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• Fe-[(HEDP)(2MI)] 2 had lower detection limit than Fe-HEDP, with enzymatic activity of more than 95%. • Introducing N element could realize the anchoring of Fe, and provided more metal active sites. • Coral-like structure with unique corner defects could provide abundant surface and expose more active sites. • ·OH was the main active species detection of H 2 O 2. Hydrogen peroxide (H 2 O 2) was closely related to environmental pollution and cell damage. It's of great significance to use a simple colorimetric method to achieve efficient and rapid detection of H 2 O 2. Fe-HEDP (prepared with etidronic acid monohydrate) and Fe-[(HEDP)(2MI)] x (prepared with etidronic acid monohydrate and 2-methimidazole) were synthesized by DBD plasma method, and applied as artificial peroxidase in the detection of hydrogen peroxide (H 2 O 2). The different molar ratios of metals and organic ligands, as well as the introduction of N element, had great influence on the detection performance of H 2 O 2. Fe-[(HEDP)(2MI)] 2 synthesized with the molar ratios of metal and organic ligands of 2:1 exhibited excellent performance. Fe-[(HEDP)(2MI)] 2 exhibited a coral-like morphology shape composed of nanorods with abundant angular defects, which could provide more active sites. Fe-[(HEDP)(2MI)] 2 also exhibited higher content of graphite-N and surface oxygen, which could anchor more Fe, thereby promoting the Fenton reaction. Fe-[(HEDP)(2MI)] 2 showed an excellent linear relationship (R 2=0.998) in the H 2 O 2 concentration range of 0–500 μM with an LOD of 80 μM. Radical trapping experiments were carried out, proving that ·OH was the main active species, and the detection mechanism was proposed. Therefore, Fe-[(HEDP)(2MI)] 2 provided a new material for realizing efficient and rapid detection of H 2 O 2. [Display omitted] [ABSTRACT FROM AUTHOR]

The conventional hydrothermal bottom-up synthesis for preparing carbon dots (CDs) usually requires stringent conditions and high energy consumption, whereas the quantum yield (QY) of CDs remains at a relatively low level. Herein, CDs exhibiting strong blue photoluminescence (PL) with an ultra-high QY (up to 94.4%) were prepared via a simple one-step microwave-assisted route using citric acid (CA) and o-phenylenediamine (o-PD) as precursors. The operating conditions, including reaction time, solvent species, amount of solvent, and precursor molar ratio, were optimized. The CDs synthesized within 3.5 min of microwave heating in ethylene glycol (EG) at a CA-to-PD molar ratio of 5:1 exhibited the highest QY (94.4%). A synergistic PL mechanism of the molecule state and carbon core state emissive centers was proposed according to the characterization results of CDs. Moreover, the proof-to-concept H 2 O 2 fluorescent detection performances of the prepared CDs confirmed their great application potential as probe materials. Through directly mixing the CD products and H 2 O 2 , a strong PL response could be rapidly detected after merely 1 min, and the detection limit was calculated to be as low as 8.6 nM. Besides, the CDs exhibited high biocompatibility, making them suitable for in-vivo detection of H 2 O 2. Therefore, this work provides a novel and efficient approach for synthesis of ultra-high QY CDs that can be directly applied in biological detection. [Display omitted] • A simple and rapid one-step CDs synthesis method within 3.5 min is proposed. • Various operation conditions are optimized. • The PL QY of fabricated CDs can reach as high as 94.4%. • The fabricated CDs can be directly applied for H 2 O 2 detection within 1 min • The detection limit for H 2 O 2 could descend to only 8.6 nM. [ABSTRACT FROM AUTHOR]