Two-dimensional MXene enabled carbon quantum dots@Ag with enhanced catalytic activity towards the reduction of p-nitrophenol

Abstract

A composite of cuttlefish ink-based carbon quantum dots@Ag/MXene (CQD@Ag/MXene) was firstly synthesized by solvothermal method as a catalyst for reduction of p-nitrophenol (PNP) to p-aminophenol (PAP). CQD@Ag/MXene was characterized by scanning electron microscopy (SEM), field emission transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman. The results show that loading on 2D material MXene can prevent the aggregation of CQD@Ag and expose more active sites, which contributes to a superior catalytic activity with a pseudo-first-order rate constant k (2.28 × 10⁻² s⁻¹) and mass-normalized rate constant k_m (5700 s⁻¹ g⁻¹), nearly 2 times higher than CQD@Ag without MXene (k = 1.09 × 10⁻² s⁻¹ and k_m = 2725 s⁻¹ g⁻¹). Besides, CQD@Ag/MXene showed excellent reusability which even retained about 65% activity in successive 10 cycles. The high adsorption rate to PNP and the promotion of forming H radicals may be the reason for the outstanding catalytic activity of CQD@Ag/MXene. CQD@Ag/MXene can be a potential candidate in the removal of environmental pollutants due to its facile synthesis and high catalytic efficiency.