MXene quantum dots decorated Ni nanoflowers for efficient Cr (VI) reduction

Nickel@MXene quantum dots (Ni@MQDs), as novel flower-like hybrid materials, were firstly prepared through a simple reduction method. The Ni@MQDs exhibited an outstanding catalytic performance for Cr (VI) reduction with a low activation energy (Ea = 18.9 kJ mol−1) and a high kinetic constant (k = 0.4779 min−1) in the presence of formic acid (HCOOH). Density functional theory calculations demonstrated that Ni@MQDs exhibited an upshift of d-band center of active Ni atoms to promote the adsorption of both HCOOH and active H atoms, as well as an improved conductivity to boost the catalytic reaction kinetics, leading to the most favorable catalytic performance. This work may open up a new avenue towards the design and synthesis of novel MQDs-based hybrid catalysts for wastewater treatment. [Display omitted] •A novel flower-like Ni@MQD hybrids was synthesized.•MQDs were used as a support for improving the stability of Ni NPs.•The Ni@MQDs exhibited a significantly enhancement in catalytic reduction of Cr (VI).•DFT calculations revealed the possible reaction mechanism.