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As an important detection technology, how to realize the rapid detection of H2O2 is very important for the early diagnosis of some diseases. Herein, octahedral porous carbon composites containing Cu and MoO2 are prepared by using bimetallic metal–organic frame (MOF) NENU-5 as precursor. It is found that Cu and MoO2 nanoparticles of Cu-MoO2-C are uniformly dispersed in the porous carbon framework. For the electrochemical detection of H2O2, compared with the Cu-C composite without MoO2, Cu-MoO2-C shows stronger redox ability, higher sensitivity (121 μA mM−1 cm−2), and lower detection limit (95.5 nM). In addition, Cu-MoO2-C also shows strong anti-interference ability and H2O2 detection sensitivity in the presence of a variety of interference substances. Our work proves that MoO2 has a good H2O2 reduction ability, and it also proves that the H2O2 detection performance of the sensors can be improved by using the constructed metal–metal oxide-porous frame materials. [ABSTRACT FROM AUTHOR]

We employed the oxidative dehydrogenation of C 2 H 2 by CO 2 and the C 2 H 2 decomposition to prepare carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The use of a small amount of Ni catalyst made it possible to produce CNTs and CNFs having a highly defective structure at a relatively low temperature compared to the one typically used for the CNT synthesis. The synthesized CNTs and CNFs were decorated with about 10 nm-gold nanoparticles (AuNPs) via an electrostatic self-attachment. The electrode with CNTs synthesized via the C 2 H 2 –CO 2 reaction exhibits superior electrochemical reactivity with H 2 O 2 when compared to the ones with CNTs synthesized via C 2 H 2 decomposition, commercial CNTs, CNFs, and other more common carbon supports e.g. carbon black and activated charcoal. It demonstrates a rapid response, high sensitivity (104.9 μA mM−1 cm−2), wide linear working range (5 μM–23 mM), low detection limit (0.138 μM), good selectivity, reproducibility, and stability. The CNTs synthesized via the C 2 H 2 –CO 2 reaction are suggested as energy-saving, cost-effective and environmentally friendly supporting material candidates for practical applications. The electrodes with CNTs show a high electrochemically active surface area, low charge transfer resistance and fast mass transfer at the electrode surface that are key factors for H 2 O 2 detection. Image 1 [ABSTRACT FROM AUTHOR]

• Bimetallic Mo 1-x W x S 2 identifies composition-dependent H 2 O 2 sensing associated with intermediate bindings. • The optimal Mo 0.75 W 0.25 S 2 accomplishes outstanding performance in H 2 O 2 sensing. • The Mo 0.75 W 0.25 S 2 distinguishes cancer cells via monitoring endogenous H 2 O 2. Two-dimensional transition-metal dichalcogenides can serve as emerging biosensing platforms after rational structural optimization. Herein, we develop a series of Mo 1-x W x S 2 and investigate the composition-dependent sensing of hydrogen peroxide (H 2 O 2). Among them, the Mo 0.75 W 0.25 S 2 affords high sensitivity (1290 μA mM−1 cm−2), good selectivity, and wide applicable concentration range (4 × 10−1–1.0 × 104 μM). As indicated by theoretical investigations, such prominent performance stems from the bimetallic electronic configurations and the enhanced *OH binding on surface. Moreover, the Mo 0.75 W 0.25 S 2 is capable of monitoring trace amounts of H 2 O 2 released from normal cells and various cancer cells, which provides efficient cell detection for clinical diagnosis. In addition, the composition-dependence, as a result of electronic modulation on Mo 1-x W x S 2 surface, is further evidenced on electrocatalytic hydrogen evolution reaction, which highlights the promise in sensing and electrocatalysis that share similar electrochemical fundamentals. [ABSTRACT FROM AUTHOR]

Abstract Introducing Pt-based bimetallic nanocrystals into biosensors as a modifying agent has aroused immense interests to develop advanced non-enzymatic sensors for detecting H 2 O 2. In this study, Pt-Cu alloy octahedra with controlled compositions are prepared through a facile method serving as a modifying agent in biosensors for H 2 O 2 detection. The formation of Pt-Cu octahedra is achieved by simultaneous reduction of H 2 PtCl 6 and CuCl 2 by using N, N-dimethylformamide without addition of any other capping agents. A key to the synthesis of Pt-Cu octahedra is the introduction of Cl− ions, which can act as a dynamic template to facilitate the preferential overgrowth and accelerate the overall reduction kinetics. Compare to commercial Pt/C and spherical Pt-Cu nanoparticles, the Pt-Cu octahedra modified biosensors show substantially enhanced activity towards H 2 O 2 detection due to the unique synergetic effect between Pt and Cu and surface structure. Specifically, the electrode modified by Pt 55 Cu 45 octahedra achieves the highest sensitivity and best selectivity in neutral solution with a detection limit of 0.17 μM. Highlights • Pt-Cu alloy octahedra were synthesized by introduction of Cl− ions as a dynamic template. • Pt-Cu alloy octahedra showed high catalytic activity and good reliability for H 2 O 2 detection. • Synergetic effect and unique surface structure were two main reasons for enhancing the H 2 O 2 detection activity. [ABSTRACT FROM AUTHOR]

Highly sensitive, selective, and stable hydrogen peroxide (H2O2) detection using nanozyme-based catalysts are desirable for practical applications. Herein, vertical α-FeOOH nanowires were successfully grown on the surface of carbon fiber paper (CFP) via a low-temperature hydrothermal procedure. The formation of vertical α-FeOOH nanowires is ascribed to the structure-directing role of sodium dodecyl sulfate. The resulting free-standing electrode with one-dimensional (1D) nanowires offers oriented channels for fast charge transfer, excellent electrical contact between the electrocatalyst and the current collector, and good mechanical stability and reproducibility. Thus, it can serve as an efficient electrocatalyst for the reduction and sensitive detection of H2O2. The relation of the oxidation current of H2O2 with the concentration is linear from 0.05 to 0.5 mM with a sensitivity of -0.194 mA/(mM·Lcm2) and a low detection limit of 18 μM. Furthermore, the portability in the geometric tailor and easy device fabrication allow extending the general applicability of this free-standing electrode to chemical and biological sensors. [ABSTRACT FROM AUTHOR]

Dumbbell-like PtxPd100–x–Fe3O4 nanoparticles (NPs) were synthesized and studied for electrocatalytic reduction and sensing of H2O2. In 0.1 M phosphate buffered saline (PBS) solution, the 4–10 nm PtxPd100–x–Fe3O4 NPs showed the Pt/Pd composition-dependent catalysis with Pt48Pd52–Fe3O4 NPs having the best activity. The Pt48Pd52–Fe3O4 NPs were tested for H2O2 detection, and their H2O2 detection limit reached 5 nM, which was suitable for monitoring H2O2 generated from Raw 264.7 cells. These dumbbell-like PtPd–Fe3O4 NPs are the most sensitive probe ever reported and can be used to achieve real-time quantitative detection of H2O2 in biological environment for biological and biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we report on the electrocatalytic behaviour of a polypyrrole/magnetite hybrid electrode towards the reduction of hydrogen peroxide. The electrocatalytic activity of the composite electrode was demonstrated by cyclic voltammetric and chrono-amperometric measurements in comparison with the identically prepared neat polymer film. The stationary reduction currents, measured at an appropriately chosen potential (here at E =−0.3V), plotted against the peroxide concentration gave a perfect linear correlation in nitrogen atmosphere in the micromolar concentration range. The performance of the composite electrode was not affected by the presence of sulphate, nitrate or chloride anions. In the presence of dissolved oxygen a complex electrocatalytic activity was observed, involving the reduction of both oxygen and H2O2. However, a linear dependence was found also in oxygen containing media, although with much higher currents, but with the same slope (even at different oxygen concentrations). This fact may trigger the development of such hybrid electrodes towards hydrogen peroxide sensors in different aqueous (including natural) samples. [Copyright &y& Elsevier]

Abstract: Nanoporous gold (NPG) fabricated by dealloying Au–Ag film was investigated for the non-enzymatic detection of H2O2. The apparent activation energy of H2O2 electrochemical reduction on NPG was found to be as low as ∼30kJmol−1. The reduction currents at −0.4V vs. SCE demonstrated a strict linear dependence in a wide H2O2 concentration region from 10μM to 8mM with a detection limit 3.26μM. Furthermore, the biosensor based on NPG exhibited high selectivity, good reproducibility, and long-term stability. These results indicate that NPG could be a promising electrochemical material for H2O2 detection. [Copyright &y& Elsevier]

Abstract: Here we report the derivatization of mesoporous TiO2 thin films for the preparation of H2O2 amperometric sensors. The coordination of the bifunctional ligand 1,10 phenantroline, 5,6 dione on the surface Ti(IV) ions provides open coordination sites for Fe(II) cations which are the starting point for the growth of a layer of Prussian blue polymer. The porous structure of the mesoporous TiO2 allows the growth, ion by ion of the coordination polymer. Up to four layer of Prussian blue can be deposit without losing the porous structure of the film, which results in an enhanced response of these materials as H2O2 sensors. These porous confined PB modified electrodes are robust sensors that exhibit good reproducibility, environmental stability and high sensitivity towards H2O2 detection. [ABSTRACT FROM AUTHOR]