Exploring Antimony-Based Nanostructured Hybrids for Alkali Metal-Ion Batteries Anode and Visible-Light-Driven Photocatalytic Dye Degradation

Abstract

Over the last few decades, energy and environmental problems have increased manifolds owing to various socio-economic reasons. However, an uninterrupted supply of electricity is essential for modern lifestyles due to a surge in demand for electronic gadgets and the emergence of hybrid electric vehicles in the 21st century. In this regard, alkali metal-ion batteries viz. rechargeable Li-ion batteries (LIBs) are still considered the ‘holy grail’ for energy storage applications, starting from portable electronics to EVs. However, the exorbitant cost of lithium compounds and the dilapidated global reserve is a severe threat to the future of LIBs. In the recent past, conceptually similar sodium-ion batteries (SIBs) have been proposed as a low-cost alternative to the existing LIBs in view of the abundance and wide distribution of the sodium-bearing compounds on earth. However, it is crucial to develop high-capacity anodes for practical deployment and realization of SIBs to reach their full potential. In addition, the globalization of textile industries has witnessed adverse effects on the environment due to water pollution from effluent waste-water containing hazardous organic toxic dye. The treatment of toxic organic effluents is highly desirable for the preservation of clean water. Therefore, it is paramount to develop low-cost, visible-light-driven photocatalysts to degrade these toxic pollutants. The present work tries to make an attempt to identify and explore Sb-based materials as a potential solution to the global energy storage and water pollution problem mentioned above by designing and developing Sb/C hybrid LIBs/SIBs anodes and Sb2S3 based compounds for visible-light-driven photocatalyst. Among various materials explored to date, nanostructured antimony-based (Sb) hybrid compounds are considered a promising anode for LIBs/SIBs and solar-light-driven photocatalyst towards dye degradation owing to its attractive electrical and electronic properties. However, Sb-based materials suffer from poor electrochemical performance and photocatalytic activity due to large volumetric variance during (de)alloying with Li/Na and fast recombination rate of photogenerated electron-hole pairs, respectively. Sb-based anodes have two major disadvantages includes significant volume swelling (~135%-293%) and detachment of active phase from the current collector upon (de)alloying with Li and Na. One way to improve the electrochemical performance in LIB/SIBs and photocatalytic activity of Sb/Sb2S3 based materials is hybridizing with carbon and analog and developing myriads of nanostructured compounds. Carbonaceous materials viz. reduced graphene oxide (rGO) and resorcinol-formaldehyde (RF) derived porous carbon are particularly attractive for Sb-based carbonaceous composite formulation for LIBs/SIBs anodes and photocatalytic degradation of industrial dyes. In the present work, Sb-based nanostructured (SbNPs, Sb/rGO, core-shell Sb@C, yolk-shell Sb@void@C, Sb2S3 nanorods, Sb2S3/rGO, Sb2S3-NPs, core-shell Sb2S3@C, Sb2S3-NPs/rGO, and Bi1.09Sb0.91S3/rGO) anodes have been successfully synthesized via facile hydrothermal and sol-gel routes. In addition, Sb2S3 nanorods, Sb2S3 nanorods/rGO, Sb2S3-NPs, Sb2S3-NPs/rGO, Sb2S3-NPs@C, and BixSb2-xS3 [x = 0.536, 1.09, 1.68] narrow bandgap photocatalysts have been explored for photocatalytic degradation of Rhodamine-B (RhB) dye. Various analytical tools viz. XRD, FTIR, TG, Raman spectroscopy, FESEM, TEM, XPS, and BET surface area analysis were utilized to determine phase, structure, morphology, valence, and specific surface area of as-synthesized Sb-based nanostructured hybrid. The effect of varying rGO content, the role of porous carbon coating on the stable electrochemical performance of Sb-based anodes were investigated in detail using LIBs and SIBs half-cell and full-cell. The electrochemical results show that carefully chosen optimal amount of rGO and ultrathin porous carbon improves electrochemical performance due to fast charge-transfer, minimum solid electrolyte interphase (SEI) resistance across electrode/electrolyte interphase, validated by EIS, Li+/Na+ diffusion coefficient, ex-situ FESEM, XRD, and XANES analysis of the cycled electrodes. In addition, binder-free electrodes fabricated by electrophoretic deposition (EPD) in quick time (~3 min) showed stable electrochemical performance compare to the conventional doctor blade technique offering a useful strategy for preventing Sb delamination. The dissertation work successfully demonstrates that Sb-based SIBs anodes would be suitable candidates for future energy storage needs, and narrow band gap Sb2S3 and BixSb2-xS3-based photocatalysts exhibiting excellent photocatalytic activity would be potentially suitable for waste-water treatments.