Realizing golden ultraviolet C emission of 265 nm by oxygen vacancies engineering for 100 % sterilization efficiency

Ultraviolet C (UVC) light has a great promising application in the field of sterilization. However, how to obtain efficient UVC emission with peak maximum at 265 nm that is called ‘golden sterilization wavelength’ remains a great challenge. Herein, we propose a defect-engineering strategy to obtain enhanced UVC emission at the golden sterilization wavelength of 265 nm through introducing oxygen vacancies into Pr³⁺ doped Ba₂MgSi₂O₇ melilite phosphors. Combined with X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) and thermoluminescence (TL) characterizations, it is confirmed that the calcination of Ba₂MgSi₂O₇:Pr³⁺ in an inert atmosphere could efficiently increase oxygen vacancy concentration, promoting the efficient energy transfer from the melilite host to Pr³⁺ ions. It could lead to a significant enhancement of the luminescence intensity to 2.43 times of the initial one with less oxygen vacancies. The optimized Ba₂MgSi₂O₇:0.4%Pr³⁺ phosphor could effectively inactivate 100 % of Staphylococcus aureus within 8 min, showing higher efficiency than commercially available mercury lamp. This work provides an effective solution for the design and preparation of UVC phosphors using defect engineering to achieve golden UVC emission.