Browsing by Author "Gadhamshetty, Venkataramana"
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Item Oxygen Reduction Reaction with Manganese Oxide Nanospheres in Microbial Fuel Cells(American Chemical Society, 2022) Vemuri, Bhuvan; Chilkoor, Govinda; Dhungana, Pramod; Islam, Jamil; Baride, Aravind; Koratkar, Nikhil; Ajayan, Pulickel M.; Rahman, Muhammad M.; Hoefelmeyer, James D.; Gadhamshetty, VenkataramanaOperating microbial fuel cells (MFCs) under extreme pH conditions offers a substantial benefit. Acidic conditions suppress the growth of undesirable methanogens and increase redox potential for oxygen reduction reactions (ORRs), and alkaline conditions increase the electrocatalytic activity. However, operating any fuel cells, including MFCs, is difficult under such extreme pH conditions. Here, we demonstrate a pH-universal ORR ink based on hollow nanospheres of manganese oxide (h-Mn3O4) anchored with multiwalled carbon nanotubes (MWCNTs) on planar and porous forms of carbon electrodes in MFCs (pH = 3–11). Nanospheres of h-Mn3O4 (diameter ∼ 31 nm, shell thickness ∼ 7 nm) on a glassy carbon electrode yielded a highly reproducible ORR activity at pH 3 and 10, based on rotating disk electrode (RDE) tests. A phenomenal ORR performance and long-term stability (∼106 days) of the ink were also observed with four different porous cathodes (carbon cloth, carbon nanofoam paper, reticulated vitreous carbon, and graphite felt) in MFCs. The ink reduced the charge transfer resistance (Rct) to the ORR by 100-fold and 45-fold under the alkaline and acidic conditions, respectively. The current study promotes ORR activity and subsequently the MFC operations under a wide range of pH conditions, including acidic and basic conditions.Item Sustainable valorization of asphaltenes via flash joule heating(AAAS, 2022) Saadi, M.A.S.R.; Advincula, Paul A.; Thakur, Md Shajedul Hoque; Khater, Ali Zein; Saad, Shabab; Shayesteh Zeraati, Ali; Nabil, Shariful Kibria; Zinke, Aasha; Roy, Soumyabrata; Lou, Minghe; Bheemasetti, Sravani N.; Bari, Md Abdullah Al; Zheng, Yiwen; Beckham, Jacob L.; Gadhamshetty, Venkataramana; Vashisth, Aniruddh; Kibria, Md Golam; Tour, James M.; Ajayan, Pulickel M.; Rahman, Muhammad M.The refining process of petroleum crude oil generates asphaltenes, which poses complicated problems during the production of cleaner fuels. Following refining, asphaltenes are typically combusted for reuse as fuel or discarded into tailing ponds and landfills, leading to economic and environmental disruption. Here, we show that low-value asphaltenes can be converted into a high-value carbon allotrope, asphaltene-derived flash graphene (AFG), via the flash joule heating (FJH) process. After successful conversion, we develop nanocomposites by dispersing AFG into a polymer effectively, which have superior mechanical, thermal, and corrosion-resistant properties compared to the bare polymer. In addition, the life cycle and technoeconomic analysis show that the FJH process leads to reduced environmental impact compared to the traditional processing of asphaltene and lower production cost compared to other FJH precursors. Thus, our work suggests an alternative pathway to the existing asphaltene processing that directs toward a higher value stream while sequestering downstream emissions from the processing.