Microdroplet confined assembly enabling the scalable synthesis of titania supported ultrasmall low-valent copper catalysts for efficient photocatalytic activation of peroxymonosulfate

Abstract

The synthesis of highly dispersed low-valent copper catalysts is very challenging because they are prone to oxidation and sintering. Herein, scalable synthesis of ultrafine Cu(0)/Cu(I) catalysts supported on mesoporous titania microspheres is enabled by a one-step microdroplet confined assembly method. The extremely fast solute assembly in the microdroplet induces excellent metal precursor dispersion, reduces sol–gel crosslinking, and creates wrinkled microspheres with surface crusts and hollow cavities. This structural architecture allows the generation of an inner reductive gas environment during calcination in air to reduce Cu(II) and create oxygen vacancy (O_V) sites in titania. The obtained catalysts exhibit excellent performance in the photocatalytic activation of peroxymonosulfate (PMS) for pollutant degradation. The Cu(0) species with a surface plasmon resonance effect and O_V-rich anatase facilitate efficient solar light utilization and charge separation. The intimate interface between Cu(I)/Cu(0) and anatase enables fast electron transfer and timely copper redox cycling to promote the activation of PMS.