Metal monovacancy-induced spin polarization for simultaneous energy recovery and wastewater purification

Construction of metal monovacancies in ZnO reduced eg occupation and induced electron spin polarization near the Fermi level. Moreover, spin-polarized orbital coupling and internal polarization electric field promoted surface redox reactions and accelerated carrier interfacial transfer, which released the restrictions of reaction condition in simultaneously photocatalytic hydrogen generation and pollutant degradation. [Display omitted] •Metal monovacancies are successfully developed in lamellar Zn-V-20.•Low eg occupancy optimizes electron configuration and spin structure.•Simultaneous hydrogen generation and pollutants degradation are enhanced.•Spin polarization proved by DFT and XAS is the reason of photocatalytic enhancement. Simultaneous hydrogen generation and pollutants removal is considered as the potential solution to the energy and environmental crisis, which can cut the consumption of expensive sacrificial electron donors and reduce the ecotoxicity of wastewater containing pollutants. However, the integration of two redox half-reactions in one system is still a challenge, limited by irreconcilable reaction conditions and low kinetics. In this study, ZnO with abundant metal monovacancies (Zn-V-m) was fabricated to manipulate the spin state by tailoring the electron occupancy of eg-orbitals, which simultaneously endowed the material with both outstanding photocatalytic oxidation and reduction performance. Compared with pristine ZnO, the prepared Zn-V-20 increases the H2 production rate by 56.4-fold and enhances the pollutants removal efficiency by 27.5-fold. It is impressive that simultaneous hydrogen generation and pollutants degradation in one system is accomplished and accelerated. Furthermore, Zn L-edge X-ray absorption spectra (XAS) and density functional theory (DFT) calculations suggest that low electron occupancy of eg-orbitals optimizes the spin structure and leads to spin polarization, which provides the critical motivation for enhancing photocatalytic performance. This work accelerates the reaction rates of pollutants degradation and hydrogen generation at the surface interface by manipulating electron spin polarization, guiding the rational design of TMO-based catalysts for simultaneous energy recovery and wastewater purification.