Controllable Cu + /Cu 2+ ratio for the gas-sensing property of (Na, Cu) co-doped ZnO investigated by EPR and SPV

Key Points

• The study aims to investigate how varying the Cu+ / Cu2+ ratio affects the gas-sensing properties of (Na, Cu) co-doped ZnO.
• Examined the effects of sodium doping on copper oxidation states in ZnO sensors.
• Utilized Electron Paramagnetic Resonance (EPR) and Surface Photovoltage (SPV) techniques.
• Focused on room-temperature detection of nitrogen dioxide (NO2).
• Increased Na doping shifts Cu2+ to Cu+, enhancing gas-sensing behavior.
• The sensors can detect NO2 at concentrations as low as 250 parts per billion (ppb).
• More oxygen vacancies were introduced by co-doping, improving sensor performance.