Urease Mediated Synthesis of Crystalline Porous Tin Oxide at Room-temperature and Applications in Lithium-ion Batteries and Gas Sensors

In the absence of urea, urease is demonstrated to catalyze the hydrolysis and polycondensation of the SnCl2 aqueous system to form crystalline mesoporous SnO2 at room temperature. The resulting SnO2 has a high specific surface area of 231 similar to 248 m(2) g(-1) with uniform pore size at 3.3nm, and the porous structure show high thermal stability. Interestingly, the urease is not co-precipitated with the tin oxide but is left in solution, which indicates the high purity of tin oxide and the possibility for urease recovery. The characterization of inter-mediates and final products reveal the key feature of strategy presented in this study is the stabilization of an amorphous tin oxide phase by urease and its subsequent transformation to crystalline tin oxide; the phase transformation and removal of water might be the major reasons for pores forming process. And the obtained tin oxides exhibit not only enhanced electrochemical performance in lithium ion battery, but also better sensitivity toward hydrogen.