Application of MXene-Based Molecular Sieves in Improving Selectivity of Semiconductor Hydrogen Sensors

The poor gas selectivity of semiconductor resistive gas sensors has been limiting their practical applications. Since semiconductor sensor devices are in direct contact with gases, filtering the gases during gas transmission to isolate the interfering gases and prevent the sensor devices from meeting them is an effective method to improve the selectivity of the sensors. In this article, a molecular sieve film is reported for semiconductor sensor filters, which can substantially isolate other interfering gases except hydrogen and still retain a high throughput rate for hydrogen. The molecular sieve film is synthesized from the 2-D material MXene, which has strong adhesion and flexibility properties, and can be perfectly integrated with the metal filters, which greatly improves the value of the molecular sieve film for practical applications. After systematic testing, it is found that the sensor equipped with molecular sieve compared to no molecular sieve sensor for methane, ammonia, and carbon monoxide has about 90% reduction in sensitivity, exciting is still retained 91% of the sensitivity of hydrogen, which is due to the molecular sieve membrane in the nanoscale pores (0.35 nm) in the molecular sieve membrane, which selectively isolates large molecular gases other than hydrogen. This work provides a new approach to improve the selectivity of semiconductor-based hydrogen sensors.