Doped MXenes—A new paradigm in 2D systems: Synthesis, properties and applications

Since 2011, 2D transition metal carbides, carbonitrides and nitrides known as MXenes have gained huge attention due to their attractive chemical and electronic properties. The diverse functionalities of MXenes make them a promising candidate for multitude of applications. Recently, doping MXene with metallic and non-metallic elements has emerged as an exciting new approach to endow new properties to this 2D systems, opening a new paradigm of theoretical and experimental studies. In this review, we present a comprehensive overview on the recent progress in this emerging field of doped MXenes. We compare the different doping strategies; techniques used for their characterization and discuss the enhanced properties. The distinct advantages of doping in applications such as electrocatalysis, energy storage, photovoltaics, electronics, photonics, environmental remediation, sensors, and biomedical applications is elaborated. Additionally, theoretical developments in the field of electrocatalysis, energy storage, photovoltaics, and electronics are explored to provide key specific advantages of doping along with the underlying mechanisms. Lastly, we present the advantages and challenges of doped MXenes to take this thriving field forward

Graphene Oxides in Water: Characterization, Reactivity, and Application

Recently discovered, graphene and graphene oxide materials have drawn considerable research attention due to outstanding and novel properties, which underpin wide material potential for a number of advanced applications including supercapacitors, solar cells, sensors, catalysts, semiconductors, sorbents, and membranes, among others. Graphene oxides (GO), which are considered as a family of oxidized graphene materials (derivatives), is a key precursor to the synthesis of free-standing graphene via oxidation-exfoliation-reduction pathways. GO properties depend on the synthesis routes/conditions (i.e. derivatization), including partially maintaining graphene (i.e. sp2) properties. Further, oxygen-containing functionalities (epoxy, hydroxyl, carbonyl, and carboxyl groups) render GO hydrophilic – and correspondingly stability in water, thus underpinning (aqueous-based) transport and even reactivity. Juxtaposed with aforementioned application potential, the inadvertent implications of GO, and corresponding daughter products, in environmental systems remain largely unknown. For successful aqueous applications, it is necessary to overcome two fundamental challenges: 1) control of the functional group quantity/type via synthesis process, and 2) understand the behavior (e.g. fate and transport, application) of the material(s) as a function of surface chemistry and reactivity. In this work, classic graphene oxide synthesis is systematically explored and evaluated, including synthesis temperature, reaction time, oxidant ratios, and sonication time, with resulting material properties described, For this matrix, materials are characterized with regard to aqueous stability and spectral analyses including transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermogravimetric analysis (TGA), total organic carbon analysis (TOC), and Fourier transform infrared spectroscopy (FTIR). Additionally, the reactivity and transformation of these materials in the presence of free chlorine, a common oxidant, under light irradiation is also described. Specifically, reaction kinetics and mechanism(s) are systematically evaluated as a function of pH, dissolved oxygen, and initial size of graphene oxide (coupons). For these reactions, partially mineralization is confirmed via direct CO2 detection and carbon mass balance. Final product(s) are described via TEM, FTIR, XPS, Raman spectroscopy, and mass spectrometry (MS). Further, we evaluated and describe graphene oxide applications, including as a platform sorbent for rare earth metals, focusing on cerium(III) and lanthanum(III). For these, graphene oxide functionality (both function group type and quantity), solution pH, and ionic strength are systematically evaluated and described towards sorption optimization. Lastly, graphene oxide membranes are explored with regard to surface reactivity (i.e. exposure to free chlorine), under both dark and light irradiation conditions, as it relates membrane stability and (separation) performance for related water treatment processes

MoS2 and MoS2 Nanocomposites for Adsorption and Photodegradation of Water Pollutants: A Review

The need for fresh and conveniently treated water has become a major concern in recent years. Molybdenum disulfide (MoS2) nanomaterials are attracting attention in various fields, such as energy, hydrogen production, and water decontamination. This review provides an overview of the recent developments in MoS2-based nanomaterials for water treatment via adsorption and photodegradation. Primary attention is given to the structure, properties, and major methods for the synthesis and modification of MoS2, aiming for efficient water-contaminant removal. The combination of MoS2 with other components results in nanocomposites that can be separated easily or that present enhanced adsorptive and photocatalytic properties. The performance of these materials in the adsorption of heavy metal ions and organic contaminants, such as dyes and drugs, is reviewed. The review also summarizes current progress in the photocatalytic degradation of various water pollutants, using MoS2-based nanomaterials under UV-VIS light irradiation. MoS2-based materials showed good activity after several reuse cycles and in real water scenarios. Regarding the ecotoxicity of the MoS2, the number of studies is still limited, and more work is needed to effectively evaluate the risks of using this nanomaterial in water treatment.publishe

Biomedical waste management by using nanophotocatalysts: The need for new options

Biomedical waste management is getting significant consideration among treatment technologies, since insufficient management can cause danger to medicinal service specialists, patients, and their environmental conditions. The improvement of waste administration protocols, plans, and policies are surveyed, despite setting up training programs on legitimate waste administration for all healthcare service staff. Most biomedical waste substances do not degrade in the environment, and may also not be thoroughly removed through treatment processes. Therefore, the long-lasting persistence of biomedical waste can effectively have adverse impact on wildlife and human beings, as well. Hence, photocatalysis is gaining increasing attention for eradication of pollutants and for improving the safety and clearness of the environment due to its great potential as a green and eco-friendly process. In this regard, nanostructured photocatalysts, in contrast to their regular counterparts, exhibit significant attributes such as non-toxicity, low cost and higher absorption efficiency in a wider range of the solar spectrum, making them the best candidate to employ for photodegradation. Due to these unique properties of nanophotocatalysts for biomedical waste management, we aim to critically evaluate various aspects of these materials in the present review and highlight their importance in healthcare service settings

Sustainable Biomaterials: Current Trends, Challenges and Applications

Biomaterials and sustainable resources are two complementary terms supporting the development of new sustainable emerging processes. In this context, many interdisciplinary approaches including biomass waste valorization and proper usage of green technologies, etc., were brought forward to tackle future challenges pertaining to declining fossil resources, energy conservation, and related environmental issues. The implementation of these approaches impels its potential effect on the economy of particular countries and also reduces unnecessary overburden on the environment. This contribution aims to provide an overview of some of the most recent trends, challenges, and applications in the field of biomaterials derived from sustainable resource

Doped MXenes—A new paradigm in 2D systems: Synthesis, properties and applications

Since 2011, 2D transition metal carbides, carbonitrides and nitrides known as MXenes have gained huge attention due to their attractive chemical and electronic properties. The diverse functionalities of MXenes make them a promising candidate for multitude of applications. Recently, doping MXene with metallic and non-metallic elements has emerged as an exciting new approach to endow new properties to this 2D systems, opening a new paradigm of theoretical and experimental studies. In this review, we present a comprehensive overview on the recent progress in this emerging field of doped MXenes. We compare the different doping strategies; techniques used for their characterization and discuss the enhanced properties. The distinct advantages of doping in applications such as electrocatalysis, energy storage, photovoltaics, electronics, photonics, environmental remediation, sensors, and biomedical applications is elaborated. Additionally, theoretical developments in the field of electrocatalysis, energy storage, photovoltaics, and electronics are explored to provide key specific advantages of doping along with the underlying mechanisms. Lastly, we present the advantages and challenges of doped MXenes to take this thriving field forward

New Trends in Beverage Packaging Systems: A Review

New trends in beverage packaging are focusing on the structure modification of packaging materials and the development of new active and/or intelligent systems, which can interact with the product or its environment, improving the conservation of beverages, such as wine, juice or beer, customer acceptability, and food security. In this paper, the main nutritional and organoleptic degradation processes of beverages, such as oxidative degradation or changes in the aromatic profiles, which influence their color and volatile composition are summarized. Finally, the description of the current situation of beverage packaging materials and new possible, emerging strategies to overcome some of the pending issues are discussed

Photocatalytic TiO2/porous BNNSs composites for textile dyeing wastewater treatment

This project develops a novel photocatalyst for the cleaning of textile dyeing wastewater. The newly-developed photocatalyst was prepared by combing porous boron nitride nanosheets with titanium dioxide particles and these composites show potentials for the practical treatment of the textile dyeing wastewater in a large scale

Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis

In recent years, the formulation of innovative photocatalysts activated by visible or solar light has been attracting increasing attention because of their notable potential for environmental remediation and use in organic synthesis reactions. Generally, the strategies for the development of visible-light-active photocatalysts are mainly focused on enhancing degradation efficiency (in the case of environmental remediation) or increasing selectivity toward the desired product (in the case of organic synthesis). These goals can be achieved by doping the semiconductor lattice with metal and/or non-metal elements in order to reduce band gap energy, thereby providing the semiconductor with the ability to absorb light at a wavelength higher than the UV range. Other interesting options are the formulation of different types of heterojunctions (to increase visible absorption properties and to reduce the recombination rate of charge carriers) and the development of innovative catalytic materials with semiconducting properties. This reprint is focused on visible-light-active photocatalysts for environmental remediation and organic synthesis, featuring the state of the art as well as advances in this field