Ultra-sensitive H2S sensor based on sunflower-like In-doped ZnO with enriched oxygen vacancies

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 (H2S) 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 H2S. As a result, the response of the optimized 4In-ZnO sensor is 3538.36 to 50 ppm H2S at a low operating temperature of 110 degrees C, which is 106 times higher than that of pristine ZnO. Moreover, the response time and recovery time to 50 ppm H2S 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 H2S molecule than pristine ZnO, resulting in effortless H2S 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.

Automated summary

This study successfully synthesized novel In-doped ZnO materials with tunable surface properties and a sunflower-like structure. The In-doping dramatically increased the concentration of oxygen vacancies, leading to fast recovery and high response towards H2S at low temperatures. The optimized 4In-ZnO sensor showed a response of 3538.36 to 50ppm H2S at 110 degrees C, with a response time of 100s and a recovery time of 27s, demonstrating high selectivity and stability. First-principles calculations indicated that 4In-ZnO exhibited higher adsorption energy for H2S, enabling effortless H2S detection.