Low-dimensional black phosphorus (LDBP) materials have emerged, with considerable application potential in sensing due to their unique folded structures and remarkable physicochemical properties. These include anisotropies, layer-dependent and tunable band gaps, high carrier mobilities, high current switching ratios, and excellent electron donor capacities. As a type of supporting material that is favorable to signal transmission or reception, LDBP is widely researched in piezoelectric, flexible, chemical, and biomolecular sensors. This review summarizes the synthetic methods, properties, and modification strategies of LDBP, and then mainly focuses on the research progress in LDBP-based sensor applications, including physical and chemical sensors and biosensors. The major issues in LDBP-based sensor applications are also discussed. Finally, the prospects and challenges in the field of LDBPbased sensors are analyzed.

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Silver nanoparticles (AgNPs)-based nanozyme sensors are gaining attention for rapid on-site H 2 O 2 detection, which is beneficial to disease diagnosis and environmental monitoring. However, the severe agglomeration of AgNPs on the electrodes significantly reduced electrochemical catalytic activity. In this work, we fabricated N-doped Ti 3 C 2 MXene (named Ag/NÀ Ti 3 C 2 ) deposited with three-dimensional flower-like AgNPs to achieve ultrasensitive H 2 O 2 detection. N doping strategy is employed to improve the conductivity of MXene, and the corresponding catalytic activity of Ag/NÀ Ti 3 C 2 is enhanced by optimizing the growth process and morphology. The Ag/NÀ Ti 3 C 2 /glassy carbon electrode (Ag/N-Ti 3 C 2 /GCE) sensor exhibited a wide H 2 O 2 detection range (0.05-35 mM), a low limit detection (1.53 μM), and 3.1 % relative standard deviation in 50 repeated cyclic voltammetry measurements. The results above indicate that catalytic activity of metal nanozymes could be influenced by the substrate and both materials jointly determine the sensor's performance. As a result, N-doped MXene is an attractive candidate for biological sensing and other electrocatalytic applications.

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