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Here, we demonstrate a new electrochemical sensing mechanism of ammonium ions (NH4+) involving a two-electron oxygen reduction reaction (ORR) and a hydrazine reaction. The NH4+ are electrooxidized to hydrazine by H2O2 derived from the ORR over a self-supporting Ag/TiO2 nanotube array composite electrode modified by hematite (Ag/Fe2O3/TNTs). The Ag/Fe2O3/TNT sensor exhibits a high sensitivity of 1876 µA mM−1 cm−2 with a detection limit of 0.18 µM under non-alkaline conditions, a short response time of 3 s, good reproducibility, and fine selectivity among various interferents, and is also successfully used in real water bodies to display high accuracy. Furthermore, this new mechanism has a certain universality in a range of Ag (main catalyst)/transition metal oxide (cocatalyst)/TNT sensing systems. This work offers a new design basis for the urgently needed electrochemical ammonia nitrogen sensors. [ABSTRACT FROM AUTHOR]

Conduction layer plays an important role in ion‐selective electrodes (ISEs) with solid‐state transduction. Herein, a lead ISE was prepared with Ti3C2 as the conductive layer, which has less water film and good anti‐interference ability to O2, CO2 and light. Concentration of lead ions can be quickly determined by detecting the electromotive force of the galvanic cell. In 10−3–10−7 M, the Nernst slope is found to be 28.3±1.02 mV/decade. And the detection limit is 4.4×10−8 M (n=3). It indicates that Ti3C2 is suitable for the conductive layer in solid ISEs. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline antimony trisulfide (Sb2S3) was successfully synthesized via microwave irradiation by the reaction of antimony trichloride (SbCl3) and thiourea (CS(NH2)2) with PVP as the surfactant. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). XRD results show that the as-prepared sample is orthorhombic-phase Sb2S3. TEM image of the as-prepared Sb2S3 shows the rod-like structure. HRTEM image indicates that rodbundles of Sb2S3 consists of a number nanorods with the diameter ranging from 30nm to 50nm. Detailed HRTEM image demonstrates the preferential direction growth of the Sb2S3 nanorods. The electrochemical properties of Sb2S3 were primarily investigated by constant current charge/discharge cycling tests in lithium hexafluorophosphate (LiPF6) solution. The possible electrochemical reaction mechanism was explained. The results indicate that the nanocrystalline Sb2S3 shows potential application in the field of the electrode materials. [Copyright &y& Elsevier]

Abstract: Cuprous oxide (Cu2O) nanoparticles of 35nm in crystal size have been successfully synthesized via electrochemical method in alkali NaCl solutions with copper as electrodes and K2Cr2O7 as additive. Photocatalytic degradation of methyl orange (MeO) in aqueous Cu2O solution was investigated under either ultraviolet (UV) light or sunlight. X-ray diffraction (XRD), transmission electron microscopy (SEM), Fourier transformation infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis) and X-ray photoelectron spectroscopy (XPS) were introduced to characterize the samples. The results indicate that electric current shows no obvious effect on the growth of Cu2O nanocrystals and that 97% of MeO can be decolorized under UV irradiation for 2h or under sunlight for 3h when amount of Cu2O is 2g/L. Recycling use of the catalyst revealed that Cu2O still has a high photocatalytic efficiency when repeatedly used for four times. Cu2O nanoparticles still kept its cubic crystal phase, but fractionally oxidized to be CuO after the photocatalysis. Compared with the original Cu2O nanoparticles, there has 1eV shift of Cu 2p electron and 1.6eV shift of Cu Auger signals for the Cu2O powders after four times photocatalysis. Some new peaks can also be observed at 401.1, 237.4 and 170.2eV in the Cu2O powders after photocatalysis. [Copyright &y& Elsevier]

Abstract A clay-modified electrode, sepiolite modified by TiO 2 nanoparticles (1–10 nm) incorporation of Cu 2 O particles (70–300 nm), was prepared for electrocatalytic reduction of H 2 O 2. The morphology, structure and properties of obtained materials were characterized by XRD, BET, FT-IR, SEM and TEM and the performance of the modified electrode was evaluated by cyclic voltammetry and chronoamperometry. The results revealed that the concentration of H 2 O 2 was proportional to the response to the current with the linear range from 20 μM to 2.36 mM and the detection limit of 10.2 μM under the working voltage. Compared with previous H 2 O 2 sensors, the Cu 2 O/TiO 2 /sepiolite electrode possess favorable electrochemical performance can be attributed to its large specific surface area and structure of TiO 2 -modified sepiolite in favour of load of Cu 2 O. Graphical abstract Unlabelled Image Highlights • Cu 2 O/TiO 2 -modified sepiolite as a clay-modified electrode was successfully prepared. • The modified electrode used for electrocatalytic reduction of H 2 O 2 presents a good sensing property. • The structure of TiO 2 -modified sepiolite in favour of load of Cu 2 O is the main factor in property enhancement. [ABSTRACT FROM AUTHOR]

Transition metal phosphides are promising candidates for alkaline hydrogen evolution reaction (HER), but the activation of H 2 O molecule is deficient. We adopt an interface engineering strategy to synthesize a hierarchical FeNiP/MoO x integrated electrode with multi-interface grown on monocrystalline NiMoO 4 nanorods. Such catalyst exhibits remarkable alkaline HER performance with a low overpotential of 97 mV at the current density of 100 mA cm−2 and sustainable durability over 20 h. Experimental and theoretical results reveal that interfaces among Fe 2 P, Ni 5 P 4 , and MoO x can efficiently activate H 2 O molecules and facilitate H desorption. Moreover, employing FeNiP/MoO x /NiMoO 4 /NF as a cathode, the cell voltage as low as 1.62 V to achieve a current density of 100 mA cm−2, with admirable durability over 20 h for alkaline water splitting (1.0 M NaOH + 0.5 M NaCl). This work offers a new avenue to rationally design a 3D robust, cost-effective catalyst with multi-interface for large-scale practical hydrogen production. [Display omitted] • Self-supported FeNiP/MoOx integrated electrode with multi-interface is synthesized on 3D monocrystalline NiMoO4 nanorods. • Coupling MoOx can efficiently modulate the electronic structure of metal phosphide. • Hierarchical interfaces of FeNiP/MoOx/NiMoO4/NF can efficiently activate H2O molecules and facilitate the H desorption. • FeNiP/MoOx/NiMoO4/NF as a cathode exhibits highly efficient overall alkaline seawater splitting activity and durability. [ABSTRACT FROM AUTHOR]