Ternary Composite of Hemin, Gold Nanoparticles and Graphene for Highly Efficient Decomposition of Hydrogen Peroxide

National Basic Research 973 Project [2014CB932004]; National Natural Science Foundation of China [31371005, 81171453]; Knowledge Innovation Program of Shenzhen City [JCYJ20130327150937484]; Fundamental Research Funds for the Central Universities; Program for New Century Excellent Talents in University; Ministry of Education; State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of SciencesA ternary composite of hemin, gold nanoparticles and graphene is prepared by a two-step process. Firstly, graphene-hemin composite is synthesized through pi-pi interaction and then hydrogen tetracholoroauric acid is reduced in situ by ascorbic acid. This ternary composite shows a higher catalytic activity for decomposition of hydrogen peroxide than that of three components alone or the mixture of three components. The Michaelis constant of this composite is 5.82 times lower and the maximal reaction velocity is 1.81 times higher than those of horseradish peroxidase, respectively. This composite also shows lower apparent activation energy than that of other catalysts. The excellently catalytic performance could be attributed to the fast electron transfer on the surface of graphene and the synergistic interaction of three components, which is further confirmed by electrochemical characterization. The ternary composite has been used to determine hydrogen peroxide in three real water samples with satisfactory results

High peroxidase catalytic activity of exfoliated few-layer graphene

Natural Science Foundation of China [81171453]; Fundamental Research Funds for the Central Universities; Program for New Century Excellent Talents in University; Ministry of Education; Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of SciencesFew-layer graphene prepared from graphite exfoliated by chitosan has a preserved structure without oxidation or destruction of the sp(2) character of the carbon plane and exhibits a higher peroxidase catalytic activity than that of graphene oxide (GO) and its reduced form. The peroxidase catalytic activity of as-obtained few-layer graphene is 45 times higher than that of GO and 4 times higher than that of reduced GO with the same concentration of 30 mu g mL(-1) and the detection limit of hydrogen peroxide is 10 nM. The excellently catalytic performance can be attributed to the fast electron transfer on the surface of few-layer graphene, which is further confirmed by electrochemical characterization. The as-prepared few-layer graphene has been used to determine hydrogen peroxide in three real water samples with satisfactory results. (c) 2013 Elsevier Ltd. All rights reserved

Self-cleaning BiOBr/Ag photocatalytic membrane for membrane regeneration under visible light in membrane distillation

In this study, an innovative electrospun photocatalyst self-cleaning BiOBr/Ag membrane is introduced for the MD treatment of dyeing wastewater coupled with post-MD UV and visible light exposure for fouled membrane regeneration. The E-BiOBr/Ag membrane was fabricated by successfully coating an electrospun membrane with BiOBr/Ag catalyst particles using electrospray technology, with the goal to achieve higher hydrophobicity and the reproducible property. Along with the E-BiOBr/Ag membrane, two commercial polyvinylidene difluoride (PVDF) and polytetrafluoroethylene (PTFE) membranes were tested for comparison. The fouling processes on all three membranes were monitored in real-time using optical coherence tomography (OCT). The coating of BiOBr/Ag particles on the E-BiOBr/Ag membrane\u27s surface accelerated dye foulant degradation through the electron-holes’ strong oxidization capacity when exposed to UV. Meanwhile, after Ag nanoparticles were coated on the BiOBr photocatalyst by UV deposition method, not only improved the efficiency of electron separation and transfer but also lessened the electron recombination phenomenon effectively. Correspondingly, compared to the two commercial membranes, the BiOBr/Ag photocatalyst membrane achieved significant improvements in the recovery efficiencies of the water contact angle (95.6%) and water flux (92.2%) under UV illumination, pointing to its potential for fouled membrane regeneration. In addition, the deposition of Ag on BiOBr as cocatalyst enhanced the visible light harvesting. Finally, the BiOBr/Ag photocatalyst membrane maintained good flux recovery and dye rejection (99.9%) over a 5-cycle MD test coupled with visible light exposure, suggesting the application of the novel self-cleaning photocatalyst membrane as a potential alternative for upscaling MD technology to the industrial level

Evaluation of road performance and micro-mechanism analysis of bentonite plastic concrete subgrade

This study evaluated the performance of bentonite plasticized concrete with good deformation coordination as a road base material, to address the poor deformation coordination of rigid base layers in roads. Through tests such as slump, strength, permeability, and scanning electron microscopy (SEM) and x-ray diffraction (XRD), the study analyzed the variations in workability, mechanical properties, and durability of plastic concrete as a base material under different bentonite and cement contents, as well as the underlying micro-mechanisms. The results showed that plastic concrete exhibited good workability, which improved with increased bentonite and cement content. The 28-day mechanical properties of the plastic concrete met the design criteria for road base layers and had features of higher load-bearing capacity, good toughness, slow strength attenuation, and overall integrity. In durability, the increase of bentonite content enhanced the concrete’s permeability, but decreased abrasivenes and shrinkage. From economic, performance, and engineering perspectives, the optimal bentonite and cement contents for the plastic concrete base were in the ranges of 90 kg m ^−3 to 120 kg m ^−3 and 110 kg m ^−3 to 150 kg m ^−3 , respectively

Solvothermal synthesis of copper-doped BiOBr microflowers with enhanced adsorption and visible-light driven photocatalytic degradation of norfloxacin

© 2020 Elsevier B.V. Photocatalysts based on copper-doped bismuth oxybromide (Cu-doped BiOBr) were synthesised using a solvothermal method and assessed for their ability to degrade norfloxacin under visible light. The Cu atoms were successfully doped into the crystal lattice of BiOBr, yielding Cu-doped BiOBr microflowers with a morphology and crystal structure identical to that of pristine BiOBr. The as-prepared Cu-doped BiOBr showed activity superior to BiOBr in the photocatalytic degradation of norfloxacin under visible-light irradiation, which was attributed to its improved light-harvesting properties, enhanced charge separation and interfacial charge transfer. Furthermore, we found for the first time that the introduction of Cu into BiOBr enhanced the adsorption capacity between the photocatalyst and norfloxacin, which we considered to be the main contribution to its improved performance. Cu-doped BiOBr containing the optimal proportion of Cu and Bi (Cu:Bi = 0.03) had a photocatalytic degradation constant of 0.64 ×10−2 min−1, which is 2.28 times higher than that of undoped BiOBr. The primary oxidation pathway was determined to involve the transfer of photogenerated holes to norfloxacin. Finally, we demonstrated that the Cu-doped BiOBr photocatalyst retained 95% of its initial activity even after five successive catalytic cycles, confirming its recyclability