Porous Copper Foam‐Based Plasmonic Nanocrystals Modified 3D Semiconductor Nanoflowers for Multifold, Recyclable, and Portable Detection of Environmental Contaminant

A multifunctional solid-state surface-enhanced Raman scattering (SERS) nanoarray exhibiting superior detection sensitivity with high stability and reproducibility has been a hotspot since it provides multiple analyses and on-site detection platform. Herein, porous Cu foam-based plasmonic nanocrystals modified 3D mixed phase TiO2 nanoflowers heterojunction for the effective photodegradation under visible-light exposures is fabricated. Firstly, TiO2 nanoflowers composed of many upright one-dimensional TiO2 nanopillars possess the merits of a large specific surface area and optical absorption. These nanopillars not only restrain the recombination of electron-hole pairs by shortening the diffusion length of minority carrier to the TiO2 surface, but also are favorable for the carrier transport in the one-dimensional nanostructure. Secondly, the introduction of plasmonic nanocrystals with localized surface plasmon resonance effect will boost the overall photoabsorption of TiO2 nanopillars and strengthen the electromagnetic field around the Ag nanocrystals, thus promoting the SERS effect. Under visible-light excitation, the hot electrons generated by the nonradiative transition of Ag nanocrystals (approximate to 50 nm) transfer to TiO2 to participate in the photocatalytic reaction, which improves the degradation efficiency of pollutants. The ultrasensitive and recyclable substrates displayed by this platform may lay a foundation for rapid detection analysis on environment toxicity when coupled with a portable Raman device.