Lack of highly efficient, inexpensive, and easily available catalysts severely limits the practical applicability of electrochemically sensing assay towards 5-hydroxytryptamine (5-HT). Herein, four kinds of Fe–Co bimetallic Prussian blue analogues (FeCo–PBAs) with different molar ratios of Fe to Co were prepared using a simple coprecipitation method. Interestingly, Fe(III) in K 3 [Fe(CN) 6 ] can be reduced to Fe(II) by adding trisodium citrate dehydrate, which could offer a new clue to synthesize PBAs with Fe(II) core ions. With the optimizational FeCo-PBA synthesized at a 0.5/1 M ratio of Fe to Co as an electrocatalyst , the constructed sensor shows excellent comprehensive performance for the 5-HT assay with a high sensitivity of 0.856 μA μM −1 and an ultralow detection limit of 8.4 nM. Under the optimum conditions, linearity was obtained in the ranges of 0.1–10.0 μM and 10.0–200.0 μM and preferable recoveries ranged from 97.8% to 103.0% with relative standard deviation (RSD) < 4.0%. The integrated properties of FeCo-PBA can be comparable to previously reported electrocatalysts for the 5-HT assay including noble metal-based and expensive carbon (graphene and carbon nanotubes)-based electrocatalysts. The proposed sensor also exhibits outstanding selectivity, reproducibility, and practicality for real sample analyses. This work is the first report on the PBA-based sensor for the 5-HT assay, verifying the practicability of this high-performance sensor for the 5-HT assay.
Formaldehyde is a significant indoor pollutant that poses serious risks to human health. Developing efficient, green, and renewable photocatalysts is considered one of the most promising strategies for indoor formaldehyde removal. In this work, we employed wood as a catalytic platform and successfully immobilized FeCo Prussian blue analogue nanoparticles (FeCo-PBA NPs) onto its surface. Subsequently, Fe-Co alloy-incorporated and N-doped wood-based carbonaceous photocatalysts (FeCoN@WC) were fabricated via pyrolysis. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to characterize the physico-chemical properties of the as-prepared FeCoN@WC. The results confirmed that FeCo-PBA NPs were successfully loaded onto the vessel walls of the wood, facilitating the formation of Fe-Co alloy and its incorporation into the carbon matrix during pyrolysis. Pyrolyzed FeCo-PBAs produced FeCo alloys and altered Fe/Co oxidation states. FTIR and XPS indicated that FeCoN@WC treated at 600°C had a stable structure with abundant catalytic sites, while XRD confirmed formation of intermediates favorable for photocatalysis. Moreover, FeCoN@WC showed excellent adsorption under dark conditions, with efficiency enhanced by 226.081 %. Meanwhile, the formaldehyde degradation under LED light was 6.796 % higher than in dark conditions. Furthermore, the first-order kinetic constant (k) was highest for FeCoN@WC prepared at 600°C, indicating optimal catalytic activity. Additionally, the FeCoN@WC demonstrated outstanding cycling stability, maintaining performance over multiple uses. This study presents a promising strategy for designing reusable wood-derived, PBA-based photocatalysts for sustainable indoor air purification.
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