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doi: 10.1039/d3cp04611gpmid: 39253852
The many-body problem is a common issue, irrespective of the scale of entities under consideration. From electrons to atoms, small molecules like simple inorganic or organic structures, large molecules like proteins or polymers, nanometer- or micrometer-sized particles, granular matter, and even galaxies, the precise determination or estimation of geometrical locations and momentum energy of individual entities, and interaction forces between these millions of entities, is impossible but unfortunately important for understanding the collective physical properties like mechanical and electrical characteristics of the whole system. Despite foreseeable difficulties and complexities, attempts to estimate “interparticle” forces have never stopped using traditional Newtonian models, quantum mechanical approaches, and density functional theory. In this review, a simple approach integrating the free volume and Eyring's rate process theory is summarized and its application across a wide range of scales from electrons to the universe is presented in a unified manner. The focus is on comparisons between theoretical predictions and experimental results.
Wang, Yule; Cui, Bin-bin; Zhao, Yiming; Lin, Tao; Li, Juan
doi: 10.1039/d4cp02010cpmid: 39387127
The issue of energy scarcity has become more prominent due to the recent scientific and technological advancements. Consequently, there is an urgent need for research on sustainable and renewable resources. Solar energy, in particular, has emerged as a highly promising option because of its pollution-free and environment-friendly characteristics. Among the various solar energy technologies, perovskite solar cells have attracted much attention due to their lower cost and higher photoelectric conversion efficiency (PCE). However, the inherent instability of perovskite materials hinders the commercialization of such devices. The utilization of scanning tunneling microscopy/spectroscopy (STM/STS) can provide valuable insights into the fundamental properties of different perovskite materials at the atomic scale, which is crucial for addressing this challenge. In this review, we present the recent research progress of STM/STS analysis applied to various perovskites for solar cells, including halide perovskites, two-dimensional Ruddlesden–Popper perovskites, and oxide perovskites. This comprehensive overview aims to inspire new ideas and strategies for optimizing solar cells.
Liu, Runze; Liu, Jianyong; Zhou, Panwang
doi: 10.1039/d4cp02499kpmid: 39380550
The quest for thermally stable energetic materials is pivotal in advancing the safety of applications ranging from munitions to aerospace. This perspective delves into the role of theoretical methodologies in interpreting and advancing the thermal stability of energetic materials. Quantum chemical calculations offer an in-depth understanding of the molecular and electronic structure properties of energetic compounds related to thermal stability. It is also essential to incorporate the surrounding interactions and their impact on molecular stability. Ab initio molecular dynamics (AIMD) simulations provide detailed theoretical insights into the reaction pathways and the key intermediates during thermal decomposition in the condensed phase. Analyzing the kinetic barrier of rate-determining steps under various temperature and pressure conditions allows for a comprehensive assessment of thermal stability. Recent advances in machine learning have demonstrated their utility in constructing potential energy surfaces and predicting thermal stability for newly designed energetic materials. The machine learning-assisted high-throughput virtual screening (HTVS) methodology can accelerate the discovery of novel energetic materials with improved properties. As a result, the newly identified and synthesized energetic molecule ICM-104 revealed excellence in performance and thermostability. Theoretical approaches are pivotal in elucidating the mechanisms underlying thermal stability, enabling the prediction and design of enhanced thermal stability for emerging EMs. These insights are instrumental in accelerating the development of novel energetic materials that optimally balance performance and thermal stability.
Sasikala Devi, Assa Aravindh; Javaheri, Vahid; Pallaspuro, Sakari; Komi, Jukka
doi: 10.1039/d4cp02233epmid: 39400263
Hydrogen (H) is considered as the key element in aiding the initiated green energy transition. To facilitate this, efficient and durable technologies need to be developed for the generation, storage, transportation, and use of H. All these value chain stages require materials that can withstand continuous exposure to H. Once absorbed, H can eventually concentrate to critical levels in a stressed microstructure, inducing specific damage mechanisms and consecutive loss of mechanical properties. This is known as hydrogen embrittlement (HE). Being one of the most significant structural material types, steels are widely used throughout the H value chain. They can suffer from HE, and numerous attempts are made towards understanding and mitigating this complex phenomenon. While originating at a size scale of atoms, HE acts on multiple spatio-temporal scales, and combined efforts of experimental and modelling techniques are needed to deal with it. This perspective is devoted to assimilating the knowledge that can be generated by density functional theory (DFT) methods to understand interactions between H and iron-based materials, and to promote finding solutions to HE in metallic materials in general. We aim to provide a comprehensive understanding of the properties calculated using DFT that can help advance finding novel H-resistant high-strength materials that facilitate the green shift at sufficient performance levels to meet the growing future needs.
Badía-Domínguez, Irene; Wang, Deliang; Nash, Rosie; Jolín, Víctor Hernández; Collison, David; Shanmugam, Muralidharan; Li, Hongxiang; Hartl, František; Ruiz Delgado, M. Carmen
doi: 10.1039/d4cp02729apmid: 39279718
During the last decade, there has been an increasing interest in the rationalisation of how structural changes stabilise (or destabilise) diradical systems. Demonstrated herein is that indolocarbazole (ICz) diradicals, substituted with dicyanomethylene (DCM) groups, are useful motifs for dynamic covalent chemistry by self-assembling from isolated monomers to cyclophane structures. The comparison of ICz-based systems substituted with DCM groups in para- or meta-positions (p-ICz-CN and m-ICz-CN) and their short-chain carbazole analogues (p-Cz-CN and m-Cz-CN) may identify new potential design strategies for stimuli-responsive materials. The principal objectives of this investigation are the elucidation of (i) the connection between diradical character and the cyclophane stability, (ii) the spatial disposition of the cyclophane structures, (iii) the monomer/cyclophane interconversion both in solution and solid state in response to external stimuli and (iv) the impact that the different π-conjugation and electronic communication between the DCM terminals exerts on the electronic adsorption of the diradicals and their redox behavior. The spontaneous nature of the cyclophane structure is supported by the negative relative Gibbs free energies calculated at 298 K and experimentally by UV-Vis and Raman spectroscopy of the initial yellow solid powder. The conversion to monomeric species having diradical character was demonstrated by variable-temperature (VT) EPR, UV-Vis, Raman and IR measurements, resulting in appreciable chromic changes. In addition, electrochemical oxidation and reduction convert the cyclophane dimer (m-ICz-CN)2 to the monomer monocations and dianions, respectively. This research demonstrates how the chemical reactivity and physical properties of π-conjugated diradicals can be effectively tuned by subtle changes in their chemical structures.
Xu, Piao; Wang, Dongdong; Li, Duoduo; Long, Jinyou; Zhang, Song; Zhang, Bing
doi: 10.1039/d4cp02594fpmid: 39229763
Despite the important role of the dark 1nπ* state in the photostability of thymidine in aqueous solution, no detailed ultraviolet (UV) wavelength-dependent investigation of the 1nπ* quantum yield (QY) in aqueous thymidine has been experimentally performed. Here, we investigate the wavelength-dependent photoemission spectra of aqueous thymidine from 266.7 to 240 nm using liquid-microjet photoelectron spectroscopy. Two observed ionization channels are assigned to resonant ionizations from 1ππ* to the cationic ground state D0 (π−1) and 1nπ* to the cationic excited state D1 (n−1). The weak 1nπ* → D1 ionization channel appears due to ultrafast 1ππ* → 1nπ* internal conversion within the pulse duration of ∼180 fs. The obtained 1nπ* quantum yields exhibit a strong wavelength dependence, ranging from 0 to 0.27 ± 0.01, suggesting a hitherto uncharacterized 1nπ* feature. The corresponding vertical ionization energies (VIEs) of D0 and D1 of aqueous thymidine are experimentally determined to be 8.47 ± 0.12 eV and 9.22 ± 0.29 eV, respectively. Our UV wavelength-dependent QYs might indicate that different structural critical points to connect the multidimensional 1ππ*/1nπ* conical intersection seam onto the multidimensional potential energy surface of the 1ππ* state might exist and determine the relaxation processes of aqueous thymidine upon UV excitation.
Silva-Dias, Leonardo; Epstein, Irving R.; Dolnik, Milos
doi: 10.1039/d4cp01777cpmid: 39046428
We investigate the emergence of Turing patterns in a system growing as a rotating spiral in two dimensions, utilizing the photosensitivity of the chlorine dioxide–iodine–malonic acid (CDIMA) reaction to control the growth process. We observe the formation of single and multiple (double and triple) stationary spiral patterns as well as transitional patterns. From numerical simulations of the Lengyel–Epstein model with an additional term to account for the effects of illumination on the reaction, we analyze the relationship between the final morphologies and the radial and angular growth velocities, identify conditions conducive to the formation of transitional structures, examine the importance of the size of the initial nucleation site in determining the spiral's multiplicity, and evaluate the stability and robustness of these Turing patterns. Our results indicate how inclusion of rotational degrees of freedom in the growth process may lead to the formation of a diverse new class of patterns in chemical and biological systems.
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