Laddered type-1 heterojunction: Harvesting full-solar-spectrum in scavenger free photocatalysis

Preparation of scavenger free, solar photocatalyst is challenging for large-scale dye-degradation. We report for the first time, a novel solar photocatalyst with laddered type-1 heterojunction. Photocatalyst was realised by selective deposition of a fine ZnO shell onto nanospherical, mesoporous zinc ferrite core using a special two-step microwave-assisted-solvothermal-technique. Synthesis and processing conditions were tuned to harvest entire solar spectrum owing to oxygen vacancies. Under direct sunlight our photocatalyst completely degraded Rhodamine-B without the need for hole scavenger. Scavenging and probing-tests implied the participation of hydroxyl, and superoxide-radicals for Rhodamine-B degradation. NIR light absorption played a vital role in the photodegradation along with the laddered transitions enabled by well positioned bands that avoid recombination. The catalyst was tested for the reproducible activity upto 5 reuse cycles without loss of significant activity. Our approach utilizes (i) direct sunlight (ii) relatively inexpensive and (iii) reusable materials for scavenger free dye degradation and encourages a viable route for ideal solar-photocatalyst.