ABSTRACT
Solar-to-steam (STS) generation based on plasmonic materials has attracted significant attention as a green method for producing fresh water. Herein, a simple in situ method is introduced to fabricate Au nanoparticles (AuNPs) on cellulose filter papers as dual-functional substrates for STS generation and surface-enhanced Raman spectroscopy (SERS) sensing. The substrates exhibit 90% of broadband solar absorption between 350 and 1800 nm and achieve an evaporation rate of 0.96 kg·m-2·h-1 under 1-sun illumination, room temperature of 20 °C, and relative humidity of 40%. The STS generation of the substrate is stable during 30 h continuous operation. Enriched SERS hotspots between AuNPs endow the substrates with the ability to detect chemical contamination in water with ppb limits of detection for rhodamine 6G dye and melamine. To demonstrate dual-functional properties, the contaminated water was analyzed with SERS and purified by STS. The purified water was then analyzed with SERS to confirm its purity. The developed substrate can be an improved and suitable candidate for fresh water production and qualification.
ABSTRACT
We present a numerical study on a 2D array of plasmonic structures covered by a subwavelength film. We explain the origin of surface lattice resonances (SLRs) using the coupled dipole approximation and show that the diffraction-assisted plasmonic resonances and formation of bound states in the continuum (BICs) can be controlled by altering the optical environment. Our study shows that when the refractive index contrast Δn < -0.1, the SLR cannot be excited, while a significant contrast (Δn > 0.3) not only sustains plasmonic-induced resonances but also forms both symmetry-protected and accidental BICs. The results can aid the streamlined design of plasmonic lattices in studies on light-matter interactions and applications in biosensors and optoelectronic devices.
