Aurivillius-type layered Bi2MoO6 with surface defects: A robust electrocatalyst for trace vanillin detection

초록

Reliable and real-time detection of vanillin in environmental and food samples is essential for food quality control, authenticity assessment, and environmental safety. In this study, a defect-engineered bismuth molybdate (Bi2MoO6 or BiMoO) electrocatalytic platform was developed for the rapid and sensitive electrochemical detection of vanillin. Bi2MoO6 was synthesized through a hydrothermal-assisted calcination route and comprehensively characterized using X-ray diffraction with Rietveld refinement, Raman spectroscopy with depth profiling, and X-ray and ultraviolet photoelectron spectroscopy to investigate its crystal structure, lattice distortion, and surface defect chemistry. The synthesized material exhibited a layered Aurivillius structure with distorted MoO6 octahedra and defect-rich oxygen vacancy sites, which significantly enhanced interfacial charge transport and adsorption-controlled electrocatalytic activity toward vanillin oxidation. When modified onto a screen-printed carbon electrode (Bi2MoO6/SPCE), the sensor demonstrated enhanced electrochemical sensing performance a wide linear detection range of 0.01-561 mu M, a low LOD of 0.83 nM and LOQ of 2.77 nM. In addition, the fabricated sensor exhibited high selectivity, long-term operational stability, and good reproducibility. Practical applicability was successfully validated through vanillin quantification in real environmental and food samples, including river water, pond water, and chocolate samples, achieving recoveries close to 100% with relative standard deviations below 3%. These findings demonstrate that defect-engineered Bi2MoO6 is a promising electrocatalytic material for sensitive and reliable real-time vanillin monitoring and provides an effective strategy for the development of advanced Aurivillius oxide-based electrochemical sensors.

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