Impact of Ultrasmall Platinum Nanoparticle Coating on Different Morphologies of Gold Nanostructures for Multiple One-Pot Photocatalytic Environment Protection Reactions

Here, we report the preparation of various morphologies of core-satellite hybrid plasmonic nanomaterials of gold and platinum, viz., the coating of platinum nanoparticles on gold nanostars (Pt@AuNSs), nanospheres (Pt@AuNPs), and nanorods (Pt@AuNRs) for visible-NIR-sunlight illuminated highly efficient photoconversion of CO2 to HCOOH and visible light mediated degradation of various organic dyes (methylene blue, methyl orange, and methyl red) in a single step at room temperature. In comparison, Pt@AuNSs shows higher conversion efficiency for CO2 photoconversion to HCOOH with 1.52% of quantum yield and 2.58% of chemical yield in visible-light illumination. There was a 200-fold increase in the conversion efficiency after PtNP coating to AuNSs. On the other hand, Pt@AuNPs (quantum yield = 1.44%) and Pt@AuNRs (quantum yield = 0.64%) also show the significant conversion rate in visible and NIR light, respectively. All the hybrid nanoparticles were found to be stable, whereas PtNPs increase the stability of AuNSs incredibly, during the photoconversion reaction and reused for five CO2 reduction reaction cycles without losing photocatalytic activity. Moreover, Pt@AuNSs also showed higher photocatalytic activity for organic pollutant degradation and degraded methylene blue, methyl red, and methyl orange in 45, 75, and 80 min with 0.104 min-1, 0.055 min-1, and 0.044 min-1 reaction rate, respectively. The results highlighted the crucial role of PtNPs as a highly efficient cocatalyst as well as the impact of increases in surface area with the change in morphology of gold nanostructures on CO2 photoconversion and organic dye degradation.