MoS2/Au0/N-CNT derived from Au(III) extraction by polypyrrole/MoS4 as an electrocatalyst for hydrogen evolution reaction.

The nanotube type MoS42-/polypyrrole (MoS4-Ppy) is newly synthesized which exhibits exceptional uptake capability for Au(III) with a high removal rate of >99.99% and large Kd of >107 mL/g. Through simple calcination, the Au-loaded MoS4-Ppy is successfully converted to nitrogen-doped carbon nanotubes (N-CNT) decorated with MoS2 nanosheets as well as Au0 nanoparticles, forming a novel composite of MoS2/Au0/N-CNT. The conductivity of MoS2/Au/N-CNT is substantially improved by the highly conductive N-CNT and Au0 metal. In addition, the N-CNT can effectively eliminate the aggregation of MoS2 sheets and Au0 particles, thus endowing more exposed active sites. The optimized MoS2/Au0/N-CNT displays good electrocatalytic performance towards hydrogen evolution reaction (HER). For the first time, we demonstrate the MoS4-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 MoS2/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.