Vanadium-Engineered Co2NiSe4 Nanomaterial: Coupled Thermoelectric, Piezoelectric, and Electronic Optimization via DFT+U for Advanced Energy Applications

Abstract: To realize the creation of advanced multifunctional materials in energy storage and conversion technologies, the present research evaluates the structural, electronic, magnetic, thermodynamic, mechanical, thermoelectric, piezoelectric and optical properties of pristine and vanadium-doped Co2NiSe4 by first-principles density functional theory (DFT + U ). It addresses the use of vanadium substitution to tailor the material, its performance and the inclusion of diverse fields by changing its electronic structure and its bonding properties. It can be seen in the results that V doping improves electrical conductivity and magnetic ordering because of a higher density of states and a stronger spin polarization at the Fermi level. Thermodynamic calculations show enhanced entropy stabilization at high temperatures and, mechanical analysis suggests an enhanced elastic moduli that proves the enhanced structural integrity without affecting ductility. The thermoelectric properties have been greatly improved realize an optimal ZT of ~1.1 at 900 K with 5 at.% V doping owing to an ideal combination of Seebeck coefficient, electrical conductivity, and inhibited thermal conductivity. Also, optical analysis reveals that expanded absorption spectra, increased dielectric response, adjustable reflectivity and energy loss spectra, optical properties can be used in photonic, and other optoelectronic devices. Better piezoelectric coefficients due to its effectiveness when doped also appeal to the usefulness of its application in nanoscale electromechanical systems. The combination of these results makes V-doped Co2NiSe4, a versatile material platform of next-generation energy storage, thermoelectric generation, and novel multifunctional sensors.