High Activity and Selectivity of M-N/C Catalysts toward Two-Electron O2 Electroreduction

2022 ◽  
Author(s):  
Alex da Cunha Campos ◽  
Thiago Lopes
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Synthesis ◽  
High Activity ◽  
Large Scale ◽  
Reduction Process ◽  
Electrochemical Process ◽  
Ambient Conditions ◽  
Hydrogen Electrode ◽  
Hydrogen Peroxide Production ◽  
Diverse Range

Hydrogen Peroxide (H2O2) is a versatile and environmentally friendly chemical oxidant with a remarkably diverse range of applications, including fine chemical synthesis, first aid kits for disinfection, pulp and textile bleaching, wastewater treatment and others. Industrial production of H2O2 is based on the anthraquinone oxidation/reduction process, which consumes a lot of energy, requires complex and large-scale equipment, and mass extraction solvents, generating an enormous waste. There is a general demand for a more decentralised infrastructure, where energy conversion and chemical synthesis are conducted closer to the point of consumption. In this context, developing an electrochemical process to partially reduce O2 to H2O2 (O2 + 2H+/e- → H2O2) in an acidic medium would be an attractive strategy that could be carried out under ambient conditions using renewable energies. However, practical and economic electrocatalysts that exhibit high activity and selectivity for hydrogen peroxide production is to be developed. A series of M-N/C catalysts (M = Fe, Co, and Cu) were prepared in the present study. The performance (activity and selectivity) of these catalysts for the oxygen reduction reaction was investigated in the potential window of 0.2 V to 1.0 V vs. the Reversible Hydrogen Electrode (RHE). Electrochemical measurements demonstrated that the Co-N/C [c] electrocatalyst exhibits high ORR activity and exceptional selectivity for hydrogen peroxide production (92% at 0.5 V vs. RHE).

scholarly journals Selective electrochemical production of hydrogen peroxide at zigzag edges of exfoliated molybdenum telluride nanoflakes

2020 ◽  
Vol 7 (8) ◽  
pp. 1360-1366 ◽  
Author(s):  
Xuan Zhao ◽  
Yu Wang ◽  
Yunli Da ◽  
Xinxia Wang ◽  
Tingting Wang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
High Activity ◽  
Molecular Oxygen ◽  
Large Mass ◽  
Binding Energies ◽  
Hydrogen Electrode ◽  
Production Of Hydrogen ◽  
Activity Onset ◽  
Electrochemical Production ◽  
Electron Reduction

Abstract The two-electron reduction of molecular oxygen represents an effective strategy to enable the green, mild and on-demand synthesis of hydrogen peroxide. Its practical viability, however, hinges on the development of advanced electrocatalysts, preferably composed of non-precious elements, to selectively expedite this reaction, particularly in acidic medium. Our study here introduces 2H-MoTe2 for the first time as the efficient non-precious-metal-based electrocatalyst for the electrochemical production of hydrogen peroxide in acids. We show that exfoliated 2H-MoTe2 nanoflakes have high activity (onset overpotential ∼140 mV and large mass activity of 27 A g−1 at 0.4 V versus reversible hydrogen electrode), great selectivity (H2O2 percentage up to 93%) and decent stability in 0.5 M H2SO4. Theoretical simulations evidence that the high activity and selectivity of 2H-MoTe2 arise from the proper binding energies of HOO* and O* at its zigzag edges that jointly favor the two-electron reduction instead of the four-electron reduction of molecular oxygen.

Application of Sulfate Reduction for the Biological Conversion of Anglesite to Galena

2007 ◽  
Vol 20-21 ◽  
pp. 197-200 ◽  
Author(s):  
Anke Wolthoorn ◽  
Simon Kuitert ◽  
Henk Dijkman ◽  
Jacco L. Huisman
Keyword(s):  
Sulfate Reduction ◽  
Large Scale ◽  
Reduction Process ◽  
Electrochemical Process ◽  
Precipitation Process ◽  
Flotation Process ◽  
Bench Scale ◽  
Sulfate Reduction Process ◽  
Biological Sulfate Reduction ◽  
Ph Decrease

In a bench scale trial biological sulfate reduction was applied to convert anglesite (PbSO4) to galena (PbS). Anglesite is a main constituent of waste fractions such as the residue from an indirect leaching process or in lead paste from spent car batteries. The goal of this study was to develop a technology to decrease the lead (Pb) emissions by converting PbSO4 from a waste fraction into PbS, which can be recovered from the waste fraction using a flotation process or an electrochemical process. The conversion of anglesite to galena is based on the biological sulfate reduction process and a metal precipitation process. First sulfate is biologically reduced to sulfide. Secondly, the Pb2+ from the PbSO4 reacts chemically with the sulfide resulting from the first reaction. A bench-scale reactor was started up using sulfate- and sulfur-containing influent. The reactor was seeded with biocatalyst from several full-scale reactors. Anglesite-containing residue was added batch-wise when the formation of sulfide started. The residue contained mainly PbSO4 (51.7%), sulfate (SO4 2-, 19.9%) and elemental sulfur (S0, 15.1%). Galena precipitates in the bioreactor due to the near-neutral pH at which sulfate reduction is carried out. During the experiment a surplus of sulfide relative to Pb was maintained to prevent the formation of PbCO3 and the accompanying pH decrease that would unavoidable result in the inhibition of the biocatalyst. Both sulfate and sulfur present in the residue were biologically reduced. The formation of PbS was confirmed by the increased Pb:O ratio of the sludge (1:0.03) relative to the Pb:O ratio of the residue (1:0.3). A potential large-scale application is proposed.

Xylenol-orange-assay-of-hydrogen-peroxide for Measuring Uricase Activity and Recognizing High-activity Uricase Mutant

2013 ◽  
Vol 19 (3) ◽  
pp. 523-527 ◽  
Author(s):  
Miaomiao LIU ◽  
Juan FENG ◽  
Hongbo LIU ◽  
Xiaolan YANG ◽  
Liping FENG ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
High Activity ◽  
Xylenol Orange ◽  
Uricase Activity

Building a Culture of Ethical, Comparable, Authentic Assessment

2019 ◽  
pp. 463-481
Author(s):  
Andrew Reid ◽  
Julie Ballantyne
Keyword(s):  
Teaching And Learning ◽  
Large Scale ◽  
Authentic Assessment ◽  
Subject Area ◽  
Music Educators ◽  
System Level ◽  
Diverse Range ◽  
Effective Learning ◽  
School Based ◽  
The Subject

In an ideal world, assessment should be synonymous with effective learning and reflect the intricacies of the subject area. It should also be aligned with the ideals of education: to provide equitable opportunities for all students to achieve and to allow both appropriate differentiation for varied contexts and students and comparability across various contexts and students. This challenge is made more difficult in circumstances in which the contexts are highly heterogeneous, for example in the state of Queensland, Australia. Assessment in music challenges schooling systems in unique ways because teaching and learning in music are often naturally differentiated and diverse, yet assessment often calls for standardization. While each student and teacher has individual, evolving musical pathways in life, the syllabus and the system require consistency and uniformity. The challenge, then, is to provide diverse, equitable, and quality opportunities for all children to learn and achieve to the best of their abilities. This chapter discusses the designing and implementation of large-scale curriculum as experienced in secondary schools in Queensland, Australia. The experiences detailed explore the possibilities offered through externally moderated school-based assessment. Also discussed is the centrality of system-level clarity of purpose, principles and processes, and the provision of supportive networks and mechanisms to foster autonomy for a diverse range of music educators and contexts. Implications for education systems that desire diversity, equity, and quality are discussed, and the conclusion provokes further conceptualization and action on behalf of students, teachers, and the subject area of music.

scholarly journals Rapid synchronized fabrication of vascularized thermosets and composites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mayank Garg ◽  
Jia En Aw ◽  
Xiang Zhang ◽  
Polette J. Centellas ◽  
Leon M. Dean ◽  
...  
Keyword(s):  
Large Scale ◽  
Capillary Flow ◽  
External Heat ◽  
Frontal Polymerization ◽  
Self Healing ◽  
Vascular Networks ◽  
Ambient Conditions ◽  
External Energy ◽  
Imaging Phantoms ◽  
Vascular Structures

AbstractBioinspired vascular networks transport heat and mass in hydrogels, microfluidic devices, self-healing and self-cooling structures, filters, and flow batteries. Lengthy, multistep fabrication processes involving solvents, external heat, and vacuum hinder large-scale application of vascular networks in structural materials. Here, we report the rapid (seconds to minutes), scalable, and synchronized fabrication of vascular thermosets and fiber-reinforced composites under ambient conditions. The exothermic frontal polymerization (FP) of a liquid or gelled resin facilitates coordinated depolymerization of an embedded sacrificial template to create host structures with high-fidelity interconnected microchannels. The chemical energy released during matrix polymerization eliminates the need for a sustained external heat source and greatly reduces external energy consumption for processing. Programming the rate of depolymerization of the sacrificial thermoplastic to match the kinetics of FP has the potential to significantly expedite the fabrication of vascular structures with extended lifetimes, microreactors, and imaging phantoms for understanding capillary flow in biological systems.

scholarly journals Kinetic resolution of indolines by asymmetric hydroxylamine formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gang Wang ◽  
Ran Lu ◽  
Chuangchuang He ◽  
Lei Liu
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Synthesis ◽  
Late Stage ◽  
Kinetic Resolution ◽  
High Efficiency ◽  
Bond Formation ◽  
Bioactive Molecules ◽  
Environmentally Benign ◽  
Secondary Amines

AbstractCatalytic kinetic resolution of amines represents a longstanding challenge in chemical synthesis. Here, we described a kinetic resolution of secondary amines through oxygenation to produce enantiopure hydroxylamines involving N–O bond formation. The economic and practical titanium-catalyzed asymmetric oxygenation with environmentally benign hydrogen peroxide as oxidant is applicable to a range of racemic indolines with multiple stereocenters and diverse substituent patterns in high efficiency with efficient chemoselectivity and enantio-discrimination. Late-stage asymmetric oxygenation of bioactive molecules that are otherwise difficult to synthesize was also explored.

Photoelectrochemical Hydrogen Peroxide Production from Water on a WO3/BiVO4Photoanode and from O2on an Au Cathode Without External Bias

2017 ◽  
Vol 12 (10) ◽  
pp. 1111-1119 ◽  
Author(s):  
Kojiro Fuku ◽  
Yuta Miyase ◽  
Yugo Miseki ◽  
Takashi Funaki ◽  
Takahiro Gunji ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Peroxide Production ◽  
External Bias
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