Layered double hydroxides in catalyzing the green hydrogen revolution: advancements and prospects.

Epoxy/layered double hydroxide (LDH) nanocomposites: Synthesis, characterization, and Excellent cure feature of nitrate anion intercalated Zn-Al LDH

Recent development of layered double hydroxide-derived catalysts − Rehydration, reconstitution, and supporting, aiming at commercial application −

Construction of porous flower-like Ru-doped CoNiFe layered double hydroxide for supercapacitors and oxygen evolution reaction catalysts

The concept of green economy has received significant international attention over the past few years as a tool to address the 2008 financial crisis. Governments today are seeking effective ways to lead their nations out of the crisis and the green economy (in its various forms) has been proposed as a means for catalyzing renewed national policy development and international cooperation and support for sustainable development. The aim of this article is to define and highlight the importance of the green (blue) economy and compare it with the so-called greed economy. This article is divided into different sections: after a brief introduction is a systematic literature review; the second section is about sustainable development and the green economy concept; the third is about the green economy and blue economy concept; and the fourth compares greed economy to green (blue) economy. Finally, the author will draw conclusions.

Layered double hydroxides (LDHs, [M2+1−xM3+x(OH)2]x+(An−x/n)·mH2O), also known as hydrotalcite-like compounds, are natural and/or synthetic clays consisting of highly ordered two-dimensional hydroxide sheets, where M2+, M3+, and An− are divalent and trivalent cations, and the interlayer anions of valence n. Recently, LDHs have attracted great attention in the field of photocatalysis because of their characteristic layer structures, remarkable adsorption properties, and large specific surface areas. Recent applications of LDHs to the photocatalytic reactions such as the degradation of organic compounds, the water splitting (H2 and O2 evolution in the presence of sacrificial reagents), and the conversion of CO2 are reviewed in this chapter. Moreover, advances in synthesis techniques and characterization methods are also summarized. The variety of metal components in LDHs (M2+ and M3+) caused significant changes to the photocatalytic activities; in particular, the use of Ni−Al LDH enabled us to achieve the selective formation of CO in the photocatalytic conversion of CO2 in an aqueous solution, whereas the reduction of proton (H+) to H2 was suppressed.

Excessive usage of nonrenewable resources to meet global energy requirements has become a serious concern from the energy and environmental perspective. The continuous emission of CO2 in the environment from fossil fuels has become a major cause of global warming. Green hydrogen generation through seawater electrolysis has been an emergent technology that can play a prominent role in replacing conventional energy sources. Electrolysis of seawater using renewable sources such as solar, wind, and geothermal generates green hydrogen which has almost negligible harmful byproducts. Different ions present in seawater such as chlorides and sulfates impose serious corrosion problems during the electrolysis process as chloride ions penetrate the metal electrode surface and oxidize it and also liberate chlorine gas at the anode. For the electrolysis processes, catalysis plays a challenging task to reduce the kinetic barrier for the conversion of water molecules to hydrogen and oxygen products. Photoelectrocatalysts are another kind of semiconductor-based catalyst in which band gap, exchange charge carrier, and surface area play key roles in the water-splitting process. Two-dimensional nanomaterials offer many advantages like high specific surface area for electron transfer, high tunable functionalities, and flexible structural properties that make them suitable for different applications. Layered double hydroxide (LDH) as a highly efficient catalyst has the potential to perform the hydrogen production process as per the industrial application. LDH has many advantages in an effective water-splitting mechanism that includes easy synthesis methods, flexible morphology, long-term stability, and adaptability to different applications. Another major advantage is the corrosion inhibition property of LDH by different mechanisms like adsorption of corrosion-responsible ions, self-healing technique, and protective film formation which are discussed briefly in this review. This review provides a state-of-the-art analysis about the various important strategies to be adopted for effective seawater electrolysis. Finally, we examine the new challenges and the novel approaches to suppress corrosion processes during seawater electrolysis.

The peculiar properties of layered Double Hydroxides (LDH) have progressively drawn the attention of the scientific community. The main characteristic of LDH is the ability to capture anionic species (organic and inorganic) to build different composites. This is made possible by the sandwich structure of the LDH, similar to the brucite architecture, made up of positive charged lamellas interspersed by anions. Several distant fields, ranging from medicine to physics and engineering, exhibit interest in LDH applications. To satisfy all those requirements, energy was spent to sculpt LDHs physical and chemical properties and for designing layered double hydroxides “ad hoc” for different needs and employments. Notably, among the many applications, those related to metallurgical processes and products are of particular interest. This paper presents the characteristics, the main preparation routes and reviews the applications of LDH to metallurgy with some examples taken from the experimental research of the author.

Will blue hydrogen lock us into fossil fuels forever?

Hydrogen will be important in decarbonized energy systems. The primary ways to produce low emission hydrogen are from renewable electricity using electrolyzers, called green hydrogen, and by reforming natural gas and capturing and storing the CO2, known as blue hydrogen. In this study, the degrees to which blue and green hydrogen are complementary or competitive are analyzed through a sensitivity analysis on the electrolyzer costs, and natural gas price. This analysis is performed on four bases: what is the cost-effective relative share between blue and green hydrogen deployment, how their deployment influences the price of hydrogen, how the price of CO2 changes with the deployment of these two technologies, and whether infrastructure can economically be shared between these two technologies. The results show that the choice of green and blue hydrogen has a tremendous impact, where an early deployment of green leads to higher hydrogen costs and CO2 prices in 2030. Allowing for blue hydrogen thus has notable benefits in 2030, giving cheaper hydrogen with smaller wider socioeconomic impacts. In the long term, these competitive aspects disappear, and green and blue hydrogen can coexist in the European market without negatively influencing one another.

Chapter nine - Layered double hydroxide as electrode material for high-performance supercapattery

Layered double hydroxides (LDHs) are a class of ionic lamellar compounds made up of positively charged brucite-like layers with an interlayer region containing charge compensating anions and solvation molecules. Delamination of LDHs is an interesting route for producing positively charged thin platelets with a thickness of a few atomic layers, which can be used as nanocomposites for polymers or as building units for making new designed organic-inorganic or inorganic-inorganic nanomaterials. The synthesis of nanosized LDH platelets can be generally classified into two approaches, bottom-up and top-down. It requires modification of the LDH interlamellar environment and then selection of an appropriate solvent system. In DDS intercalated LDHs, the aliphatic tails of the DDS- anions exhibit a high degree of interdigitation in order to maximize guest-guest dispersive interactions. Bellezza reported that the LDH colloids can also been obtained by employing a reverse microemulsion approach.

Emerging contaminants (ECs) are a group of anthropogenic organic pollutants known to have a host of adverse environmental and health implications. The removal of such pollutants from aqueous environments to ensure water is of a quality fit for reuse is therefore highly important and gaining considerable interest. Whilst there are multiple approaches used for EC remediation from water matrices, sorption using layered double hydroxides (LDHs) has been reported as a suitable technique. LDHs are interesting clay-like materials with numerous properties which lend LDHs to being suitable sorbent materials. Such properties include low toxicity, anion exchange capacity and tuneable structures through possible variations in metals, anions and preparation techniques. To design a successful sorbent material, it is important to fully understand the materials structure-property-function relationship. However, in the application of LDHs as sorbent materials for the removal of organic pollutants, this relationship is not well understood. Hence the ability to design bespoke high-performing LDH sorbent material is currently limited.This review considers the impact of structure and related physiochemical properties of LDHs on their sorption capacity for the removal of organic pollutants from water matrices. Methyl Orange (MO) is first considered as a model pollutant, with the importance of the characteristics of the metal layers, interlayer anions and resulting textual properties of LDHs on reported sorption capacity observed. A comparison is then made between the findings from the MO case study and for the sorption of other organic pollutants using LDHs, with a particular focus on pharmaceuticals. Finally, the role of environmental conditions and considerations linked to possible commercial applications are discussed, with recommendations made for future work.

Layered double hydroxides (LDHs) are versatile stable materials, whose structures are two-dimensional cationic layers stacking together with various anions via electrostatic interactions. LDHs have been widely used in synthesis, pharmaceuticals, and catalysis. Recently, LDHs, LDH-based photocatalysts, and LDH derivatives (such as mixed metal oxides, MMO) have attracted extensive research attention because of their potential usefulness in tackling environmental problems and the energy crisis. In this chapter, we summarize the main synthesis methods for LDHs-based photocatalysts, and their applications in photocatalytic areas, especially in photocatalytic degradation of water contamination. The photocatalytic mechanisms, applications of LDHs in other aspects of photocatalysis, and comparisons with other photocatalysts are also briefly mentioned. At the end of the chapter, a perspective on the LDH-based composite materials is presented.

Many different technical techniques can be used to manufacture hydrogen from both renewable and nonrenewable feed supplies while reducing greenhouse gas emissions. Hydrogen is employed in upcoming low-carbon energy systems since it emits relatively little carbon. The bulk of the present green hydrogen activities are geared toward the possibility of a green hydrogen market. Green hydrogen and origin guarantees have been defined using various approaches. These vary according on the following: the carbon financial statements' characteristics; the emission threshold at which hydrogen is classified as green; the plan's feedstock and production techniques; and whether or not sustainable hydrogen must be produced through the use of renewable energy. To overcome obstacles and improve green hydrogen production's viability as a sustainable energy source, research is always moving forward. To hasten green hydrogen's integration into clean energy transitions and slow down global warming, research efforts are concentrated on increasing its efficiency, cutting prices, and broadening its applications. A study that focused on the near-zero carbon production method of green hydrogen by electrolysis using renewable energy sources underscored the advancements and prospects of this field of study. This article describes the current techniques for creating hydrogen from sustainable and renewable energy sources. Keywords: Green Hydrogen, Biomass, Efficiency, Renewable, Hydrogen production.

Transition metal layered double hydroxides (LDHs) are effective electrode materials that can address the sluggish kinetics of the oxygen evolution reaction (OER) at the anode during electrocatalytic hydrogen generation from water, but the application of LDHs is expected to make a breakthrough toward high conductivity and stability. In this study, Ni3S2 and Ta-doped NiFe LDH composite cross-linked nanosheets were grown on nickel foam (Ni3S2@Ta-NiFe LDH/NF). The optimized material exhibited a significantly increased specific surface area, along with excellent OER performance and stability. At 50 and 100 mA cm-2 in 1 M KOH, the overpotentials are 188.5 and 203.4 mV, respectively, markedly below RuO2/NF's 300.6 and 339 mV. The material demonstrates excellent durability, maintaining stable performance for 50 h. The high conductivity and stability are further confirmed in the Pt/C and Ni3S2@Ta-NiFe LDH-based two-electrode system with excellent activity (1.472 V at 10 mA cm-2) and sustained durability. Density functional theory (DFT) calculations reveal that the heterostructure of Ni3S2 and Ta-NiFe LDH facilitates interfacial charge transfer, thus improving conductivity. Simultaneously, the electron-deficient state of the metal site weakens the strong adsorption of OER intermediates and accelerates OER kinetics. This work offers fresh perspectives on LDH electrocatalyst design and advances sustainable, cost-effective hydrogen production technology, marked by enhanced efficiency and stability.