Photocatalytic Atomization of the Elemental Species in Solution for Atomic Fluorescence Spectrometry

We report a paradigm shift in the atomization of the elemental species in solution using a novel Z-scheme GaP@N-TiO₂ nanocomposite in the presence of formic acid under visible-light irradiation (<i>vis</i>-GaP@N-TiO₂-HCOOH), replacing standalone cool diffusion flame-based atomizers presently in use. The atoms formed can be detected in solution by atomic fluorescence spectrometry (<i>is</i>AFS) with at least 1 order of magnitude improvement in the limits of detection at the pg mL^-1 level for As, Se, Hg, Zn, Cd, Ni, Fe, Pb, and Co. During this process, the reductive CO₂^•- switched from HCOOH by the valence band h⁺ preserved on N-TiO₂ together with the conduction band e^- on GaP plays a synergistic reduction role. Such a new paradigm shift in atomization is expected to challenge the existing norms of atomic spectrometry and give rise to the next-generation <i>is</i>AFS and beyond, no longer using the flame atomizer(s), avoiding the use of hazardous chemical(s) and/or harmful UV rays, as well as eliminating the inefficient processes of either sample nebulization and isolation of ultrafine droplets and/or chemical vapor species generated.