Electrochemical Sensor Based on Co-Doped FePS3 Nanosheets for Ultra-Sensitive Detection of Dopamine in Human Serum

Abstract Electrochemical dopamine (DA) sensors become important for early diagnosis of psychiatric disorders like schizophrenia and Parkinson's disease due to their fast response, simplicity, and portability. However, traditional electrode modification materials such as noble metals and metal oxides have shortcomings such as high cost, low conductivity, or limited catalytic performance. Two-dimensional sulfide materials contribute to the smooth electrode reaction because of their ultra-high specific superficial area and favorable electrocatalysis properties, however, their low carrier mobility and poor electroconductibility limit the detection signal. In this paper, Co-doped FePS3 nanosheets were employed for DA detection for the first time. Fe0.9Co0.1PS3 nanosheets exhibited a detection limit of 120 nM, a linear range 0.25-100 μM and 120-500 μM, and possessed high recovery and reproducible stability when applied to human serum samples. Furthermore, according to the in-situ XPS characterization, S atoms located on the outmost layer of Fe0.9Co0.1PS3 nanosheets could be combined with the phenolic hydroxyl oxygen of DA, which makes electrode reaction from DA to dopamine quinone easier. Co-doping can further enhance the above effect, and increase the carrier mobility of FePS3 nanosheets. This work demonstrates that electrochemical sensors based on metal phosphorus trisulfide materials have tremendous potential for future application in mental disorder diagnosis