Construction of BiVO₄/Co-TCPP MOF/ITO photoelectrochemical sensor and sensitive detection of caffeine via chronoamperometry

Caffeine, a central nervous system stimulant ubiquitously present in many plants such as coffee and tea, is conventionally quantified using chromatographic and electrophoretic techniques. Despite the advantages of rapid response, simple instrumentation, and low cost, photoelectrochemical (PEC) sensing remains underdeveloped for caffeine analysis. In this study, a novel PEC sensor was constructed by integrating BiVO 4 nanoparticles with Co-TCPP MOF on ITO (BiVO 4 /Co-TCPP MOF/ITO), with the aim of caffeine detection. A series of structural, morphological, optical and photoelectrochemical analyses were conducted on the BiVO 4 /Co-TCPP MOF/ITO electrode. The results demonstrated that the incorporation of Co-TCPP MOF significantly enhanced the photoelectrochemical performance of the material attributable to their extensive π-conjugated system, achieving a photocurrent density of 2.01 mA/cm 2 at 0.6 V (vs. Ag/AgCl), approximately 3.3-fold higher than pristine BiVO 4 (0.59 mA/cm 2 ). After optimization of key parameters including Co-TCPP MOF dosage, electrolyte, applied bias, the sensor exhibited a robust linear response to caffeine in the range of 0.5–120 μM, with a detection limit of 0.12 μM. Moreover, it displayed excellent selectivity, reproducibility (RSD < 3.5%), and long-term operational stability. Application to real tea and coffee samples achieved satisfactory recoveries (95.8–103.2%), with results consistent with HPLC-MS/MS, confirming its reliability. This work provides an efficient PEC caffeine sensing platform and new insights for designing MOF-semiconductor hybrids for advanced optoelectronic sensing.