Search

The strong adsorption of the exsolved A-site of SrCoO2.52 (SC) perovskite with peroxymonosulfate (PMS) makes the effective activation of PMS challenging. A surface reconstruction strategy has been applied to enhance direct electron transfer from the active B-site to PMS. Thus, an interface architecture of Co3O4 nanoparticles in situ growing on the SC perovskite [SrCoO3−δ@Co3O4 (SCC-2)] was developed, which exhibited enhanced catalytic activity. It was found that the surface reconstruction process not only transferred the adsorption site of PMS from the Sr to the Co site, but also enhanced the electron transfer ability of SCC-2. The formed Co–O metal–oxygen bridge facilitated the electron transfer from the bulk SrCoO3−δ to the Co sites of surface Co3O4, thus enhancing the Co2+/Co3+ redox cycle. Compared with pristine SC, the PMS activation improved by 13.1%, and ENR degradation boosted by 1.23 times for SCC-2. This study can provide guidelines to design superior catalysts by surface reconstruction. [ABSTRACT FROM AUTHOR]

Constructing low cost and efficient electrochemical sensors for highly sensitive detection of hydrazine has a great significance in the field of environmental monitoring and protection. Herein, metal–organic framework derived Co3S4 nanosheets grown on Ti mesh (Co3S4/TM) were successfully synthesized by employing a facile anion exchange reaction and hydrothermal vulcanization with Co-MOF as the precursor. The crystalline structure and morphology of as-synthesized samples were characterized by XRD, SEM, Raman, XPS and TEM analysis. It was found that Co3S4 nanosheets were stacked loosely and irregularly on each other to form a three-dimensional (3D) porous structure. The electrochemical sensing performance of Co3S4/TM toward hydrazine was investigated in 0.1 M NaOH solution. The results showed that Co3S4/TM presented a better electrocatalytic activity toward hydrazine oxidation than Co-MOF/TM and Co(OH)2/TM, owing to the high electrical conductivity of Co3S4 for enhancing electron transfer and the 3D porous structure for providing many more accessible active sites and shortening ion diffusion length as well as promoting mass transfer for hydrazine electrooxidation. As a result, Co3S4/TM exhibited a superior analytical performance with a wide linear range of 0.005–2.0 mM, a high sensitivity of 2956 μA mM−1 cm−2 and a low detection limit of 0.7 μM (S/N = 3), which was superior or comparable to that of the recently reported sensor. Because of the good selectivity and reproducibility, Co3S4/TM was applied to detection of hydrazine in tap water and it showed good recovery, indicating that it could be a promising candidate for analyzing hydrazine in practical application. [ABSTRACT FROM AUTHOR]

Exploiting cost-effective, highly efficient and stable alkaline electrocatalysts is a great challenge for the hydrogen evolution reaction (HER). Herein, NiMoO4 and CoFe layered double hydroxide (CoFe LDH) with poor crystallinity were successively deposited on Cu nanowire (Cu NW) grown on Cu foam by a two-step electrodeposition process, which was verified by XRD, Raman, ATR-FTIR, XPS, SEM, TEM and HRTEM characterizations. The HER performance measurement in 1.0 M KOH solution showed the optimal CoFe LDH-60 s/NiMoO4/Cu NW/Cu foam sample demonstrated prominent alkaline HER activity and long-term durability with an ultralow overpotential of 45 mV at −10 mA cm−2 and a Tafel slope of 94.0 mV dec−1, superior to the recently reported transition metal-based electrocatalysts. Further study clarified that the remarkable alkaline HER performance could be attributed to the strong synergistic effect between CoFe LDH-60 s and NiMoO4 in favor of water adsorption/activation and optimizing hydrogen adsorption, and providing plentiful exposed active sites as well as an enhanced electron transfer process offered by the unique 1D nanostructure with Cu nanowire as the core. This work can provide a guidance for designing a highly active and stable electrocatalyst for hydrogen production. [ABSTRACT FROM AUTHOR]

The selective crystal facet growth of BiOX (X = Cl, Br, I) is very significant since each facet possesses different physicochemical properties. In this study, polyvinylpyrrolidone (PVP), a structure directing agent, was unprecedentedly introduced to modulate the crystal facet growth of BiOX to obtain BiOX/PVP with more (110) active facet exposure, for the first time. The exposure of the (110) crystal surface of BiOX due to the introduction of PVP is comprehensively explained at the molecular level. A possible application is the photodegradation of dyes, such as rhodamine B (RhB), from wastewater as more superoxide radicals are generated compared to the pure BiOX sample under identical visible light irradiation conditions. According to first-principles calculations, the (110) crystal face has a higher electron density, allowing it to generate free electrons more easily. In comparison with pure BiOCl, a higher (110) active facet exposure for BiOCl/PVP prolonged the lifetimes of photoinduced carries and enhanced the photocatalytic activity. Herein, the enhancement mechanism of photoactivity was explained via various experiments and theoretical calculations in detail. [ABSTRACT FROM AUTHOR]

We synthesized a flower-like Ni–Mn–S structure on Ti mesh (Ni–Mn–S/TM) as a monolithic sensing platform by a facile electrodeposition method. The phase composition and surface morphology of the as-prepared samples were characterized by XRD, XPS, SEM, TEM and HRTEM. The electrodeposits displayed a unique hierarchical nanosheet structure. Mn incorporation remarkably modulated the surface morphology of Ni–S on TM. This flower-like structure could increase the active surface area, providing more active sites for the electrocatalytic reaction. Electrochemical measurement demonstrated that Ni–Mn–S/TM exhibited good response to glucose in the range of 12 μM to 3.5 mM with a high sensitivity of 860.8 μA mM−1 cm−2. The binder-free Ni–Mn–S/TM electrode also presented good anti-interference ability, reusability and stability. This work gives a new avenue to improve the glucose sensing performance of nickel sulfide and even other nanomaterials. [ABSTRACT FROM AUTHOR]

Three-dimensional interconnected Co(OH)2 nanosheets (Co(OH)2 NS) were electrodeposited onto a Ti mesh (TM) surface, which was demonstrated by XRD, Raman spectroscopy, XPS and SEM characterization. The electrochemical sensing performance of the Co(OH)2 NS/TM toward hydrazine was investigated by cyclic voltammetry and amperometric techniques in a 0.1 M NaOH aqueous solution. The as-prepared Co(OH)2 NS/TM with an electrodeposition time of 10 min exhibited prominent capacity to detect hydrazine with a wide linear range from 5 μM to 3.0 mM and limit of detection (LOD) of 1.98 μM. Co(OH)2 NS/TM electrodes also showed a high sensitivity of 2793.9 μA mM−1 cm−2, excellent selectivity, reproducibility, appreciable stability with a RSD less than 3.5%, as well as the high recovery of hydrazine in real samples, indicating its potential application in real sample analysis. [ABSTRACT FROM AUTHOR]

The magnetic composite BiOCl-SrFe12O19, a novel p-n type heterojunction was synthesized by hydrolysis with a medium temperature sintering method. The microstructure and magnetic properties of the prepared material were characterized by FTIR, XRD, SEM, TEM, HRTEM, SAED, and VSM. The results showed the [001] facet of BiOCl with high photocatalytic activity was exposed in the BiOCl-SrFe12O19. The heterostructured BiOCl-SrFe12O19 had better magnetic properties, contributing to its reuse and improvement in photocatalysis. Moreover, the composite was blessed with excellent photocatalytic activity and stability. In the BiOCl-SrFe12O19 system, SrFe12O19 not only inhibited the growth of BiOCl along the [001] direction to enhance the exposure of the [001] wafer, but also acted as a sensitizer absorbing light irradiation. The magnetic field generated from SrFe12O19 made BiOCl, under light irradiation, produce more photo-induced electrons and holes and simultaneously hampered their recombination. For the first time we propose the possible mechanism of how to enhance photocatalytic activity by a magnetic field effect originating from the magnetic photocatalyst itself.