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Effect of reaction time and PVP contents on morphologies of hierarchical 3D flower‐like ZnCo 2 O 4 microstructures for energy storage devices
Author(s) -
Gutturu Rajasekhara Reddy,
T. V. M. Sreekanth,
Rajavaram Ramaraghavulu,
Borelli Deva Prasad Raju,
G. R. Dillip,
P. C. Nagajyothi,
J. Shim
Publication year - 2020
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.5719
Subject(s) - x ray photoelectron spectroscopy , polyvinylpyrrolidone , microstructure , chemical engineering , materials science , electrochemistry , specific surface area , stoichiometry , analytical chemistry (journal) , nanotechnology , chemistry , electrode , polymer chemistry , organic chemistry , composite material , catalysis , engineering
Summary Hierarchical 3D flower‐like ZnCo 2 O 4 (ZCO) microstructures assembled from petal‐like nanosheets/flakes of non‐uniform sizes were engineered by a polyvinylpyrrolidone (PVP)‐assisted hydrothermal method. Four different samples/morphologies of ZCO were obtained (PVP‐L@6, PVP‐H@6, PVP‐L@12, and PVP‐H@12) by altering the reaction parameters such as surfactant concentration (PVP) and reaction time, which can play a significant role in the formation of flower‐/petal‐/flake‐like architectures. The alteration of the reaction parameters not only resulted in morphological changes but also affected the surface area, pore size/volume, crystalline nature, non‐stoichiometry of Zn, Co, and O in ZCO, and their electrochemical performance. The metal (Zn/Co)/O deficiencies of ZCO samples were investigated via X‐ray photoelectron spectroscopy and supported by the Rietveld refinement method. Furthermore, a plausible growth mechanism for these flower‐like ZCO microstructures was projected based on the experimental results. The four dissimilar samples/morphologies of ZCO, which exhibit different electrochemical performances, were investigated. Our results show that PVP‐H@12 exhibits higher specific capacitance (761/680 F g −1 at 0.35/1 A g −1 ) and good cycling constancy (90% capacitive retention after 2000 cycles at 5 Ag −1 ) among all the four samples.