Visible-light-driven hierarchical porous CeO2 derived from wood for effective photocatalytic degradation of methylene blue

Abstract

To improve the photodegradation efficiency of organic dyes under visible light, a novel bio-inspired photocatalyst was designed herein based on the theory of wood-bionics. Graded porous cerium oxide with wood structure (W–CeO2) was prepared by using larch wood splinters as the template. W–CeO2 maintains the structure of the wood. W–CeO2 showed many advantages such as low consumption, high performance, and long-term stability for application as a photocatalyst. In this study, the morphological features, crystalline structure, specific surface area, chemical composition, carrier separation efficiency and optical properties of the as-developed photocatalyst were investigated comprehensively. The results show that W–CeO2 completely replicated the multi-scale hierarchical pore structure of the wood template. Compared with cerium oxide prepared by the traditional hydrothermal method (0-CeO2), the specific surface area of W–CeO2 was doubled, and the average pore diameter was reduced by 73% to 5.38 nm. Moreover, W–CeO2 showed the characteristics of anisotropy, circular electron diffraction pattern, reduced crystallinity, and higher charge separation efficiency. W–CeO2 also possessed higher electronic activity, greater active oxygen content, and lower electron-hole recombination efficiency. Methylene blue (MB) dye was used as the target pollutant to test the photocatalytic performance of W–CeO2. The MB degradation test results show that using wood as a template greatly improved the catalytic efficiency of the catalyst. The main free radicals involved in the reaction were determined by adding 1,4-benzoquinone (BQ) and tert-butanol (TBA) for comparative experiments. The results of this work can provide new insights into the construction of bio-inspired materials for promoting the photocatalytic reaction of organic dyes and indicate that W–CeO2 photocatalyst is a promising candidate for wastewater treatment application.