Modified Solvothermal Strategy for Straightforward Synthesis of Cubic NaNbO₃ Nanowires with Enhanced Photocatalytic H₂ Evolution

Abstract

To further improve the photocatalytic H₂ evolution activity, NaNbO₃ photocatalyts simultaneously possessing cubic crystal structure and 1D morphology have been successfully synthesized via a modified solvothermal strategy. During the process of synthesis employing ethylene glycol as solvent, a temperature fluctuation during the autoclaving period is proposed to regulate the grain growth without any other additives or calcinations. It is demonstrated that the structure-directing effect of the solvent is enhanced in the condition of the temperature fluctuation, contributing to the formation of 1D nanostructure. Otherwise, the irregular NaNbO₃ nanoparticles with severe aggregation resulted. Photocatalytic H₂ evolution activities of samples under ultraviolet light irradiation with 0.5 wt % of Pt cocatalyst indicate that NaNbO₃ nanowires expectedly exhibit an enhanced activity of 699 μmol h^–1 g^–1, approaching twice that of NaNbO₃ nanoparticles. The higher photocatalytic activity of NaNbO₃ nanowires is attributed to their large specific surface area, high chemical purity, and powerful reduction ability, which have been confirmed by the further characterizations and analysis based on crystal structure, valence state, elemental composition, and energy band structure. The modified solvothermal strategy provides an alternative pathway to regulate the crystal growth, which can effectively integrate the unique morphology with desired crystalline structure toward increasing photocatalytic activity