•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.Download high-res image (132KB)Download full-size image

•We demonstrate a novel strategy to improve the supercapacitive properties of CPs.•The supercapacitive properties of CPs can be boosted by electrodeposition of MoNiP.•The excellent performances of MoNiP coated CPs stem from its rational structure.We demonstrate a novel and universal strategy to significantly boost electrochemical performances of conducting polymer-based flexible supercapacitors via the relatively facile electrodeposition of MoNiP compounds. The fabricated MoNiP@polyaniline (PANI)@carbon fiber cloth (CFC) sandwiched hybrid, for instance, delivers 94.6% of specific capacitance retention from 1 to 40 mA cm−2 and 92.3% of specific capacitance retention at a high current density of 40 mA cm−2 after 2000 cycles, much greater than 56.8% and 58.3% for the uncoated PANI@CFC with MoNiP, respectively. With increasing the numbers for repeatedly alternate coating PANI and MoNiP layer by layer, the specific capacitances rise almost linearly. Simultaneously, the capacitance retentions maintain high levels at 40 mA cm−2 after 2000 cycles. A remarkable decrease in the charge transfer resistance and a markedly enhanced hydrophilicity with coating MoNiP on the surface of PANI@CFC can be found, which can greatly facilitate the electron and electrolyte ion transfer processes and thereby bring with it improved supercapacitive performance. Likewise, the supercapacitive performances of polypyrrole and poly(3,4-ethylenedioxythiophene) can be significantly enhanced in comparison with their MoNiP uncoated counterparts.Download high-res image (136KB)Download full-size image

In this work, a novel and facile one-pot method has been developed for the synthesis of a hybrid consisting of Ni–Mn–Co ternary oxide and poly(3,4-ethylenedioxythiophene)–polystyrenesulfonate (PEDOT–PSS/NMCO) with a hierarchical three-dimensional net structure via a solvothermal–coprecipitation coupled with oxidative polymerization route. Apart from the achievement of polymerization, coprecipitation, and solvothermal in one pot, the hydroxyl (OH–) ions generated from the oxidative polymerization of organic monomer by neutral KMnO4 solution were skillfully employed as precipitants for metal ions. As compared with the PEDOT–PSS/Ni–Mn binary oxide, PEDOT–PSS/Co–Mn binary oxide, and PEDOT–PSS/MnO2, PEDOT–PSS1.5/NMCO exhibits overwhelmingly superior supercapacitive performance, more specifically, a high specific capacitance of 1234.5 F g–1 at a current density of 1 A g–1, a good capacitance retention of 83.7% at a high current density of 5 A g–1 after 1000 cycles, an energy density of 51.9 W h kg–1 at a power density of 275 W kg–1, and an energy density of 21.4 W h kg–1 at an extremely elevated power density of 5500 W kg–1. Noticeably, the energy density and power density of PEDOT–PSS/NMCO are by far higher than those of the existing analogues recently reported. The exceptional performance of PEDOT–PSS/NMCO benefits from its unique mesoporous architecture, which could provide a larger reaction surface area, faster ion and electron transfer ability, and good structural stability. The desirable integrated performance enables the multicomponent composite to be a promising electrode material for energy storage applications.Keywords: 3D net structure; Ni−Mn−Co ternary oxide; PEDOT−PSS; supercapacitor; synthesis