A chemical bottom-up and successive top-down approach for nanoporous SnO₂ hollows from Ni₃Sn₂ nanoalloys: High surface area photocatalysts and anode materials for lithium ion batteries

This work shows that a chemical bottom-up and successive top-down approach is a good synthetic strategy for nanoporous hollow materials. The heating of 3 eq. nickel chloride and 2 eq. tin chloride at 280°C in the presence of oleylamine resulted in the formation of intermetallic Ni₃Sn ₂ alloy materials. According to mechanistic studies, zerovalent nickel formed by the reduction of precursor induced the reduction of the tin precursor to form Ni₃Sn₂ alloys. The Ni₃Sn ₂ nanoparticles were characterized by SEM, TEM, PXRD and EDS. When the Ni₃Sn₂ nanoparticles were treated with 1% nitric acid for 48 hours, the nickel component was completely etched. The resultant materials were nanoporous SnO₂ hollow materials, which were characterized by TEM, PXRD and XPS. Due to the nanoparticulate characteristics of shells, BET analysis on the SnO₂ hollows showed nanoporosity and a high surface area of 101 m² g^-1. The hollow SnO ₂ materials with nanoparticulate shells showed excellent photocatalytic activities in the decomposition of Rhodamine B. Moreover, they showed promising electrochemical performances with a discharge capacity of 560 mA h g^-1 after 30 cycles and stabilities as anode materials in lithium ion batteries. The preparation of a multi-component alloy and the selective etching strategy can be further expanded to other intermetallic alloy systems for the development of functional materials.