Optimizing the <i>n</i>-type carrier concentration of an <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>InVO</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:math> photocatalyst by codoping wit

Although indium vanadate (${\mathrm{InVO}}_{4}$) is an excellent n-type semiconductor, a controlled n-type carrier concentration of the ${\mathrm{InVO}}_{4}$ photocatalyst is required to enhance its photocatalytic activity. This study systematically explores the self-consistent Fermi energies, dominant intrinsic defects, electron concentration (${n}_{0}$), and defect concentration of ${\mathrm{InVO}}_{4}$ using density-functional theory coupled with detailed thermodynamic equilibrium simulations. The results indicate that the ${\mathrm{V}}_{\mathrm{In}}$ antisite defect (the vanadium atom replacing the indium atom) is the dominant intrinsic defect in ${\mathrm{InVO}}_{4}$. The calculated Fermi energy pinning position indicates that ${\mathrm{InVO}}_{4}$ has n-type doping behavior from intrinsic defects under $\mathrm{O}$-poor growth conditions, consistent with the experiments. Interestingly, donor (${D}^{+}$) doping is positive for improving the ${n}_{0}$ of the intrinsic-defect-doped ${\mathrm{InVO}}_{4}$. Therefore, at 300 K, a broad optimized chemical potential region (OCPR) is obtained for ${\mathrm{InVO}}_{4}$ codoped with donors and intrinsic defects. In this OCPR, the ${n}_{0}$ is higher, without recombination centers and significant compensation, significantly enhancing the photocatalytic activity of ${\mathrm{InVO}}_{4}$. However, for the case of growth temperature at 873 K and after quenching from 873 to 300 K, the OCPR is much narrower than that at 300 K, indicating that higher temperatures may adversely affect the OCPR. Our results provide deep insights into defect behaviors in ${\mathrm{InVO}}_{4}$ and suggest strategies for enhancing its n-type conductivity properties, offering new opportunities for manipulating the photocatalytic performance of ${\mathrm{InVO}}_{4}$.