Defect-engineered g-C3N4/CsCu2I3 nanoheterojunctions with S-scheme charge transfer for enhanced gas & thermal-sensing

Rational integration of selective growth of CsCu 2 I 3 with rod-shaped and graphitic carbon nitride (g-C 3 N 4 ) nanoparticles was implemented by anti-solvent-assisted crystallization method and calcination. Therefore, a novel nitrogen vacances (V N ) defects enriched g-C 3 N 4 /CsCu 2 I 3 (CN/CCI) nanoheterostructure was expected prepared. The study revealed that the synergistic effect between the type-II and S-scheme charge transfer (CT) mechanisms and the strong adsorption capacity afforded by abundant surface V N defects significantly enhances the catalytic reaction efficiency. This synergy endows the CN/CCI heterojunction with superior performance compared to individual semiconductors. The interfacial charge transfer mechanisms (type-II and S-scheme) and the ultrafast dynamic processes in CN/CCI nano-heterojunctions were proposed and evaluated using nanosecond time-resolved transient photoluminescence spectroscopy and in-situ X-ray photoelectron spectroscopy. Following this scheme, the distinctive configuration of CN/CCI-6 heterojunctions demonstrated remarkable sensitivity reaching 5.66 in response towards 40 ppm of NO 2 operating at room temperature under ultraviolet-visible light activation, which is nearly 8.3 and 5.8 times greater than the sensitivity observed with pristine CsCu 2 I 3 and pure g-C 3 N 4 , respectively. Furthermore, the CN/CCI-6 nanoheterostructures also exhibited fastest response/recovery time (27.3 s/37.8 s) characteristics than that of pristine CsCu 2 I 3 (34.3 s/47.5 s) and pure g-C 3 N 4 (33.6 s/45.9 s). Additionally, we propose that the temperature - dependent photoluminescence of CN/CCI-6 could be exploited for the evaluation of the thermal-sensing with max sensitivity of 0.0093 K −1 at 550 K, indicating the CN/CCI nanoheterostructure is well suited for wide-range temperature sensing. The synergistic effect arising from the formation of V N defects and the efficient S-scheme CT manner within the CN/CCI nanoheterojunction holds significant implications and serves as an important reference for the development of high-performance gas & thermal-sensing.