Browsing by Author "Zhou, Jingyi"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Computational chromatography: A machine learning strategy for demixing individual chemical components in complex mixtures
    (PNAS, 2022) Bajomo, Mary M.; Ju, Yilong; Zhou, Jingyi; Elefterescu, Simina; Farr, Corbin; Zhao, Yiping; Neumann, Oara; Nordlander, Peter; Patel, Ankit; Halas, Naomi J.; Laboratory for Nanophotonics
    Surface-enhanced Raman spectroscopy (SERS) holds exceptional promise as a streamlined chemical detection strategy for biological and environmental contaminants compared with current laboratory methods. Priority pollutants such as polycyclic aromatic hydrocarbons (PAHs), detectable in water and soil worldwide and known to induce multiple adverse health effects upon human exposure, are typically found in multicomponent mixtures. By combining the molecular fingerprinting capabilities of SERS with the signal separation and detection capabilities of machine learning (ML), we examine whether individual PAHs can be identified through an analysis of the SERS spectra of multicomponent PAH mixtures. We have developed an unsupervised ML method we call Characteristic Peak Extraction, a dimensionality reduction algorithm that extracts characteristic SERS peaks based on counts of detected peaks of the mixture. By analyzing the SERS spectra of two-component and four-component PAH mixtures where the concentration ratios of the various components vary, this algorithm is able to extract the spectra of each unknown component in the mixture of unknowns, which is then subsequently identified against a SERS spectral library of PAHs. Combining the molecular fingerprinting capabilities of SERS with the signal separation and detection capabilities of ML, this effort is a step toward the computational demixing of unknown chemical components occurring in complex multicomponent mixtures.
  • Thumbnail Image
    Item
    Plasmonically Enhanced Hydrogen Evolution with an Al–TiO2-Based Photoelectrode
    (American Chemical Society, 2022) Yuan, Lin; Kuriakose, Anvy; Zhou, Jingyi; Robatjazi, Hossein; Nordlander, Peter; Halas, Naomi J.; Laboratory for Nanophotonics
    Photoelectrochemical water splitting, as a method for producing clean hydrogen, could benefit from both plasmon-enhanced processes and the incorporation of earth-abundant materials in photoelectrode design. Here we report a n-TiO2/aluminum (Al) nanodisk/p-GaN photoelectrode sandwich device that exhibits enhanced H2 generation efficiencies due to a combination of plasmon-enhanced processes. Hot electrons generated in the illuminated Al nanodisk are injected into the conduction band of the TiO2 layer, subsequently transferring into water molecules adsorbed on the TiO2 surface, driving H2 evolution. The photocurrent densities we observe are nearly an order of magnitude higher than in an equivalent device with the Al nanodisk replaced with a Au nanodisk of the same size and are on par or better than previous reports of plasmonic photoelectrodes using Au nanoparticles in combination with cocatalyst species.
  • Thumbnail Image
    ItemEmbargo
    Theoretical Electromagnetic Study of Plasmonic Surface-Enhanced Raman (SERS) and Infrared Absorption Spectroscopies (SEIRA) Substrates
    (2024-04-16) Zhou, Jingyi; Nordlander, Peter; Tang, Ming
    Localized surface plasmon resonance (LSPR) has attracted interest because of its intriguing physical phenomena and is being explored for a wide range of applications including sensing, photocatalyst, display, and more. The localized field enhancement enables spectroscopy techniques like surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA) to detect and identify compounds, even in small amounts. For our investigation of the few-molecules region, we employed a novel statistical model to analyze the bianalyte spectra. Comprehensive electromagnetic simulations were carried out to locate areas of high electric field enhancement and gather relevant statistical information, facilitating the quantitative estimation of molecules. Subsequently, the SEIRA technique is introduced as a complementary method alongside SERS. When the substrate operates in the infrared region, strong electric field enhancement is generated by the lightning-rod effect. A new analytical model is proposed to provide further explanation of the field enhancement on the SEIRA substrate.