Synergistic activation of P and orbital coupling effect for ultra-sensitive and selective electrochemical detection of Cd(II) over Fe-doped CoP

Despite significant advancements in the detection of cadmium (Cd(II)) based on nanomaterial adsorbability, limited research has been conducted on ultra-sensitive and selective detection mechanisms, resulting in a lack of guidance for designing efficient interface materials to detect Cd(II). Herein, reductive Fe doping on CoP facilitates an efficient Fe-Co-P electron transfer path, which renders P the electron-rich site and subsequently splits a new orbital peak that matches with that of Cd(II) for excellent electrochemical performance. The sensitivity of Cd(II) was remarkably up to 109.75 μA μM-1 on the Fe-CoP modified electrode with excellent stability and repeatability, surpassing previously reported findings. Meanwhile, the electrode exhibits exceptional selectivity towards Cd(II) ions compared to some bivalent heavy metal ions (HMIs). Moreover, X-ray absorption fine structure (XAFS) analysis reveals the interaction between P and Cd(II), which is further verified via density functional theory (DFT) calculation with the new hybrid peaks resulting from the splitting peak of P atoms coupled with the orbital energy level of Cd(II). Generally, doping engineering for specific active sites and regulation of orbital electrons not only provides valuable insights for the subsequent regulation of electronic configuration but also lays the foundation for customizing highly sensitive and selectivity sensors.