Natural solar light-driven preparation of plasmonic resonance-based alloy and core-shell catalyst for sustainable enhanced hydrogen production: Green approach and characterization

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Plasmonic Co and/or Ag monometal and their combinations as bimetal alloy and core-shell nanoparticles were prepared under natural sun light, using aqueous glycerol (in-situ reducing agent) and TNP (stabilizer). The formation of bimetallic alloy and core-shell NPs, and their uniform dispersion on the surface of TNP were evidenced by different characterization techniques. Ultraviolet-visible diffuse reflectance spectroscopy evidenced the two distinct characteristic surface plasmon resonance (SPR) absorption bands for the core-shell nanoparticles and a single distinct characteristic SPR band for the alloy. X-ray photoelectron spectroscopy revealed the presence of Ag and Co in the metallic form. The results of H<SUB>2</SUB>-temperature programmed reduction of fresh and used samples emphasized the characteristic reduction peaks for the reduction of monometal/bimetal oxide to metallic/bimetallic particles. The interaction of the loaded bimetallic particles with TNP resulted in a shift in the Raman bands. The photoluminescence spectra of the used samples revealed the formation of bimetallic alloy and core-shell structures, which resulted in a decrease in the recombination of charge carriers. X-ray diffraction, electron paramagnetic resonance spectroscopy, high-resolution transmission electron microscopy, and cyclic voltammetry analyses substantiated the same. The monometal-loaded photocatalysts and the bimetal alloy and core-shell nanoparticle-loaded photocatalysts were further examined for H<SUB>2</SUB> production with pure water/aqueous glycerol/crude glycerol under natural solar light irradiation. The (Ag-Co)<SUB>coloaded</SUB>TNP catalyst yielded the maximum H<SUB>2</SUB> evolution rate of 63 mmol g<SUP>−1</SUP>. For comparison, experiments were conducted under artificial solar light irradiation with similar experimental conditions. Based on the results, different mechanistic paths for insitu photoreduced Ag-Co bimetallic alloy and core-shell nanoparticles on TNP for H<SUB>2</SUB> production are envisaged.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co/Ag bimetal alloy and core-shell are synthesized by in-situ photoreduction. </LI> <LI> Ag<SUB>core</SUB>@Co<SUB>shell</SUB> loaded TiO<SUB>2</SUB> exhibited enhanced H<SUB>2</SUB> production under sun light. </LI> <LI> Different aqueous scavengers are tested for H<SUB>2</SUB> production under solar light. </LI> <LI> Alloy and core-shell NPs act as electron sink and efficiently suppress the recombination. </LI> <LI> The formation mechanism of bimetal alloy and core-shell structures were discussed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>