As a semiconductor photocatalyst, antiferromagnetic (AFM) CuWO4 exhibits a weak n-type behavior in experiments, yet the microscopic origins and effective strategies for enhancing its electron concentration (n0) remain unclear. This study systematically analyzes the self-consistent Fermi level, n0, and dominant intrinsic defect concentrations in CuWO4 by using spin-polarized density functional theory and thermodynamic equilibrium simulations. The calculated formation energies indicate that Cu interstitials (Cui2+), O vacancies (VO42+), and Cu vacancies (VCu2-) are the dominant intrinsic defects in CuWO4 across relevant chemical potential ranges; however, the low Cui2+ and VO42+ concentrations and compensation by VCu2- result in intrinsically weak n-type conductivity. Moreover, donor (D+) and intrinsic defect codoping enhances n0 only within a narrow optimized chemical potential region (OCPR) under Cu-rich/W-rich/O-poor conditions at 300 K, where the compensation between VCu2- and D+ is suppressed. Remarkably, quenching from 800 to 300 K obviously broadens the OCPR by significantly reducing the VCu2- concentration, enabling higher room-temperature n0 in CuWO4 with negligible charge compensation and recombination effects. Thus, this study identifies the origins and fundamental bottleneck of weak intrinsic n-type CuWO4 and provides an experimentally accessible route to obtain higher n-type conductivity in CuWO4, which could significantly enhance its photocatalytic performance.
Song et al. (Tue,) studied this question.