Hierarchical ZnVO/g-C3N4 Nanoflowers with a Mesoporous Architecture for Photoelectrochemical Detection of Dopamine

The development of photoelectrochemical (PEC) sensors for biosensing has become challenging due to the significant involvement of the recombination of electron–hole pairs, which affects the sensor’s sensitivity. Moreover, conventional PEC systems also suffer due to drawbacks in the photoactivated materials; generally, they have limited active sites, significant band gaps, limited light absorption, and fast charge recombination, resulting in a weak photocurrent response. In this work, a nanocomposite of 2D graphite carbon nitride (g-C3N4) and zinc vanadates (ZnVO) has been synthesized, which has a unique hierarchical nanoflower structure, where the nanopetals are the primary building blocks of the composite. The thin nanopetals provide large active sites for the adsorption of biomolecules on the nanocomposites, and their thin shape provides a short charge diffusion length. The experimental analysis reveals that the nanocomposite has more mesopores, which have a better charge transportation ability. Moreover, the band gap of the composite was calculated as 2.48 eV, and its light absorption ability at 481.45 eV makes it a promising candidate for PEC sensors. The PEC sensing of dopamine was conducted under light irradiation, and the photocurrent was recorded as continuously increasing. In contrast, the dopamine concentration increased, and the linear working range was 10–100 μM, with a small detection limit of 18.5 nM. The selectivity of the PEC sensor toward targeted dopamine was excellent in the presence of other species, and its reproducibility for 30 days showed satisfactory results. This research could provide valuable insights into developing a highly sensitive and selective PEC platform for biomolecule detection.