Zinc is an essential micronutrient for plants, playing a crucial role in metabolic and physiological processes, enzyme activation, and ion homeostasis [1]. Zn deficiency disrupts plant metabolism, leading to stunted growth and impaired nutrient uptake, which can ultimately contribute to Zn deficiency in the human diet. Conversely, excessive Zn exposure reduces germination vigor and biomass, decreasing crop yield and quality [2]. To ensure optimal Zn fertilization, precise monitoring of Zn levels in plant tissues and growth substrates is necessary to enhance fertilization efficiency and prevent overapplication.
Currently, Zn determination in plant tissues relies on atomic spectroscopy techniques after acid digestion [3], [4], a method that requires specialized personnel, laboratory analysis, and lengthy processing times. Electrochemical sensors offer a promising alternative, enabling rapid, accurate, and on-site Zn measurement, thereby improving data availability for real-time fertilization management.
In this study, we investigate polyethylenimine-derived laser-induced graphene (PEI-LIG) as an electrode material for trace-level Zn²⁺ detection using square wave anodic stripping voltammetry (SWASV). PEI-LIG is fabricated using two different laser sources: a 532 nm laser and a CO₂ laser (10.6 μm). We assess how the laser wavelength influences the morphology, surface chemistry, and electrochemical performance of the resulting LIG. Raman spectroscopy is used to evaluate graphene quality, while X-ray photoelectron spectroscopy (XPS) provides insights into surface chemistry modifications. Morphology and elemental composition are examined through scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). Furthermore, the electrochemical properties of PEI-LIG are characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Finally, the developed sensing material is applied for the detection of Zn2+ using SWASV.