Portable photoelectrochemical platform with plasmon-enhanced S-scheme heterojunction for sensitive detection of mustard gas simulant

Chemical warfare agents (CWAs) are extremely toxic and pose serious threats, requiring highly sensitive and selective detection strategies. Herein, a plasmonic S-scheme heterojunction (Ag@PDI-OH/CN) combining perylene diimide (PDI-OH) and graphitic carbon nitride (CN) through strong π–π interactions is reported, which significantly enhances interfacial charge separation and transport. Incorporation of silver nanoparticles boosts light absorption via surface plasmon resonance, while the S-scheme built-in electric field suppresses charge recombination. The composite was fabricated into an all-in-one photoelectrochemical sensor, incorporating a compact detection module and wireless module for convenient portable detection, achieving ultralow detection of the mustard gas simulant CEES (93 nmol L⁻¹), excellent selectivity, and long-term operational stability over 100 cycles without performance degradation. These results highlight the critical role of π–π interactions in optimizing photoelectrochemical processes and provide a general strategy for high-performance PEC sensors for CWA detection.