MnCo₂O₄ Microflowers Anchored on P-Doped g-C₃N₄ Nanosheets as an Electrocatalyst for Voltammetric Determination of the Antibiotic Drug Sulfadiazine

In this work, hierarchically superior spinel crystalline manganese cobaltite (MnCo2O4) microflowers were hydrothermally synthesized to anchor on phosphorus-doped graphic carbon nitride nanosheet (MnCo2O4/P-CN) nanocomposites for the robust detection of the antibiotic sulfadiazine (SF). The structure and surface characteristics of the obtained composite were measured by the spectroscopic method, which collectively suggests the superior physical and chemical properties of the composite. The anodic oxidation of SF was considered at a glassy carbon electrode modified by MnCo2O4/P-CN (MnCo2O4/P-CN/GCE) using cyclic voltammetry (CV) and amperometry (i–t) techniques. A synergistic relationship between the high-quality flower-like MnCo2O4 and P-CN materials provides high electrical conductivity, larger surface area, and increased surface-active sites. The results indicate that MnCo2O4/P-CN/GCE shows excellent electrocatalytic activity toward the anodic oxidation of SF in pharmaceutical contaminants present in the environment at buffered pH 7.0. The proposed sensor via i–t and differential pulse voltammetry (DPV) results exhibits a wide linear range (LR: 0.008–207.57 and 0.01–95.40 μM), lower detection limit (LOD: 1.2 and 3 nM), and good sensitivity (9.28 and 49.28 μM μA–1 cm–2), respectively, as well as an excellent operational and cycle stability toward the electrochemical determination of SF. The unique structural features of a spinel crystalline MnCo2O4 microflower with symmetrical petals and six trunks can progressively enhance the electrochemical performance of the SF sensor. The state-of-the-art analysis of real samples confirms the possible utilization of Mn–Co-based sensors toward the monitoring of antibiotic residues, thus helping in assessing the behavior of pharmaceutical contaminants in the environment.