One-step conversion of Bi(NO3)3 ⋅5H 2 O system toward Bi5O7NO3 nanoneedles with photoactivity influenced by the butanol solvent

Abstract

Microsheets, nanoneedles, and spider-web morphology of the Bi5O7NO3 system were obtained from the direct transformations of Bi(NO3)3⋅5H2O source by a simple solvothermal method, replacing partially the water with butanol solvent in the presence of ethylenediamine. The influence of the butanol solvent concentration on the changes in the nanocrystalline structure, optical, morphological and textural properties of the obtained bismuth-based materials was characterized by X-ray diffraction, Fourier transform IR analysis and scanning electron and transmission microscopies (SEM and HRTEM). The model conversion of the Bi(NO3)3⋅5H2O source is discussed in terms of dehydration and interactions with the particle's surface. The optical properties were analyzed by diffuse reflectance spectroscopy, and the UV-visible absorption capacity was correlated with the irradiance of the UV-visible lamp. The photocatalytic activity of bismuth-based materials was investigated using an indigo carmine dye solution under operational conditions that maintain high light penetration and transport coefficients, resulting in a low particulate photocatalyst load. The observed highest adsorption and photoactivity of the Bi5O7NO3 system was attributed to its physicochemical properties, primarily to population of grain boundaries of the spherical nanocrystals, to the increasing in the specific surface area and to the high dispersion capacity of Bi5O7NO3 needles, where the dye discoloration reaction operates in the kinetic regime by pseudo zero order.