Prussian Blue Microcrystals with Morphology Evolution as a High-Performance Photo-Fenton Catalyst for Degradation of Organic Pollutants

The morphology-dependent property of crystal materials has aroused extensive attention and raised high requirements for subtly tailoring the morphology of micro-/nanocrystals. Herein, we develop an in situ etching method for preparation of Prussian blue (PB) microcrystals with morphology evolution by progressively increasing the concentration of chloroplatinic acid in the reaction system. These PB microcrystals with controllable morphologies are employed as photo-Fenton reagents to degrade organic pollutants. PB hexapods (PB-hpds) and PB hexapod stars present superior catalytic performance to pristine PB microcubes and other PB intermediates with truncated corners or edges because of their high specific surface areas and adequate exposure of Fe ^III -NC coordination active sites. In the reusability test, the reused PB-hpds present more efficient catalytic performance for rhodamine B decomposition compared with the pristine catalyst. According to more investigations, the reasonable mechanism is proposed that Fe ^III -NC exhibits higher catalytic activity than Fe ^II -CN in the specific coordination environment. The increased content of surface Fe ^III -NC coordination active sites is the key factor in accelerating the decomposition of H ₂ O ₂ and enhancing the photo-Fenton performance of PB-hpds. Several operating parameters including catalyst dosage, H ₂ O ₂ concentration, pH value, and reaction temperature are evaluated in detail. Classical quenching experiments and electron paramagnetic resonance measurements further reveal that HO ^• should be responsible for high performance of catalysts. This work will be significant for tailoring the morphology of the materials and arousing more attention to enhance the stability and reusability of catalysts.