The Dynamic Bandgap Evolution Mechanism of Nanophase ZrO ₂ With Synergistic Bandgap Narrowing Strategy

Enhancing the light‐absorption ability of ZrO 2 by reducing the bandgap is important for the development of high performance solar‐driven catalyst. This study systematically investigates the effects of Ce doping and thermal reduction on the bandgap of ZrO 2 by experiments and density functional theory (DFT) calculations. The results demonstrate that both Ce doping and thermal reduction facilitate the formation of oxygen vacancies (O V ) through distinct mechanisms, ultimately leading to the bandgap reduction of ZrO 2 . As X‐ray diffraction, transmission electron microscopy, X‐ray photoelectron spectroscopy (XPS), Raman, and electron paramagnetic resonance revealed, Ce doping can induce the cell distortion of ZrO 2 . Zr3Ce1p exhibits the largest crystal structure transition, indicating that the low percentage of doped Ce can exert the greatest influence on the ZrO 2 cell structure. Furthermore, thermal reduction can strongly affect the surface of samples and directly raise the O V concentration. As UV–vis spectra revealed, the synergistic strategy can minimize the bandgap of ZrO 2 (5.03 eV) to 1.87 eV (Zr3Ce1Ca2), showing a 62.8% decrement. Meanwhile, Zr3Ce1Ca2 shows the fastest degradation of methylene blue (24.73%) under light conditions without a sacrificial agent, higher than ZrO 2 by 242%. The valence band‐XPS spectra and DFT results demonstrated that the downward extension of the conduction band bottom is the main reason for the bandgap shortening.