Recently, field effect transistor type N,N-dimethylformamide (DMF) sensors have been widely studied, but semiconductor resistance type DMF gas sensors have not been reported as much. Herein, porous LaFeO3 nanoparticles were prepared by reverse co-precipitation, and the gas sensing detection performance of material was studied. The sensor based on LaFeO3 calcined at 750℃ shows excellent response (Rg/Ra=189.2), great selectivity, and long-term stability to 100 ppm DMF at the operating temperature of 170℃. The effects of different calcination temperatures (650℃, 750℃, 900℃) on the structure and properties of LaFeO3 were compared. The structural characterization data revealed that LaFeO3 calcined at 750℃ has the appropriate specific surface area and abundant active sites, which plays a key role in promoting the adsorption and decomposition of target gas. In addition, the surface of the LaFeO3 calcined at 750℃ has the highest concentration of adsorbed oxygen, which also provides an excellent environment for gas-sensitive reactions on the surface of the material. Therefore, LaFeO3 is expected to be a potential novel material in DMF detection.

Graphite carbon nitride possesses great promise for visible photocatalysis, but the bulk carbon nitride prepared from nitrogen-rich precursors such as melamine has inherent drawbacks such as retarded photogenerated carrier migration and exciton effects, which limit its application. Herein, we constructed a novel Boron nitride quantum dots modified carbon-defects ultra-thin porous carbon nitride (BNQDs/Vc-UPCN). The double channels were constructed by carbon-defects structure and Boron nitride quantum effect to overcome its inherent drawbacks and applied to the photodegradation of common persistent organic pollutants (methylene blue). The structure, porosity, elemental composition, optical properties, photoelectrochemical properties, and photocatalytic properties of the prepared BNQDs/Vc-UPCN composites were investigated using various characterization methods. Meanwhile, the results of radical trapping experiments and electron spin resonance characterization demonstrated that BNQDs/Vc-UPCN promote molecular oxygen activation more than Vc-UPCN did. In terms of degradation effect, the best sample (BC-1) is 10 times more effective than the initial sample (BCN). This study proposes an effective mechanism for constructing novel visible-light-driven photocatalysts using carbon-defects ultra-thin structures and quantum dots, which can be used for the treatment of organic pollutants.