Na+-doping induced synergistic oxygen vacancies and compressive strain for enhanced photocatalytic formaldehyde mineralization

Na + doping in ZnWO 4 simultaneously introduces oxygen vacancies and compressive lattice strain. • The synergy injects electrons into W 5d orbitals, shifting the d-band center upward by 0.29 eV. • This optimized electronic structure enhances the adsorption and activation of both O 2 and HCHO. • The energy barrier for the rate-limiting formate oxidation step is significantly reduced. The efficiency of photocatalytic formaldehyde (HCHO) mineralization is often limited by insufficient adsorption and activation of O 2 and HCHO on conventional semiconductor surfaces. In this work, we demonstrate a ‘kill two birds with one stone’ strategy—Na + doping in ZnWO 4 —which simultaneously introduces oxygen vacancies and compressive lattice strain. This synergistic defect and strain engineering injects electrons into the W 5d orbitals, creating electron-rich W sites and shifting the d-band center upward. The resulting electronic structure enhances the adsorption and activation of both O 2 and HCHO, with adsorption energies reaching −2.08 eV and − 1.02 eV, respectively, significantly reducing the energy barrier of the rate-limiting formate oxidation step from −0.26 eV to −1.45 eV. Consequently, Na-ZnWO 4 achieves markedly improved reactive oxygen species generation, an 80.2% HCHO removal efficiency, and a high CO 2 yield under simulated solar light, greatly outperforming pristine ZnWO 4 . This work demonstrates a co-regulation strategy for defects and strain via cation doping as an effective route toward high-performance photocatalytic materials. Download: Download high-res image (157KB) Download: Download full-size image