Multinary Tetrahedrite (Cu_12-MNSb₄S₁₃) Nanoparticles: Tailoring Thermal and Optical Properties with Copper-Site...

Tetrahedrite (Cu₁₂Sb₄S₁₃) is an earth-abundant and nontoxic compound with prospective applications in green energy technologies such as thermoelectric waste heat recycling or photovoltaic power generation. A facile, one-pot solution-phase modified polyol method has been developed that produces high-purity nanoscale tetrahedrite products with exceptional stoichiometric and phase control. This modified polyol method is used here to produce phase-pure quaternary and quintenary tetrahedrite nanoparticles doped on the Cu-site with Zn, Fe, Ni, Mn, or Co. This is the first time that Cu-site codoped quintenary tetrahedrite and Mn-doped quaternary tetrahedrite have been produced by a solution-phase method. X-ray diffraction shows phase-pure tetrahedrite, while scanning and transmission electron microscopy show the size and morphology of the nanomaterials. Energy dispersive X-ray spectroscopy confirms nanoparticles have near-stoichiometric elemental compositions. Thermal stability of quintenary codoped tetrahedrite material is analyzed using thermogravimetric analysis, finding that codoping with Mn, Fe, Ni, and Zn increased thermal stability while codoping with cobalt decreased thermal stability. This is the first systematic study of the optical properties of quaternary and quintenary tetrahedrite nanoparticles doped on the Cu-site. Visible-NIR diffuse reflectance spectroscopy reveals that the quaternary and quintenary tetrahedrite nanoparticles have direct optical band gaps ranging from 1.88 to 2.04 eV. Data from thermal and optical characterization support that codoped tetrahedrite nanoparticles are composed of quintenary grains. This research seeks to enhance understanding of the material properties of tetrahedrite, leading to the optimization of sustainable, nontoxic, and high-performance photovoltaic and thermoelectric materials.