Dual templated synthesis of tri-modal porous SrTiO3/TiO2@ carbon composites with enhanced photocatalytic activity

Abstract

Semiconductor photocatalysis is considered as an effective sustainable technology to relieve the emerging global energy shortage issues, while how to design the efficient photocatalyst with enhanced light absorption, charge carrier separation and surface reaction is still a primary barrier for its applications. Herein, SrTiO3/TiO2/C (STC) heterostructure with tri-modal (micro-, meso-, macro-) pores integrated was synthesized via freeze casting combined with silica colloid as the hard template. Carbon was used as the photosensitizer for extending light absorption, electric field from SrTiO3/TiO2 for enhancing charge carrier separation, and hierarchical pore structures for promoting surface reaction. Silica in different particle sizes was used to tune the pore structure of composites. The as-prepared STC sample reached the photocatalytic hydrogen production rate from water splitting as high as 2.52 mmol h−1 g−1 under UV irradiation, which is 1.5 times of benchmark catalyst P25. Its reactivity for methylene blue (MB) degradation is superior to the corresponding individual compositions and about 4.7 times of SrTiO3 under UV light irradiation. The current work provides a feasible method to fabricate the hierarchical porous multi-component semiconductor based heterostructures with excellent photochemical performances, which develops our understanding for the design and fabrication of hierarchical porous catalysts.