Donglin Xiang,Xiao Wang,Chun Ji,Laping He,Yuangen Wu,Han Tao
This study presents a novel electrochemical strategy for detecting organophosphorus pesticides based on the synergistic catalytic of red kidney bean esterase (RKBE) and iron–cobalt dual-atom catalyst embedded in N-doped carbon carrier (FeCo–NC). RKBE was extracted from the widely cultivated British red kidney beans ( Phaseolus vulgaris L.) . FeCo–NC exhibited excellent electrocatalytic and peroxidase-like activity, catalyzing o -phenylenediamine oxidation to produce electroactive 2,3-diaminophenazine, which served as signal probe generating a sensitive cathodic current. Notably, RKBE product 1-naphthol inhibited FeCo–NC activity, while organophosphorus pesticides counteracted this inhibition by suppressing RKBE activity, restoring the electrochemical signal of 2,3-diaminophenazine. Leveraging this signal-regulation mechanism, a dichlorvos sensor was developed, with wide linear range (50–50,000 pM), low detection limit (14 pM), and excellent real-sample recovery (93.33%–107.08%), demonstrating practical application potential. This study provides an affordable and easy-to-operate approach for large-scale on-site monitoring of organophosphorus pesticide residues in foods.
Ma Junjie,Liu Hangcheng,Tao Zeyu,Liu Jianfeng,Yuan Binxia,Pan Weiguo,Shi Zhengrong
In order to reveal the relationship between the structure and the electrochemical oxygen reduction reaction (ORR) activity of different double transition metal decorated catalysts, three different double transition metal and N co-doped carbon material cathode catalyst materials (FeCo–NC, FeNi–NC and CoNi–NC) were prepared in this study. The FeCo–NC catalysts synthesised in this study still showed high ORR activity under alkaline conditions, with a half-wave potential of 0.783 V RHE , a mass activity (MA) of 11.36 A/g (0.77 V RHE ) and an ultimate current density of − 4.46 mA cm −2 ; after 30,000 cycles, the half-wave potential only decreased to 99.3% of the initial potential. Meanwhile, we employ MS to establish three different double transition metal and N co-doped graphene catalysts and to calculate and analyse their desorption properties, leading to the FeCo–NC material being the model with the highest ORR activity, which is consistent with the experimental results. Graphical Abstract
Wang Yiyan,Zhang Guoxin,Ma Mang,Ma Yan,Huang Jiankun,Chen Chen,Zhang Ying,Sun Xiaoming,Yan Zifeng
An atomically dispersed FeCo-NC material with the 3D flower-like morphology was used as a unique substrate for the controllable deposition of ultrasmall NiFe layered double hydroxide nanodots (termed as NiFe-NDs) to simultaneously promote the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The size-limiting growth of NiFe-NDs (~4.0 nm in diameter) was realized via the confinement of the 3D flower-like mesoporous structure and the rich N/O functionality of FeCo-NC. Benefiting from the distinctive structure with the simultaneously maximum exposure of both OER and ORR active sites, the NiFe-ND/FeCo-NC composite showed an ORR halfwave potential of 0.85 V and an OER potential of 1.66 V in 0.1 mol L −1 KOH at 10.0 mA cm −2 . In-situ Raman analysis suggested the activity of OER was derived from the Ni sites on NiFe-ND/FeCo-NC. Moreover, the NiFe-ND/FeCo-NC-assembled Zn-air battery (ZAB) exhibited a very small discharge- charge voltage gap of 0.87 V at 20 mA cm −2 and robust cycling stability. Furthermore, the NiFe-ND/FeCo-NC composite was also applicable for fabricating all-solid-state ZAB to power wearable electronics with superior cycling stability under deformation. Our work could enlighten a new applicable branch of atomically dispersed metal-nitrogen-carbon materials as unique substrates for fabricating multifunctional electrocatalysts.
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