MoS/Au/N-CNT derived from Au(III) extraction by polypyrrole/MoS as an electrocatalyst for hydrogen evolution reaction.

The nanotube type MoS/polypyrrole (MoS-Ppy) is newly synthesized which exhibits exceptional uptake capability for Au(III) with a high removal rate of >99.99% and large K of >10 mL/g. Through simple calcination, the Au-loaded MoS-Ppy is successfully converted to nitrogen-doped carbon nanotubes (N-CNT) decorated with MoS nanosheets as well as Au nanoparticles, forming a novel composite of MoS/Au/N-CNT. The conductivity of MoS/Au/N-CNT is substantially improved by the highly conductive N-CNT and Au metal. In addition, the N-CNT can effectively eliminate the aggregation of MoS sheets and Au particles, thus endowing more exposed active sites. The optimized MoS/Au/N-CNT displays good electrocatalytic performance towards hydrogen evolution reaction (HER). For the first time, we demonstrate the MoS-Ppy is a promising material for efficient extraction and recovery of trace amounts of precious metal Au from gold-bearing leachates, and the subsequent product MoS/Au/N-CNT can act as an effective HER electrocatalyst. The fabrication process of the composite material can not only remediate water contamination but also reuse precious metals. This dual-use approach opens a new way to explore effective sorbents for recovery of trace of gold and apply them in catalysis and sensing fields.