Multidimensional Ternary Heterostructured Self-Precipitated Ag Nanoparticles on TiO₂@SrTiO₃ for Photoreforming of Plastics Face Mask to Hydrogen

Solar-to-hydrogen via the photocatalytic reaction has been considered a promising way to obtain sustainable green energy in this generation. In the past three years, the COVID-19 pandemic changed our life habits and led people produce waste of personal surgical masks daily. Photoreforming of plastics waste to hydrogen contributes to lowering the environmental load and provides another route of sustainable energy acquirement. In this study, we prepared the ternary photocatalysts with heterostructure construction of zero-dimensional SrTiO₃ nanocubes (SrTiO₃ NC) and one-dimensional TiO₂ nanofibers with self-precipitating Ag nanoparticles (AT NFs). AT NFs synthesized by hydrothermal method showed the unique Ag NPs on the surface of TiO₂ NFs, increasing the absorption. Via in-situ hydrothermal growth reaction of SrTiO₃ NC, we precisely manipulate the distribution of SrTiO₃ NC on AT NFs by tuning the proportion of strontium titanate. As a high proportion of SrTiO₃, the one-dimensional structure of AT@SrTiO₃ gradually weakened, and the self-precipitated Ag nanoparticles were covered as dopants in the AT@SrTiO₃. From the morphology observation and the study of XPS and XAS spectra to investigate interface bonding information, we noticed that several SrTiO₃ NC covered the silver particles, and partial Ag NPs were retained on AT@ SrTiO₃ with specific concentration, maintaining the excellent photoresponse due to surface plasma resonance of Ag NPs. The photocatalytic hydrogen production rate in a mixture of water/ethanol under xenon lamp irradiation can reach 320.8 μmol●g^-1●h^-1. In addition, for the photoreforming of the surgical mask to hydrogen production, we carried out the hydrolysis pretreatment in an alkaline solution and then used UV ozone to activate PP and PE molecules. Both pretreatments were beneficial to the hydrolysis and polarity that showed the hydrogen production to 316.9 μmol●g^-1●h^-1.