Facile synthesis of MnO2-embedded flower-like hierarchical porous carbon microspheres as an enhanced electrocatalyst for sensitive detection of caffeic acid

- The novel hybrid of flower-like porous MnO2/MC was fabricated by a simple strategy.
- MnO2/MC shows superior electrocatalytic properties for the oxidation of caffeic acid.
- The MnO2/MC-based sensor shows excellent performance for the caffeic acid detection.
- This proposed method was successfully used to detect caffeic acid in tablets and fruits.

Tailored designs/fabrications of hierarchical porous advanced electrode materials are of great importance for developing high-performance electrochemical sensors. Herein, we demonstrate a simple and low-cost in situ chemical approach for the facile synthesis of MnO2-embedded hierarchical porous carbon microspheres (MnO2/CM). By the characterizations of scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction and energy dispersive spectroscopy, we evidenced that the synthesized product were flower-like carbon microspheres (CM) assembled by the bent flakes with thickness of about several nanometers and MnO2 nanorods were highly dispersed and successfully decorated on the CM layers, resulting in a rough surface and three-dimensional microstructure. The greatest benefit from the combined porous CM with MnO2 nanorods is that the MnO2/CM modified electrode has the synergetic catalysis effect on the electro-oxidation of caffeic acid, leading to the remarkable increase in the electron transfer rate and significant decrease in the over-potential for the caffeic acid oxidation in contrast to the bare electrode and CM modified electrode. This implies that the prepared MnO2/CM can be employed as an enhanced electrocatalyst for the sensitive detection of caffeic acid. Under the optimum conditions, the anodic peak current of caffeic acid is linear with its concentration in the range of 0.01-15.00 μmol L−1, and a detection limit of 2.7 nmol L−1 is achieved based on S/N = 3. The developed sensor shows good selectivity, sensitivity, reproducibility, and also excellent recovery in the detections of real samples, revealing the promising practicality of the sensor for the caffeic acid detection.

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