Self-reductive palladium nanoparticles loaded on polydopamine-modified MXene for highly efficient and quickly catalytic reduction of nitroaromatics and dyes

Palladium nanoparticles (PdNPs) with average particle size of 10 nm were deposited on the surface of Ti3C2 (MXene) using polydopamine (PDA) as the stabilizer by in-situ self-reduction mechanism. A series of characterization methods were used to analyze the morphology and microstructure of the resulting composite catalyst (Ti3C2-PDA@PdNPs). The catalytic performance of the composite catalysts toward 2-nitrophenol (2-NP), 4-nitro phenol (4-NP), methyl orange (MO) and methylene blue (MB) were systematically investigated. The results indicate that Ti3C2-PDA@PdNPs exhibits highly efficient and quickly catalytic reduction activity. Specifically, it takes only 70 s for Ti3C2-PDA1.0 @PdNPs to catalyze the complete conversion for 2-NP. The reaction rate constants of Ti3C2-PDA1.0 @PdNPs for these four pollutants are calculated as k(2-NP) = 0.1536 s(-1), k(4-NP) = 0.1245 s(-1), k(MO)= 0.2014 s(-1), and k(MB)= 0.0732 s(-1). In addition, after 10 recycles of catalytic reduction, the catalytic efficiency of Ti3C2-PDA1.0 @PdNPs can be still maintained above 92%, and the loss of PdNPs in each cycle is not more than 1.2%, indicating that Ti3C2-PDA@PdNPs composite catalyst has high stability and recyclability. This work provides a new, green and simple synthesis idea for MXene nanocomposite catalyst, and provides a good application prospect for the catalytic degradation of nitroaromatic compounds and dyes.