Hussein A. Younus, Rashid Al Hajri, Nazir Ahmad
et al.
Abstract Green hydrogen is emerging as a pivotal energy carrier in the global transition toward decarbonization, offering a sustainable alternative to fossil fuels in sectors such as heavy industry, transportation, power generation, and long-duration energy storage. Despite its potential, large-scale deployment remains hindered by significant economic, technological, and infrastructure challenges. Current production costs for green hydrogen range from USD 3.8 to 11.9/kg H2, significantly higher than gray hydrogen at USD 1.5–6.4/kg H2, due to high electricity prices and electrolyzer capital costs exceeding USD 2000 per kW. This review critically examines the key bottlenecks in green hydrogen production, focusing on water electrolysis technologies, electrocatalyst limitations, and integration with renewable energy sources. The economic viability of green hydrogen is constrained by high electricity consumption, capital-intensive electrolyzer costs, and operational inefficiencies, making it uncompetitive with fossil fuel-based hydrogen. Infrastructure and supply chain challenges, including limited hydrogen storage, transport complexities, and critical material dependencies, further restrict market scalability. Additionally, policy and regulatory gaps, disparities in financial incentives, and the absence of a standardized certification framework hinder international trade and investment in green hydrogen projects. This review also highlights market trends and global initiatives, assessing the role of government incentives and cross-border collaborations in accelerating hydrogen adoption. While technological advancements and cost reductions are progressing, overcoming these challenges requires sustained innovation, stronger policy interventions, and coordinated efforts to develop a resilient, scalable, and cost-competitive green hydrogen sector.
Chemical technology, Physical and theoretical chemistry
Qiqi Yang, Antonio Virgilio Failla, Petri Turunen
et al.
Abstract Stimulated emission depletion (STED) microscopy, a key optical super-resolution imaging method, has extended our ability to view details to resolution levels of tens of nanometers. Its resolution depends on fluorophore de-excitation efficiency, and increases with depletion laser power. However, high-power irradiation permanently turns off the fluorescence due to photo-bleaching of the fluorophores. As a result, there is a trade-off between spatial resolution and imaging time. Here, we overcome this limitation by introducing reactivatable STED (ReSTED) based on the photophysical properties of the nanographene dibenzo[hi,st]ovalene (DBOV). In contrast to the photo-induced decomposition of other fluorophores, the fluorescence of DBOV is only temporarily deactivated and can be reactivated by near-infrared light (including the 775 nm depletion beam). As a result, this fluorophore allows for hours-long, high-resolution 3D STED imaging, greatly expanding the applications of STED microscopy.
Abstract Lead‐based organic‐inorganic hybrid perovskites show promise as photovoltaic materials due to their high energy conversion efficiencies. However, concerns regarding lead toxicity and the poor environmental and operational stability of the organic cationic group have limited their widespread application. To address these challenges, the design of all‐inorganic lead‐free halide perovskites offers potential solutions for photovoltaic applications. Here, two layered perovskite derivatives, Rb3Mo2Cl9 and Rb3Mo2Br9, are explored, and their electronic, structural, and photovoltaic properties are analyzed using advanced theoretical calculations. Rb3Mo2Br9 exhibits a suitable direct bandgap of 1.60 eV, making it a promising candidate for use as a light absorber in low‐cost, high‐efficiency solar cells. On the other hand, Rb3Mo2Cl9 demonstrates a wide direct bandgap exceeding 1.70 eV, positioning it as a viable option for use as a top cell in tandem photovoltaic systems alongside silicon. Both materials display ideal optical properties in the visible light region and hold promise as excellent inorganic lead‐free perovskite alternatives.
Vladislava A. Pigareva, Valeria I. Marina, Andrey V. Sybachin
Biocidal compositions based on interpolyelectrolyte complexes and a low molecular weight antibiotic can become a promising material for creating biocidal coatings, as they combine wash-off resistance and dual biocidal action due to the biocide and the polycation. Molecular mass characteristics of polymers play an essential role in the physics and mechanical properties of the coatings. In this work, the properties of polydiallyldimethylammonium chloride (PDADMAC) coatings of various molecular weights are investigated and assumptions are made about the optimal molecular weight needed to create antibacterial compositions. To study the resistance to washing off and moisture saturation of the coatings, the gravimetric method was used, and the adhesive properties of the coatings were studied by dynamometry. It has been established that an increase in molecular weight affects the wash-off resistance of coatings, but does not affect moisture absorption and adhesion mechanics of coatings. All samples of PDADMAC were demonstrated to exhibit the same antibacterial activity. Thus, when developing systems for creating antibacterial coatings, it must be taken into account that in order to create stable coatings, the requirement to use PDADMAC with a high degree of polymerization is necessary for the coating desorption control during wash off-but not mandatory for the control of mechanical and antibacterial properties of the coating.
Using first principles calculations, the possibility of controlling the electronic band structure of the single-layer graphene was investigated. It is shown that when potassium atoms are adsorbed on the graphene surface, an energy gap appears in its electronic spectrum. It was also observed that the band gap strongly depends on the number of adsorbed atoms, namely, with an increase in the number of adsorbed atoms, the band gap in graphene can either increase or disappear. For example, when there is one potassium atom per 32 carbon atoms in the graphene lattice, the band gap is ΔE = 0,1 eV. An increase in the number of potassium atoms to two leads to disappearance of the energy gap, while for three potassium atoms ΔE = 0,22 eV. It should also be noted that the appearance of a band gap during adsorption does not break the symmetry of the graphene sublattices. This observation seems interesting to us, since according to many authors, it is the break of the sublattices symmetry that is the main reason for the appearance of a band gap in graphene.
AbstractThe rate coefficients of ethynyl radical reaction with n‐butane were computed for the first time using the canonical variational transition state theory (CVT) between 150 and 5000 K. The structures and frequencies of all the stationary points are computed at the M06‐2X/6‐31+G(d,p) level of theory. The potential energy surface scanned shows that two rotamers exist for n‐butane. Three different transition states were identified for each rotamers. The rate coefficients obtained over the temperature range of 150–500 K using the M06‐2X/6‐31+G(d,p) theory were used to derive the Arrhenius expression: k(T) = 1.35 × 10−17 T2.0 exp[1326/T] cm3 molecule−1 s−1. It is shown that the H‐abstraction from –CH2– group of n‐butane is the dominant reaction channel over the complete temperature range.
In this paper, we used the successive ionic layer adsorption and reaction (SILAR) method, and the BiVO4 nanoparticles were successfully deposited on the surface of TiO2 nanotube arrays (NTs). The coupling of BiVO4 and TiO2 NTs significantly improved the photocatalytic activity of Rhodamine B (RhB) degradation by visible light. The prepared heterostructured BiVO4/TiO2 NTs photocatalysts were characterized by field emission scanning microscope (FE-SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, transient photocurrent responses. The prepared BiVO4/TiO2 NTs-7 showed the significantly improved photocatalytic activity for the degradation of RhB. This excellent photocatalytic performance is attributed to the enhancement of visible light absorption and separation efficiency of photogenerated charge carriers on heterostructured BiVO4/TiO2 NTs. This simple method could be able to utilize in the preparation of high-performance heterostructures for environmental photocatalytic, sensing, and photo-voltaic applications.
Industrial electrochemistry, Physical and theoretical chemistry
The methods of preparation, as well as the structure and most relevant physical
properties of amorphous materials based on ferroelectrics with perovskite structure are
reviewed. The theoretical basis for the possibility of ferroelectricity in non-crystalline solids is
discussed. The structural relaxation in a glassy state and the crystallization processes
leading to the formation of a ferroelectric phase are considered. The structure and physical
properties of thin-film amorphous ferroelectrics that demonstrate noticeable differences from
the properties of the same materials in bulk state are discussed separately
Crystallography, Physical and theoretical chemistry
Spiral waves represent an important example of dissipative structures observed in many distributed systems in chemistry, biology and physics. By definition, excitable media occupy a stationary resting state in the absence of external perturbations. However, a perturbation exceeding a threshold results in the initiation of an excitation wave propagating through the medium. These waves, in contrast to acoustic and optical ones, disappear at the medium's boundary or after a mutual collision, and the medium returns to the resting state. Nevertheless, an initiation of a rotating spiral wave results in a self-sustained activity. Such activity unexpectedly appearing in cardiac or neuronal tissues usually destroys their dynamics which results in life-threatening diseases. In this context, an understanding of possible scenarios of spiral wave initiation is of great theoretical importance with many practical applications. This article is part of the theme issue ‘Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)’.
Practical utilization of energy densities near the theoretical limit for R3m layered oxide positive electrode materials is dependent on the stability of the electrochemical performance of these materials at or near full delithiation. To develop new chemistries and novel approaches toward the improvement of the electrochemical performance of these materials at such high states of charge, a robust understanding of the failure mechanisms limiting current materials is necessary. Thorough analysis of LixCo1–yAlyO2 and LixNi1–yAlyO2 as well as LixNi0.8Co0.2O2 and LixNi0.8Co0.15Al0.05O2 (1 ≥ x ≥ 0 and 0.2 ≥ y ≥ 0) enabled the identification of key relationships between the transition metal chemistry of the electrode, its structural stability, and cycling characteristics at or near complete delithiation (4.75 V). Extensive characterization of these materials was achieved by a multitude of physical and electrochemical techniques to investigate the relative importance of surface vs bulk phenomena. The resulting in...