Computational insights into the structural and electronic properties of first-row transition metal-doped In₂O₃...

Indium oxide (In₂O₃) has emerged as a promising catalyst for CO₂-to-methanol conversion, although its efficiency is limited by poor H₂ activation. Inspired by recent findings that economical Co-doping enhances the catalytic performance of In₂O₃, this study employs density functional theory (DFT) to systematically investigate the structural and electronic properties of first-row 3d transition metals (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) doped In₂O₃, aiming to guide rational catalyst design. The present analysis shows that the electronic configuration of the TM dopant plays a critical role in determining its preferred doping site, formation energy, charge transfer, and electronic distribution. Overall, early transition metals (TMs) exhibit lower formation energies and thus higher thermodynamic stability, whereas late TMs involve higher formation energies. A strong linear correlation between formation energy and Bader charge transfer indicates that electron-donating ability is the dominant factor governing doping stability, whereas the correlation with the d-band center is moderate. The analysis of the projected density of states (PDOS) reveals that metals with partially d filled orbitals contribute significantly near the Fermi level, E_F, which may enhance the electron transfer and catalytic activity. In contrast, metals with fully filled d orbitals display negligible contribution. This systematic screening of dopants offers a general strategy to enhance In₂O₃ catalytic performance and provides a theoretical foundation for the rational design of cost-effective catalysts.