▎ 摘　　要

It is an enormous challenge to explore multifunctional electrocatalysts for simultaneous detection of Cd(II), Cu (II), Hg(II) and hydrogen evolution reaction (HER). In this work, NiCo2O4 decorated N, S co-doped reduced graphene oxide composites (NCO/N, S-rGO) are synthesized via hydrothermal followed calcination process. The synergetic effect, oxygen vacancies and hybridization of NCO/N, S-rGO improve its excellent electrocatalytic performance for simultaneous and individual detection of Cd(II), Cu(II), Hg(II) and HER activity. When NCO/N, S-rGO is acted as heavy metal ions (HMIs) electrochemical sensors, it exhibits the high sensitivity and low detection limit for Cd(II) with 2.38 mu A mu M-1 and 123 nM, Cu(II) with 10.90 mu A mu M-1 and 14.4 nM, as well as Hg (II) with 5.41 mu A mu M-1 and 67 nM. NCO/N, S-rGO has outstanding stability and anti-interference performance and has been successfully implemented in the actual water environment. Furthermore, NCO/N, S-rGO also exhibits HER activity with overpotential and Tafel slope of 107 mV and 71.35 mV dec(-1), respectively. The electrochemical detection and HER activity mechanism of NCO/N, S-rGO are further investigated and demonstrated that the synergetic effect of NCO/N, S-rGO can improve its electronic microstructure and promote electrocatalytic performance. This work not only provides a simple method for the preparation of multifunctional electro-catalysts, but also enhances the comprehension of HMIs detection and HER mechanism.