Synthesis of self-assembled spindle-like CePO4 with electrochemical sensing performance†
Three different morphologies of CePO4 nanocrystals (rods, columns, and spindle-like assembled nanosheets), spindle-like LaPO4, spindle-like PrPO4, and TbPO4 microspheres were successfully synthesized using a hydrothermal method. Interestingly, the morphology of the self-assembled spindle-like CePO4 underwent a change from big spindles to short spindles, to a cluster of spindles, and finally to spindle-like assembled nanocrystals with the increase of time. Using a single-step process, the nanocrystals were fixed on the surface of a glassy carbon electrode (GCE) using a Nafion membrane solution, which increased the specific surface area and electron transfer rate. The presence of CePO4, especially the spindle-like assembled nanosheet CePO4 (S-CePO4), greatly improved the effective surface area of the GCE, thereby increasing the conductivity of the GCE-based electrochemical sensor. The highly ordered superstructures of S-CePO4 were assembled from homogeneous spindles with an average length of 100 nm and a center diameter of approximately 50 nm. The use of the S-CePO4 sensor resulted in a 229% increase of the specific surface area (compared with that of the bare GCE-based sensor) and excellent electrocatalytic performance toward the electrochemical oxidation of hydroquinone (HQ), catechol (CC), and resorcinol. The linear range and detection limit for the determination of CC were 0.07 and 20–1200 μM, respectively. Our findings demonstrate the potential of the S-CePO4@GCE-based electrochemical sensor for the simultaneous determination of CC and HQ. The morphology and structure of S-CePO4 reduced the resistance significantly and increased the effective active surface area and the electrolyte contact area, making it more advantageous to the utilization of the active components.