N-Doped MoS2 Nanoflowers for Efficient Cr(VI) Removal

The removal of Cr(VI) has attracted extensive attention since it causes serious harm to public health. Herein, we report a two-step method to synthesize N-doped MoS2 nanoflowers (NFs) with controllable sizes, which are first utilized for Cr(VI) removal and display outstanding removal performance. The N-MoS2 NFs with an average size of 40 nm (N-MoS2 NFs-40 nm) can rapidly remove Cr(VI) in 15 min under optimal conditions. The maximum adsorption capacity of N-MoS2 NFs-40 nm can reach 787.41 mg.g(-1), which is significantly larger than that of N-MoS2 NFs-150 and-400 nm (314.46 and 229.88 mg.g(-1)). Meanwhile, N-MoS2 NFs-400 nm have a higher maximum adsorption capacity than pure MoS2 NFs-400 nm (172.12 mg.g(-1)). In this adsorption/reduction process, N-MoS2 NFs have abundant adsorption sites due to a high surface area. N doping can generate more sulfur vacancy defects in the MoS2 NF structure to accelerate electron transfer and enhance the reduction of Cr(VI) to low-toxicity Cr(III). This study provides a facile approach to fabricating N-MoS2 nanoflowers and demonstrates their superior removal ability for Cr(VI).