title: Scalable Synthesis of Ag Networks with Optimized Sub-monolayer Au-Pd Nanoparticle Covering for Highly Enhanced SERS Detection and Catalysis.
abstract: Highly porous tri-metallic AgxAuyPdznetworks with a sub-monolayer bimetallic Au-Pd nanoparticle coating were synthesized via a designed galvanic replacement reaction of Ag nanosponges suspended in mixed solutions of HAuCl4and K2PdCl4. The resulting networks' ligaments have a rough surface with bimetallic nanoparticles and nanopores due to removal of Ag. The surface morphology and composition are adjustable by the temperature and mixed solutions' concentration. Very low combined Au and Pd atomic percentage (1-x) where x is atomic percentage of Ag leads to sub-monolayer nanoparticle coverings allowing a large number of active boundaries, nanopores, and metal-metal interfaces to be accessible. Optimization of the Au/Pd atomic ratio y/z obtains large surface-enhanced Raman scattering detection sensitivity (at y/z = 5.06) and a higher catalytic activity (at y/z = 3.55) toward reduction reactions as benchmarked with 4-nitrophenol than for most bimetallic catalysts. Subsequent optimization of x (at fixed y/z) further increases the catalytic activity to obtain a superior tri-metallic catalyst, which is mainly attributed to the synergy of several aspects including the large porosity, increased surface roughness, accessible interfaces, and hydrogen absorption capacity of nanosized Pd. This work provides a new concept for scalable synthesis and performance optimization of tri-metallic nanostructures.
authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, and Institute of Materials Engineering, Nanjing University, Jiangsu, P. R. China.
authors.forename: Tianyu
authors.initials: T
authors.lastname: Li
authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, and Institute of Materials Engineering, Nanjing University, Jiangsu, P. R. China.
authors.forename: Sascha
authors.initials: S
authors.lastname: Vongehr
authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, and Institute of Materials Engineering, Nanjing University, Jiangsu, P. R. China.
authors.forename: Shaochun
authors.initials: S
authors.lastname: Tang
authors.affiliation: School of Materials Engineering, Nanjing Institute of Technology, Jiangsu, P. R. China.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Dai
authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, and Institute of Materials Engineering, Nanjing University, Jiangsu, P. R. China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Huang
authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, and Institute of Materials Engineering, Nanjing University, Jiangsu, P. R. China.
authors.forename: Xiangkang
authors.initials: X
authors.lastname: Meng