Hydrothermal synthesis of ZnO-Eu2O3 binary oxide with straight strips morphology and sensitivity to NO2 gas

► Hydrothermal synthesis of ZnO-Eu2O3 with straight strips morphology. ► Crystalline framework indexed to wurtzite ZnO and Eu2O3 as secondary phase. ► Surface chemistry revealed the presence only of Eu3+ in Eu2O3. ► At pure red light emission, Eu atoms are stabilized in the 3+ state in Eu2O3. ► High sensor signal to 3 ppm NO2.