Preparation of mesoporous crack-free Sb-SnO2 xerogels through ambient-pressure drying and its application as three-dimensional electrode

Abstract

Ambient-pressure-dried (APD) crack-free Sb-SnO2 xerogel has been developed through a facile sol-gel approach. Propylene oxide was added into the tin and antimony precursors to cause rapid formation of the wet gel, which was then modified with silica and dried under ambient pressure. A silica modification carried out by soaking the wet gel in TEOS/ethanol solution, in combination with solvent exchange, allowed to avoid the risky and costly supercritical drying (SCD) process. The silica possessed dual-functional effects during the synthesis process as surface silylation agent and underlying silica structure. FT-IR, SAXS, TEM, and nitrogen physisorption analysis revealed a favorable silica dispersion, outstanding specific surface area (254 m2 g−1), pore volume (0.52 cm3 g−1), and ideal pore size (8.75 nm) for the products. The key properties of the APD crack-free Sb-SnO2 xerogel were compared with that of SCD aerogel at the same synthesis conditions. Finally, the electrochemical behaviors of 3D electrochemical system filled with the as-synthesized materials as particle electrodes were investigated, which with regard to voltammetric charge and polarization impedance. Padding of the crack-free Sb-SnO2 xerogels yielded a voltammetric charge 2.99 times as large as that of conventional electrochemical system, and decreased the charge transfer resistance from 46.19 to 6.39 Ω, which realize intrinsically enhanced electrochemical performance for 3D electrochemical system.