Waste Citrus reticulata Assisted Preparation of Cobalt Oxide Nanoparticles for Supercapacitors

Rishabh Srivastava; Shiva Bhardwaj; Anuj Kumar; Rahul Singhal; Jules Scanley; Christine C Broadbridge; Ram K Gupta

doi:10.3390/nano12234119

Waste Citrus reticulata Assisted Preparation of Cobalt Oxide Nanoparticles for Supercapacitors

Nanomaterials (Basel). 2022 Nov 22;12(23):4119. doi: 10.3390/nano12234119.

Authors

Rishabh Srivastava^{1

2}, Shiva Bhardwaj^{1

2}, Anuj Kumar³, Rahul Singhal⁴, Jules Scanley⁵, Christine C Broadbridge⁵, Ram K Gupta^{2

6}

Affiliations

¹ Department of Physics, Pittsburg State University, Pittsburg, KS 66762, USA.
² National Institute of Material Advancement, Pittsburg, KS 66762, USA.
³ Nano-Technology Research Laboratory, Department of Chemistry, GLA University, Mathura 281406, Uttar Pradesh, India.
⁴ Department of Physics and Engineering Physics, Central Connecticut State University, New Britain, CT 06050, USA.
⁵ Connecticut State Colleges and Universities (CSCU) Center for Nanotechnology, Southern Connecticut State University, New Haven, CT 06515, USA.
⁶ Department of Chemistry, Pittsburg State University, Pittsburg, KS 66762, USA.

Abstract

The green, sustainable, and inexpensive creation of novel materials, primarily nanoparticles, with effective energy-storing properties, is key to addressing both the rising demand for energy storage and the mounting environmental concerns throughout the world. Here, an orange peel extract is used to make cobalt oxide nanoparticles from cobalt nitrate hexahydrate. The orange peel extract has Citrus reticulata, which is a key biological component that acts as a ligand and a reducing agent during the formation of nanoparticles. Additionally, the same nanoparticles were also obtained from various precursors for phase and electrochemical behavior comparisons. The prepared Co-nanoparticles were also sulfurized and phosphorized to enhance the electrochemical properties. The synthesized samples were characterized using scanning electron microscopic and X-ray diffraction techniques. The cobalt oxide nanoparticle showed a specific capacitance of 90 F/g at 1 A/g, whereas the cobalt sulfide and phosphide samples delivered an improved specific capacitance of 98 F/g and 185 F/g at 1 A/g. The phosphide-based nanoparticles offer more than 85% capacitance retention after 5000 cycles. This study offers a green strategy to prepare nanostructured materials for energy applications.

Keywords: Citrus reticulata; Co3O4 nanoparticles; characterization; charge storage; supercapacitors.

Grants and funding

Authors are grateful to the National Institute of Standards and Technology (NIST award number 70NANB20D146) and the U.S. Economic Development Administration (US-EDA award number 05-79-06038) for providing research infrastructure.