Insights into the Effect of Cation Distribution at Tetrahedral Sites in ZnCo₂O₄ Spinel Nanostructures on the Charge Transfer Ability and Electrocatalytic Activity toward Ultrasensitive Detection of Carbaryl Pesticide in Fruit and Vegetable Samples

Abstract

The recent advancement in designing novel spinel nanostructures has opened virtually infinite possibilities for the development of high-performance electrochemical sensors to detect target species. The electrocatalytic activity of spinel structures can be enhanced by tuning the cation distribution; however, the role of cation distribution at tetrahedral ions on the electrochemical sensing responses has rarely been considered. Herein, the effect of cation distribution at tetrahedral sites (T d ) in the spinel nanostructure ZnCo 2 O 4 on the electrochemical sensing performance toward carbaryl (CBR) was first investigated. The ZnCo 2 O 4 nanoflake samples with different cation ratios of Zn/Co at tetrahedral sites were designed by using a facile solvothermal method. We found that a higher Zn ion content at tetrahedral sites significantly enhanced the electron transfer ability through the electrolyte/electrode interface. More interestingly, a higher Co ion ratio between octahedral sites and tetrahedral (Co Oh /Co Td ) promoted the electrochemical oxidation process of CBR with a higher catalytic rate constant (k cat ). Under optimized conditions, the ZnCo 2 O 4 -NF-based electrochemical nanosensor showed a linear response from 0.15 to 100 μM with a limit of detection of 0.05 μM and a high electrochemical sensitivity of 2.04 μA μM −1 cm −2 . The designed nanosensor also exhibited good repeatability, long-time stability, high anti-interference ability, and excellent recovery with fruit and vegetable samples. Furthermore, this study offers insights into the cation distribution-dependent electrocatalytic activities of spinel nanostructures, which is helpful to the design of advanced spinel nanostructure-based electrocatalysts for improving the electrochemical sensing performance.

Effect of Aspect Ratio of a Gold-Nanorod-Modified Screen-Printed Carbon Electrode for Carbaryl Detection in Three Different Samples of Vegetables

“…The absorption capacity of each modified electrode can be calculated from the values of the observed slope of I pa versus v for SPCE-A400, SPCE-A600, and SPCE-A800 being 3.18 × 10 –5 , 2.2 × 10 –5 , and 1.22 × 10 –5 mol cm –2 , respectively. In comparison, previous works have determined the value of adsorption capacity of electrochemical sensors based on modified electrodes for carbaryl detection and obtained comparable results with our work. , Based on these results, it can be concluded that the modified electrodes based on SPCE-modified AuNR400 displayed the largest capacity for carbaryl adsorption on the electrode surface among other developed electrodes.…”

“…The mechanism of carbaryl oxidation on the surface of SPCE-modified AuNRs can be deduced following the two processes: (1) the hydrolysis of carbaryl molecules into 1-naphthol in an alkaline condition and (2) the oxidation of hydroxyl (OH – ) functional groups within the 1-naphthol chemical structure by removing 1 electron and 1 proton (H + ) with the corresponding anodic oxidation peak at 0.2 V. The mechanism of carbaryl oxidation at the surface of SPCE-modified AuNR is illustrated in Figure d. Furthermore, recent studies demonstrated the oxidation of 1-naphthol using SPCE-modified metal nanoparticles, and the metal oxide composite occurs at 0.4 V as reported in ref and at 0.5 V as reported in ref . Based on this result, it can be inferred that the SPCE-modified facet-controlled anisotropic gold nanoparticles provide faster electron transfer kinetics to oxidize carbaryl molecules than bare SPCE.…”

“…In comparison, previous works have determined the value of adsorption capacity of electrochemical sensors based on modified electrodes for carbaryl detection and obtained comparable results with our work. 93,94 Based on these results, it can be concluded that the modified electrodes based on SPCE-modified AuNR400 displayed the largest capacity for carbaryl adsorption on the electrode surface among other developed electrodes.…”

Visible Light as a Promising Signal Amplification Tool for the Efficient Electrochemical Detection of Azithromycin Antibiotic by Using Photoactive Spinel Nickel Ferrite Nanoflakes

“…More interestingly, most of the nano/microflakes are connected through both edge-to-flat-surface and edge-to-edge conjunctions, which can be applied as an outstanding electro-bridge to promote electron transfer between the electrode and analyte, and thus enhancing the electrochemical sensing performance. 25 Electrochemical properties of unmodified and NFO-modified SPE electrodes.-To define the role of NFO NFs in enhancing peak current response as well as electrochemical active surface area and reducing peak-to-peak potential, the electrochemical performance of unmodified and modified SPE electrodes was scrutinized by CV technique in a benchmark redox probe Fe(CN) 6 ] 3-/4at a scan rate of 50 mV s -1 . Figure 2a illustrates the CV curves of the bare SPE and NFO/SPE in 0.1 M KCl containing 5 mM [Fe(CN) 6 ] 3-/4-.…”

An on-site and portable electrochemical sensing platform based on spinel zinc ferrite nanoparticles for the quality control of paracetamol in pharmaceutical samples

“…27–29 In recent work, our group developed a series of electrochemical sensors based on AFe 2 O 4 (A = Zn, Co, Mn, Ni, Cu), BCo 2 O 4 (B = Zn, Cu), and ZnFe 2 O 4 /ZnO hetero-nanostructures for the highly sensitive detection of various types of analytes including chloramphenicol, furazolidone, carbaryl, and clenbuterol. 30–34 Therefore, the electrochemical sensing platform and spinel oxide nanostructures are expected to provide a promising combination for quickly and accurately analysing as well as quantifying pharmaceutical tablets.…”