Highly stable MoS2@PDA composite for enhanced reduction of AuCl4−

• The AuCl 4 − reduction by MoS 2 @PDA composite was studied. • MoS 2 @PDA composite exhibited excellent stability. • The coating of PDA on MoS 2 enhanced its AuCl 4 − reduction capacity. MoS 2 has attracted tremendous attention in reducing AuCl 4 − , however, it suffers from poor stability in solutions. In this work, MoS 2 nanosheet wrapped with polydopamine (MoS 2 @PDA composite) was successfully prepared by simple hydro-thermal synthesis. Compared to pure MoS 2 , the as-synthesized MoS 2 @PDA composite exhibited not only excellent stability, but also superb AuCl 4 − reduction capacity. With the warp of PDA, the thermal stability of the composite was improved obviously, and dissolution of the composite in aqueous solution hardly occurs. Moreover, the reduction of AuCl 4 − by MoS 2 @PDA composite could reach equilibrium in 90 min, and the maximum reduction was about 3800 mg/g, and the reaction was intensely pH-dependent. In addition, gold nanoparticles were widely distributed on the surface of MoS 2 @PDA composite, which could effectively prevent the agglomeration of gold nanoparticles. This finding might point out the possibility of applying MoS 2 @PDA composite as stable anti-agglomeration substrate for gold nanoparticles.