Ultra-sensitive H 2 S sensor based on sunflower-like In-doped ZnO with enriched oxygen vacancies.
Yong-Hui ZhangYing-Ying LiXuan-Yu YangFei-Long GongJun-Li ChenKe-Feng XieHao-Li ZhangShao-Ming FangPublished in: Physical chemistry chemical physics : PCCP (2022)
Metal oxide sensors face the challenge of high response and fast recovery at low operating temperatures for the detection of toxic and flammable hydrogen sulfide (H 2 S) gases. Herein, novel In-doped ZnO with a sunflower-like structure and tunable surface properties was rationally synthesized. The substitutional In atom in the ZnO crystal can dramatically enhance the concentration of oxygen vacancies (O v ), the In-ZnO sites are responsible for fast recovery, and the formation of sub-stable sulfide intermediates gives rise to the high response towards H 2 S. As a result, the response of the optimized 4In-ZnO sensor is 3538.36 to 50 ppm H 2 S at a low operating temperature of 110 °C, which is 106 times higher than that of pristine ZnO. Moreover, the response time and recovery time to 50 ppm H 2 S are 100 s and 27 s, respectively, with high selectivity and stability. First-principles calculations revealed that 4In-ZnO with rich O v exhibited higher adsorption energy for the H 2 S molecule than pristine ZnO, resulting in effortless H 2 S detection. Our work lays the foundation for the rational design of highly sensitive gas sensors through precise doping of atoms in oxygen-rich vacancies in semiconductor materials.