Boron-doped graphene quantum dot/Ag–LaFeO3 p–p heterojunctions for sensitive and selective benzene detection

Abstract

Carrier-transport is important in the field of metal oxide semiconductor gas sensors because it directly determines the sensor response and operating temperature. In this paper, gas sensors for monitoring of benzene are developed based on a boron-doped graphene quantum dot (BGQD)/Ag–LaFeO₃ p–p heterojunction (B/APPH). The band gap of the BGQDs and Ag–LaFeO₃ matched well, promoting separation of electron–hole pairs and enhancing the carrier transport ability. The introduced Ag catalytically oxidized benzene into CO₂ and H₂O in gas-sensing reactions. We optimized the selectivity of the B/APPH by benzene molecular imprinting. Our results show that B/APPH possesses a high response (17.5) and good selectivity, repeatability, and accuracy at a low operating temperature (65 °C) for detection of as little as 1 ppm of benzene. The heterojunction between the BGQDs and Ag–LaFeO₃ improved the carrier-transport ability and reduced the operating temperature while maintaining the high sensing response and selectivity. The ability to modulate carrier-transport developed in this work will guide work on high performance gas sensors based on metal oxide semiconductors.