Heterointerface Engineering of Porous BiVO4/g-C3N4 Composite for Highly Sensitive Low-Temperature Acetone Detection

The development of highly sensitive and selective acetone sensors is essential for non-invasive disease diagnosis and health monitoring through breath analysis. In this work, a porous BiVO4/g-C3N4 (BVO/g-CN) heterostructure was prepared by first forming porous monoclinic BVO through hydrothermal nucleation and self-assembly of primary crystallites and then anchoring these particles onto thermally polymerized, g-CN nanosheets. The interparticle voids within the BVO aggregates and intersheet galleries of g-CN generated at the BVO/g-CN interface collectively produced the mesoporous architecture. The acetone sensing performance of pristine BVO and BVO/g-CN composites with different g-CN loading amounts was systematically investigated. The optimized BVO/g-CN-2 composite exhibited a BET surface area of 36.6 m2 g–1, compared with 5.6 m2 g–1 for pristine BVO. At 75 °C, the sensor achieved a response (Ra/Rg) of 42.1 toward 50 ppm acetone, approximately 6.2-fold higher than that of pristine BVO, together with response/recovery times of 90/324 s. The enhancement is attributed to the combined effects of the porous framework, increased density of accessible adsorption sites, and heterointerface-mediated charge redistribution. These findings demonstrate that the BVO/g-CN heterostructure is a promising candidate for low-temperature, high-performance acetone sensing and offers an effective strategy for the rational design of semiconductor heterojunction-based gas sensors.