Graphene-based materials are gaining heightened attention as novel materials for environmental applications The unique physicochemical properties of graphene, notably its exceptionally high surface area, electron mobility, thermal conductivity, and mechanical strength, can lead to novel or improved technologies to address the pressing global environmental challenges This critical review assesses the recent developments in the use of graphene-based materials as sorbent or photocatalytic materials for environmental decontamination, as building blocks for next generation water treatment and desalination membranes, and as electrode materials for contaminant monitoring or removal The most promising areas of research are highlighted, with a discussion of the main challenges that we need to overcome in order to fully realize the exceptional properties of graphene in environmental applications

Environmental applications of graphene-based nanomaterials.

Carbon dioxide (CO2) capture using solid sorbents has been recognized as a very promising technology that has attracted intense attention from both academic and industrial fields in the last decade. It is astonishing that around 2000 papers have been published from 2011 to 2014 alone, which is less than three years after our first review paper in this journal on solid CO2 sorbents was published. In this short period, much progress has been made and the major research focus has more or less changed. Therefore, we feel that it is necessary to give a timely update on solid CO2 capture materials, although we still have to keep some important literature results published in the past years so as to keep the good continuity. We believe this work will benefit researchers working in both academic and industrial areas. In this paper, we still organize the CO2 sorbents according to their working temperatures by classifying them as such: (1) low-temperature ( 400 °C). Since the sorption capacity, kinetics, recycling stability and cost are important parameters when evaluating a sorbent, these features will be carefully considered and discussed. In addition, due to the huge amounts of cost-effective CO2 sorbents demanded and the importance of waste resources, solid CO2 sorbents prepared from waste resources and their performance are reviewed. Finally, the techno-economic assessments of various CO2 sorbents and technologies in real applications are briefly discussed.

Recent advances in solid sorbents for CO2 capture and new development trends

In recent years, heterogeneous photocatalysis has received much research interest because of its powerful potential applications in tackling many important energy and environmental challenges at a global level in an economically sustainable manner. Due to their unique optical, electrical, and physicochemical properties, various 2D graphene nanosheets-supported semiconductor composite photocatalysts have been widely constructed and applied in different photocatalytic fields. In this review, fundamental mechanisms of heterogeneous photocatalysis, including thermodynamic and kinetics requirements, are first systematically summarized. Then, the photocatalysis-related properties of graphene and its derivatives, and design rules and synthesis methods of graphene-based composites are highlighted. Importantly, different design strategies, including doping and sensitization of semiconductors by graphene, improving electrical conductivity of graphene, increasing eloectrocatalytic active sites on graphene, strengthening interface coupling between semiconductors and graphene, fabricating micro/nano architectures, constructing multi-junction nanocomposites, enhancing photostability of semiconductors, and utilizing the synergistic effect of various modification strategies, are thoroughly summarized. The important applications including photocatalytic pollutant degradation, H2 production, and CO2 reduction are also addressed. Through reviewing the significant advances on this topic, it may provide new opportunities for designing highly efficient 2D graphene-based photocatalysts for various applications in photocatalysis and other fields, such as solar cells, thermal catalysis, separation, and purification.

/pdf/graphene-in-photocatalysis-a-review-1oawvvl4tw.pdf

Graphene in Photocatalysis: A Review

Graphene oxide: A promising nanomaterial for energy and environmental applications

Synthesis and Applications

Layered double hydroxides (LDHs) show great potential as CO2 adsorbent materials, but require improvements in stability and CO2 adsorption capacity for commercial applications. In the current study, graphene oxide provides a light-weight, charge-complementary, two-dimensional (2D) material that interacts effectively with the 2D LDHs, in turn enhancing the CO2 uptake capacity and multicycle stability of the assembly. As a result, the absolute capacity of the LDH was increased by 62% using only 7 wt % graphene oxide (GO) as a support. The experimental procedure for the synthesis of the materials is based on a direct precipitation of the LDH nanoparticles onto GO followed by a structural and physical characterization by electron microscopy, X-ray diffraction, thermogravimetric analysis, and Brunauer-Emmett-Teller (BET) surface area measurements. Detailed titration confirmed the compatibility of the surface chemistry. After thermal decomposition, mixed metal oxides (MMOs) are obtained with the basic sites required for the CO2 adsorption. A range of samples with different proportions of GO/MMO were prepared, fully characterized, and correlated with the CO2 sorption capacity, established via TGA.

/pdf/graphene-oxide-as-support-for-layered-double-hydroxides-42wna983v3.pdf

M Asiri

Papers

Graphene Oxide as Support for Layered Double Hydroxides: Enhancing the CO2 Adsorption Capacity