Interfacial Doping of Heteroatom in Porous SnO₂ for Highly Sensitive Surface Properties

The design and synthesis of heteroatom-doping porous materials with unique surface/interfaces are of great significance for enhancing the sensitive surface performance in the fields of catalytic energy, especially gas sensor, CO oxidation, and ammonium perchlorate decomposition. Usually, the template method followed by a high-temperature calcination process is considered as the routes of choice in preparing ion-doped porous materials, but it requires extra templates and will undergo complicated steps. Here, we present a simple fusion/diffusion-controlled intermetallics-transformation method to synthesize various heteroatom-doping porous SnO₂ only by changing the species of intermetallics. By this new method, Ni-doped popcornlike SnO₂ with plenty of ∼30 nm pores and two kinds of Cu-doped SnO₂ nanocages was successfully constructed. Phase-evolution investigations demonstrated that growth kinetics, diffusion, and solubility of the intermediates are highly related to the architecture of final products. Moreover, low-solid-solution limit of MO (M: Ni, Cu) in SnO₂ made the ion dope close to the surface to form a special surface/interfaces structure, and selective removal of MO produce abundant pores to increase the surface area. As a consequence, Ni-doped composite exhibits higher sensitivity in formaldehyde detection with a relative low-operating temperature in a short response time (i.e., 23.7-50 ppm formaldehyde, 170 °C, and 5 s) and Cu-doped composites show excellent activity in decreasing the catalytic temperature of CO oxidation and ammonium perchlorate decomposition. The fusion/diffusion-controlled intermetallics-transformation method reported in this work could be readily adopted for the synthesis of other active heteroatom-doping porous materials for multipurpose uses.