition, the boronation process by the reducing agent of NaBH4 is also proved beneficial to bring high capacitance, possibly due to the incorporation of more active sites by B. Therefore, the B-NixSy/C compos-ite electrode delivers a high specific capacity of 1250.4 C g-1 at 1 A g-1 and excellent rate performance. The B-NixSy/C-based asymmetric supercapacitor also shows promising prospects for future energy stor-age devices, delivering high cyclability with capacitance retention of 87.6% after 70 0 0 cycles. This work proves the efficiency of MOF-derived carbon framework and B-doping in improving metal sulfide's elec-trochemical performances.(c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study demonstrates the use of a simple Ni-MOF material to generate a uniform Ni/C metal-carbon hybrid structure through in-situ pyrolysis. The resulting B-NixSy/C composite exhibits high specific capacity and excellent rate performance, making it a promising candidate for energy storage devices. The inclusion of boron and the porous and conductive carbon framework derived from MOF contribute to the enhanced electrochemical performances of metal sulfides.