RESEARCH ARTICLE Nanoporous hierarchical carbon structures derived from fungal basidiocarps for high performance supercapacitors Krishna Prasad Gannavarapu 1 | Samar Azizighannad 2 | Muralikrishna Molli 3 | Meera Pandey 4 | Sai Muthukumar V 3 | Somenath Mitra 2 | Rajesh Babu Dandamudi 1 1 Department of Chemistry, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam Campus Puttaparthi, Anantapur District, Andhra Pradesh, India 2 Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 3 Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam Campus Puttaparthi, Anantapur District, Andhra Pradesh, India 4 Department of Plant Pathology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore, Karnataka, India Correspondence Rajesh B. Dandamudi, Department of Chemistry, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam Campus Puttaparthi, Anantapur District, Andhra Pradesh 515134, India. Email: drajeshbabu@sssihl.edu.in Somenath Mitra, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, 151 Tiernan Hall, Newark, NJ 07102. Email: somenath.mitra@njit.edu Funding information Department of Science and Technology, Ministry of Science and Technology, Grant/ Award Number: SR/FST/PSI-172/2012; National Institute of Environmental Health Sciences, Grant/Award Number: R01ES023209 Abstract This article presents the first report on systematic synthesis and evaluation of acti- vated carbons from the cap and stalk of two diverse mushroom species namely, Ganoderma lucidum (GL) and Calocybe indica (CI) belonging to different classes white rot and brown rot respectively. A novel microwave induced H 3 PO 4 activation followed by carbonization and KOH activation enabled the formation of activated carbon with hierarchical structures. The activated carbons from cap and the stalk of the mushrooms are different in terms of specific surface area, pore volume, and their electrochemical behavior. Specific surface area and pore volume from GL-cap is as high as 2432.4 m 2 /g and 0.54 CC/g, respectively. After optimization, the acti- vated carbons have high graphitic content, good thermal stability and show specific capacitance as high as 271.94 F/g, energy and power densities of 13.59 Wh/kg and 127.31 W/kg, respectively. All the carbons show good capacitance retention up to 10 000 cycles. The surface area and specific capacitance in the mushroom stalks are lower than the ones made from the caps and the highest surface area and specific capacitance are 1576.2 m 2 /g and 137.2 F/g respectively for GL-stalk. KEYWORDS activated carbon, Calocybe indica, Ganoderma lucidum, hierarchical porous structures, mushrooms, super capacitance 1 | INTRODUCTION The physical and chemical properties of activated carbon (AC) such as porosity, surface area, and surface chemistry are important considerations for different applications. 1 Com- mercially available ACs are traditionally made from synthetic polymers to achieve hierarchical structuring 2 or from plant materials like coconut shell. 3 These have been used as sorbents for heavy metals 4 and dyes, 5 as capacitor electrodes, 6 and as solid supports for catalysts. 7 The precursor as well as the physical/chemical processes in synthesis and activation steps play major roles in determining the characteristics and proper- ties of the resulting AC, which can be microporous, meso- porous, or macroporous. 8 ACs have been traditionally derived from high temperature carbonization of both natural and synthetic polymers. 9 Among Received: 5 April 2019 Revised: 29 April 2019 Accepted: 29 April 2019 DOI: 10.1002/est2.58 Energy Storage. 2019;1:e58. wileyonlinelibrary.com/journal/est2 © 2019 John Wiley & Sons, Ltd. 1 of 12 https://doi.org/10.1002/est2.58