Accumulation-Driven Surfactant-Free Synthesis of Architectured Immiscible Metallic Nanoalloys with Enhanced Catalysis

Accumulation-mediated chemical reactions are a ubiquitous phenomenon in nature. Herein, we explore microbubble-induced accumulation of precursor ions to achieve surfactant-free synthesis of immiscible metallic nanoalloys and to simultaneously pattern the nanoalloys into targeted architectures for their enhanced catalytic applications. We name our approach as a unified spatiotemporal synthesis and structuring (US3) strategy, wherein millisecond-scale accumulation of the precursor ions in a highly confined laser-mediated microbubble trap (MBT) drives ultra-fast alloy synthesis in sync with the structuring process. As a case-in-point, we employ US3 strategy for the in-situ surfactant-free synthesis and patterning of traditionally immiscible rhodium-gold (RhAu) nanoalloys. Stochastic random walk simulations justify the millisecond-scale accumulation process, leading to a 3-order reduction in synthesis time. The catalytic activity and structure-property relationship of the structured nanoalloys were evaluated using the reduction of p-nitrophenol with NaBH4. Our in-situ synthesis and structuring strategy can be translated for high-throughput production and screening of multi-metallic systems with tailored catalytic, opto-electronic, and magnetic functions.