Browsing by Author "Jyoti Kashyap"

Now showing 1 - 3 of 3

Advancing Cryogenic Cooling with Self-Modulated YbAgCu4 for Enhanced Thermoelectric Efficiency below Liquid-Nitrogen Temperatures
(American Chemical Society, 2023) Prayas Chandra Patel; Pankaj K. Mishra; Jyoti Kashyap
This report presents a comprehensive study of the thermoelectric performance of self-modulated YbAgCu4 for cryogenic cooling, T < 50 K. Implementing self-modulation-based nanostructuring by spark-plasma-sintering of powdered sintered and as-spun ribbons together, we obtained a high power factor of ∼2.3 × 10-2 W·m-1·K-2. The grain-boundary scattering in the prepared nanostructured samples significantly decreased the thermal conductivity as compared to the earlier reported values in polycrystalline YbAgCu4. In the present work, the peak thermoelectric figure-of-merit ZT of ∼0.32 at ∼43 K was achieved in the modulated sample. Such never before achieved high ZT at this temperature establishes the applicability of present methodology for cryogenic cooling below 77 K, which could further be extended to other heavy-Fermion materials to enhance their thermoelectric performances. © 2023 American Chemical Society.
Cation doped approach for photodegradation of 4-chlorophenol by highly efficient solar active NiS photocatalyst: The case of Cu2+ doping
(Elsevier B.V., 2023) Prayas C. Patel; Pankaj Kumar Mishra; Jyoti Kashyap; Surabhi Awasthi
This study reports an efficient photodegradation of 4-chlorophenol using Cu2+ doped nickel sulfide (NiS) nanoparticles. Our study provides a facile method to synthesize Cu2+ doped NiS nanoparticles by partial polyol method and structurally validates the formation of single phased random-shaped particles. Cu2+ doping in NiS matrix results in a red shift of the absorption band edge, thus lowering the band gap from 3.62 to 2.98 eV and creating electron trapping centers that prevent electron-hole recombination. The presence of such electron trapping centers was attributed to oxygen vacancies which were justified from the appearance of g-signal in electron paramagnetic resonance analysis. Photodegradation study of 4-chlorophenol by Cu2+ doped NiS nanoparticles under ambient solar light showed significant improvement in degradation efficiency up to 90 % as compared to 19 % for undoped NiS nanoparticles. Furthermore, increased degradation efficiency was also backed by total organic carbon (TOC) analysis of the mineralization ability of Cu2+ doped NiS nanoparticles. Moreover, scavenging trapping analysis showed holes, ⋅OH and superoxide radicals as reactive oxidative species (ROS) primarily responsible for increased photodegradation efficiency. Thus, the synthesized Cu doped NiS nanoparticles proved to be an efficient catalyst, which could be used as a potential candidate for industrial photocatalytic applications under ambient solar light. © 2022 Elsevier B.V.
Fe-As Intermetallic Alloys: A Way Out for Sodium-Ion Batteries
(American Chemical Society, 2023) Prayas Chandra Patel; Surabhi Awasthi; Pankaj Kumar Mishra; Priyanka Lakharwal; Jyoti Kashyap
Intermetallic alloy anodes with high theoretical sodiation capacities are highly sought for next-generation sodium-ion batteries (SIBs). Here, we demonstrate the fabrication of a high-performance intermetallic Fe-As alloy anode for high capacity sodium-ion batteries (SIBs) via a high-throughput and industrially viable melt-spinning process. This earth-abundant low-cost alloy anode exhibits highly enhanced cycling stability, retaining 96% of its 965 mAh·g-1 sodiation capacity after 400 cycles at 50 mA g-1 specific current for SIBs. The exceptional electrochemical performance of the prepared alloy anode is attributed to the crystalline features of the melt-spun fibers, which also enable a remarkable rate performance with ∼668 mAh g-1 sodiation capacity at 5 A g-1. We further demonstrated the application of the prepared alloy anode in a sodium-ion full-cell configuration, where it delivered a sodiation capacity of over 770 mAh g-1 (based on anode) at 50 mA g-1, achieving more than 97% Coulombic efficiency even after 200 cycles. Our results suggest that melt-spun alloy anodes hold great potential for realizing fully functional SIBs. © 2023 American Chemical Society.