Dual-modal sensor for dopamine detection based on In 2 O 3 @FeMoSe 2 heterojunctions with excellent photoelectrochemical and peroxidase-like properties

Abstract In this work, the indium oxide and iron molybdenum selenide (In 2 O 3 @FeMoSe 2 ) heterojunctions were synthesized using a simple hydrothermal method. The morphological and structural properties of the obtained heterojunctions were comprehensively characterized. In-situ functionalization of the hierarchical micro-flowers of FeMoSe 2 with In 2 O 3 nanoparticles dramatically boosts electrical conductivity, photocatalytic activity and peroxidase-like activity. Benefiting from the band gap matching of In 2 O 3 and FeMoSe 2 , and dopamine (DA) as electron donors, and realizing photocurrent signals amplification. In the presence of H 2 O 2 , In 2 O 3 @FeMoSe 2 catalyzes the oxidation of 3,3',5,5'-tetramethylhydrogen dioxide (TMB) to a blue product. DA capture hydroxyl radicals, thereby inhibiting the oxidation of TMB, which leads to a lighter blue color and a subsequent decrease in absorbance. Here, a photoelectrochemical and colorimetric dual-mode sensor for dopamine assay based on In 2 O 3 @FeMoSe 2 was constructed. The detection limits were 14.7 nM and 0.19 µM (S/N = 3), respectively. The sensor was successfully applied to the detection of dopamine (DA) in human serum and urine samples, exhibiting high sensitivity, excellent reproducibility, and reliable stability. To the best of our knowledge, this strategy for DA detection has not been previously reported.