Vertical 3d Printed Pd/Tio 2  Arrays Induced Spontaneous Micro-Vortexes For High Efficiency Photo-Assisted Catalytic Water Treatment

Abstract

Catalytic degradation of organic contaminants is at the frontier of water treatment due to its selectivity, energy savings and ability to convert harmful contaminants into harmless or even valuable chemical products for recycling. Photo-assisted catalytic reduction is of specific interest in this regard, as it is able to utilize abundant solar energy to enhance catalytic performance. Nevertheless, achieving sufficiently high performance in the catalytic removal of organic contaminants for practical application at the field scale is still extremely challenging. Herein, we report a Pd-decorated TiO2 (Pd/TiO2) hierarchical vertical array for fast and efficient catalytic water treatment. Such a forest-like Pd/TiO2 vertical array demonstrates the following distinct advantages over conventional planar or bulk catalytic systems: 1) abundant anchoring sites for Pd nanocrystals loading as-well-as sufficient catalytic active sites; 2) spontaneous micro-vortex generated by the vertical pillars blocking the water flow can significantly enhance the contact opportunities between the organic contaminant and the catalyst; 3) high sunlight absorption; and 4) efficient mass transfer channels for the reactants and products. As a proof of concept, the Pd/TiO2 array demonstrated rapid and efficient photo-assisted catalytic reduction of high concentrations of 4-nitrophenol wastewater (2 g·L-1, ~ 14.38 mM) and its feasibility for continuous flow wastewater treatment. The TOF value of the Pd/TiO2 array is up to 8.00 min-1, which is approximately 4.2 times than that of planar Pd/TiO2 film with the same area (1.91 min-1). Our strategy of embellishing nanocatalysts on a 3D printed hierarchical vertical array provides a promising approach to boost the catalytic performance of various catalysts for different chemical reactions.

Keywords: 3D printing, TiO2, Hierarchical vertical array, Catalytic water treatment, 4-Nitrophenol