Optimising the structure of mesoporous niobium oxide using evaporation-induced self-assembly synthesis method

To increase the photocatalytic performance of Niobium(V) oxide (Nb 2 O 5 ) it is necessary to increase its accessible surface area. The evaporation-induced self-assembly (EISA) synthesis method is well suited for the synthesis of mesoporous structures, but the optimisation of synthesis parameters for Nb 2 O 5 is still limited. In this study, we demonstrate that the synthesis parameters — duration of evaporation, airflow rate, relative humidity and water content in the reaction mixture — significantly affect the specific surface area, mesoporous structure and photocatalytic performance of isopropanol oxidation into acetone of Nb 2 O 5 . Our results show that a combination of long evaporation duration, low airflow rate, low relative humidity and moderate water content are needed to obtain material with the highest specific surface area (145 m 2 g −1 ) and a narrow hysteresis loop in the N 2 sorption isotherm. This material exhibits four times higher photocatalytic activity compared to materials synthesised under less favourable conditions (14.3–17.7 μmol h −1 compared to 3.7 μmol h −1 ). We also show that the ordered mesoporous structure plays an important role in improving the photocatalytic performance: the materials with a higher degree of order exhibit about two times higher activity than the materials with a lower degree of order with the same specific surface area (10.4–12.1 μmol h −1 compared to 4.9–7.9 μmol h −1 ). These results provide valuable insights for optimising the synthesis of mesoporous niobium oxide to increase both the specific surface area and photocatalytic performance. • Optimising surface of mesoporous Nb 2 O 5 for isopropanol photooxidation. • Low humidity and low airflow rate are crucial for high specific surface area. • Well-ordered Nb 2 O 5 performs better in photooxidation than less ordered.