Strong alternating piezoelectric field enhanced the piezocatalytic degradation of carbamazepine by a 3-chromophore material Cd4BiO(BO3)3 coupled ultrasound in water

How to efficiently treat a type of new emerging organic pollutant, carbamazepine (CBZ), with the features of environmental persistence, toxicity, and bioaccumulation, is now posing a challenge to scientists. Piezocatalysis, through the harvesting of mechanical energy, has a high capacity to degrade organic pollutants and is gaining increasing attention. Herein, a novel piezo material Cd4BiO(BO3)3 (CBB) with a 3-chromophore asymmetric structure showing an excellent CBZ degradation activity has been synthesized. The removal efficiency can reach 96.2% in 60 min, which is 4.13 times that of tetragonal phase BaTiO3 (BTO) under the same conditions. The superior catalytic performance can be attributed to the easily polarized 3-chromophore asymmetric structure units of CBB, d10 Cd2+ ion, stereochemically active lone pair of Bi3+, and π-delocalization of BO3, which can generate a very strong internal alternating piezoelectric field under the action of ultrasonic vibration. Driven by this internal electric field force, the excited free charges can be easily separated and transferred to the surface of the material to take part in the redox reactions. Besides, CBB also exhibits high stability and excellent removal efficiency for rhodamine B (Rh B) and tetracycline (TC). Hydroxylation and aldehyde oxidation are the main processes of CBZ degradation. The eco-toxicity of CBZ and its intermediates was evaluated using T.E.S.T. software. This study shows that the easily strongly polarized borate material has a potential application in the piezocatalytic degradation of organic pollutants.