Fluorine and oxygen-functionalized silicon nitride with abundant oxygen vacancies for cataluminescence sensing of H2S

Efficient, selective and highly sensitive detection of H2S is important for environmental protection and human security. Nanomaterials-based cataluminescence (CTL) sensors, especially metal-free catalysts, have been used for gas sensing. Herein, due to the efficient electron transfer and high specific area of silicon nitride (Si3N4), combined with the strong electronegativity of fluorine and oxygen, we purposely synthesized F and O-modified Si3N4 (F/O-Si3N4) by engineering surface states and catalytic properties. We then used it to construct a H2S CTL gas sensor. Compared with other metal-based CTL sensors, the F/O-Si3N4-based CTL system exhibited high sensitivity and a longer lifetime stability. The detection limit was 0.027 & mu;g mL-1 in the detection range of 0.49-8.17 & mu;g mL-1, and a relative standard deviation (RSD) of better than 3.3% were obtained. Further research demonstrated the luminescence mechanism, in which the rich oxygen vacancies of Si3N4 promoted the adsorption of O2 and the formation of F-Si sites due to the catalytic oxidation of H2S and the generation of SO2*. This served as the main emitter accounting for the strong CTL emission. This work is the first report of the application of Si3N4 as a catalyst for CTL H2S sensing. This will expand the methods for enhancing the catalytic activity and practical applications of metal-free materials.