Efficient electron confinement and enhanced plasmonic support of Pt nanoparticles to AuNPs-SnO₂ heterojunction for highly selective artificial photosynthesis

The development of high-performance plasmonic photocatalysts is essential for advancing artificial photosynthesis and sustainable CO₂ utilization. This study reports the synthesis of morphologically stable, perfectly monodispersed Pt-SnO₂@AuNPs core-satellite heterostructures for the efficient reduction of CO₂ to formic acid (HCOOH). The heterostructure, comprising 3–5 nm of SnO₂ nanoparticles and 3–5 nm of Pt nanodots on a AuNPs core, was engineered to maximize electron density and facilitate the rapid transport of high-energy hot charge carriers across the solar spectrum. Experimental results demonstrate that the anisotropic heterostructure significantly enhances photocatalytic activity compared to traditional benchmarks. Under visible light, the quantum yield (QY) and chemical yield (CY) for HCOOH formation reached 2.156% and 3.666%, respectively. Optimized performance was observed at a catalyst dosage of 0.6 mg/mL, yielding an ultimate QY of 3.385% and, CY of 5.755%, and solar-to-fuel efficiency of 5.241%. Furthermore, the Pt-SnO₂@AuNPs exhibited broad-spectrum activity under both NIR and sunlight. DFT studies confirmed the superior electronic influence of the Pt-SnO₂@AuNPs surface, identifying SnO₂ as a highly effective n-type semiconductor support for promoting charge separation and HCOOH selectivity. The engineered photocatalyst demonstrated exceptional durability, maintaining structural integrity and activity over ten recycling cycles across a wide pH range (5–11) and a one-year shelf life. This work highlights the synergistic effects of plasmonic hot carrier emergence, a high-energy boost through electron density enhancement by SnO_2, and rapid electron transportation by Pt, providing a robust platform for efficient solar-to-fuel conversion.