Mussel-inspired PDA/Ag nanocomposite catalyst for highly-efficient Cr(vi) removal via visible light-induced reduction and absorption

Abstract

Toxic pollutants containing Cr(VI) are unavoidable in industrial production. Photoreduction is commonly performed during the removal of Cr(VI) by reducing Cr(VI) to Cr(III). In this work, polydopamine/Ag-nanoparticles (PDA/AgNPs) were synthesized under mild conditions through the self-polymerization of PDA and the in situ reduction of Ag⁺ to Ag nanoparticles via PDA. The relevant structural characterizations were confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical characterizations were performed through photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopy (EIS) performance. PDA/AgNPs-2 (2.5 mg) catalysts showed outstanding catalytic ability with a 98% removal ratio after 60 min illumination. Unique adhesion behavior and the good electrical conductivity of PDA/AgNPs led to the excellent removal performance of Cr(VI) via absorption and photo-induced reduction. The PDA/AgNPs were acceptably reused after 7 cycles. This work provides a feasible reference to synthesize photocatalyst materials for removing hazardous Cr(VI).