High efficiency Hg(II) electrochemical detection based on the number of defect engineering on MoS2: Insight in synergistic action of sulfur vacancies and undercoordinated Mo.

ABSTRACT

Defects on nanomaterials can effectively enhance the performance of electrochemical detection, but an excessive number of defects may have an adverse effect. In this study, MoS2 nanosheets were synthesized using a hydrothermal synthesis method. By controlling the calcination temperature, MoS2-7H, calcined at 700 °C under H2/Ar2, exhibited an optimal ratio of "point" defects to "plane" defects, resulting in excellent detection performance for mercury ions (Hg(II)). In general, the sulfur vacancies (SV) and undercoordinated Mo generated after calcination of MoS2 significantly promotes the adsorption process and redox of Hg(II) by increasing surface chemical activity, providing additional adsorption sites and adjusting surface charge status to accelerate the catalytic redox of Hg(II). The prepared MoS2-7H-modified electrode showed a sensitivity of 18.25 µA µM-1 and a low limit of detection (LOD) of 6.60 nM towards Hg(II). MoS2-7H also demonstrated a good anti-interference, stability, and exhibited a strong current response in real water samples. The modulation to obtain appropriate number of defects in MoS2 holds promise as a prospective electrode modification material for the electroanalysis.