Calcium silicate hydrate decorated by Fe, Ti co-modified birnessite direct multi-component photocatalyst: Design, preparation and photocatalytic performance under visible light irradiation

Abstract

Constructing a multi-component structure is an effective strategy to promote the formation of oxygen vacancies (OVs), which can enhance electron transition to improve the photocatalytic activity of materials. In this work, it was designed a series of novel photocatalysts supported on calcium silicate hydrates (C-S-H) via density functional theory calculation. These designed photocatalysts were then synthesized and marked as Bir@C-S-H, TiO2/Bir@C-S-H, and α-Fe2O3/TiO2/Bir@C-S-H, respectively. In comparison to other catalysts, α-Fe2O3/TiO2/Bir@C-S-H photocatalyst has a higher specific surface area, a lower band gap, more OVs, which can activate more dioxygen molecules, and more reactive radicals. The photocatalytic activity of as-synthesized photocatalysts was verified by using HCHO as the target pollutant. To the treatment of 80 ppm HCHO, the α-Fe2O3/TiO2/Bir@C-S-H exhibits 100% HCHO conversion corresponding gas hourly space velocity of 60 L/(g•h) with a relative humidity of 60% under visible light irradiation, while Bir@C-S-H and TiO2/Bir@C-S-H present 89.92% and 94.17% HCHO conversion, respectively at same conditions. This work demonstrates a more effective calcium silicate hydrate decorated by Fe, Ti co-modified birnessite heterostructures for HCHO oxidation, which can be directly used as decorative materials, providing a novel guidance for practical application.