Physical Chemistry Chemical Physics

doi: 10.1039/d4cp90060jpmid: N/A

doi: 10.1039/d4cp90061hpmid: N/A

Katayama, Kenji

doi: 10.1039/d3cp06211bpmid: 38497609

Pattern-illumination time-resolved phase microscopy (PI-PM) is a technique used to study the microscopic charge carrier dynamics in photocatalytic and photovoltaic materials. The method involves illuminating a sample with a pump light pattern, which generates charge carriers and they decay subsequently due to trapping, recombination, and transfer processes. The distribution of photo-excited charge carriers is observed through refractive index changes using phase-contrast imaging. In the PI-PM method, the sensitivity of the refractive index change is enhanced by adjusting the focus position, the method takes advantage of photo-excited charge carriers to observe non-radiative processes, such as charge diffusion, trapping in defect/surface states, and interfacial charge transfer of photocatalytic and photovoltaic reactions. The quality of the image sequence is recovered using various informatics calculations. Categorizing and mapping different types of charge carriers based on their response profiles using clustering analysis provides spatial information on charge carrier types and the identification of local sites for efficient and inefficient photo-induced reactions, providing valuable information for the design and optimization of photocatalytic materials such as the cocatalyst effect.

Singh, Avtar; Dhau, Jaspreet; Kumar, Rajeev; Badru, Rahul; Kaushik, Ajeet

doi: 10.1039/d3cp05740bpmid: 38497121

This review article explores the fascinating realm of fluorescence using organochalcogen molecules, with a particular emphasis on tellurium (Te). The discussion encompasses the underlying mechanisms, structural motifs influencing fluorescence, and the applications of these intriguing phenomena. This review not only elucidates the current state of knowledge but also identifies avenues for future research, thereby serving as a valuable resource for researchers and enthusiasts in the field of fluorescence chemistry with a focus on Te-based molecules. By highlighting challenges and prospects, this review sparks a conversation on the transformative potential of Te-containing compounds across different fields, ranging from environmental solutions to healthcare and materials science applications. This review aims to provide a comprehensive understanding of the distinct fluorescence behaviors exhibited by Te-containing compounds, contributing valuable insights to the evolving landscape of chalcogen-based fluorescence research.

Herzfeld, Judith

doi: 10.1039/d4cp00005fpmid: 38502180

With the increasing sophistication of each, theory and experiment have become highly specialized endeavors conducted by separate research groups. A result has been a weakening of the coupling between them and occasional hostility. Examples are given and suggestions are offered for strengthening the traditional synergy between theory and experiment.

Pal, Ranita; Chattaraj, Pratim Kumar

doi: 10.1039/d3cp06321fpmid: 38497096

Noble gases (Ngs) are recognized as the least reactive elements due to their fully filled valence electronic configuration. Their reluctance to engage in chemical bond formation necessitates extreme conditions such as low temperatures, high pressures, and reagents with high reactivity. In this Perspective, we discuss our endeavours in the theoretical prediction of viable Ng complexes, emphasizing the pursuit of synthesizing them under nearly ambient conditions. Our research encompasses various bonding categories of Ng complexes and our primary aim is to comprehend the bonding mechanisms within these complexes, utilizing state-of-the-art theoretical tools such as natural bond orbital, energy decomposition, and electron density analyses. These complex types manifest distinct bonding scenarios. In the non-insertion type, the donor–acceptor interaction strength hinges on the polarizing ability of the binding atom, drawing the electron density of the Ng towards itself. In certain instances, especially with heavier Ng elements, this interaction reaches a magnitude where it can be considered a covalent bond. Conversely, in most insertion cases, the Ng prefers to share electrons to form a covalent bond on one side while interacting electrostatically on the other side. In rare cases, both bonds may be portrayed as electron-shared covalent bonds. Furthermore, a host cage serves as an excellent platform to explore the limits of achieving Ng–Ng bonds (even for helium), under high pressure.

Hlushko, Hanna; Ramos-Ballesteros, Alejandro; Chen, Ping; Zhang, Xin; Rosso, Kevin M.; Pearce, Carolyn I.; LaVerne, Jay A.

doi: 10.1039/d3cp06305dpmid: 38477345

The generation and stabilization of gamma radiation-induced hydrogen atoms in gibbsite (Al(OH)3) nanoplates is directly related to the nature of residual ions from synthetic precursors used, whether nitrates or chlorides. The concentration of hydrogen atoms trapped in the interstitial layers of gibbsite is lower and decays faster in comparison to boehmite (AlOOH), which could affect the management of these materials in radioactive waste.

You, Xiao; Maharjan, Sangita; Vinodgopal, Kizhanipuram; Atkin, Joanna M.

doi: 10.1039/d3cp04711cpmid: 38168951

Graphene oxide (GO) has attracted substantial interest for its tunable properties and as a possible intermediate for the bulk manufacture of graphene. GO and its reduced derivatives display electronic and optical properties that depend strongly on their chemical structure, and with proper functionalization, GO can have a desirable bandgap for semiconductor applications. However, its chemical activity leads to a series of unclear chemical changes under ambient conditions, resulting in changes in color and solubility upon exposure to light. In this paper, we study the properties of fresh and spontaneously reduced GO under ambient conditions using tip-enhanced Raman spectroscopy (TERS) to map its nanometer scale chemical and structural heterogeneity. We observe different types of defect sites on reduced GO (rGO) by spatially mapping the D to G band peak ratio and D and G band spectral positions. The higher spatial resolution and out-of-plane polarization compared to conventional micro-Raman spectroscopy enables us to resolve unusual features, including D-band shifting on rGO. Based on statistical analysis of the spatial variations in modes and theoretical calculations for different functional groups, we conclude the reduction mechanism of GO is a self-photocatalytic reduction with the participation of water and visible light, in which the rate determining step is electron transport through the metal substrate and ion diffusion on the GO surface. These results demonstrate that TERS can reveal structural and chemical details elucidating reduction mechanisms, through the examination of samples at different time points.

Zhang, Zhongliang; Kato, Ken; Tamaki, Hajime; Matsuki, Yoh

doi: 10.1039/d3cp06280epmid: 38317640

A novel method for background signal suppression is introduced to improve the selectivity of dynamic nuclear polarization (DNP) NMR spectroscopy in the study of target molecules within complex mixtures. The method uses subtraction between positively and negatively enhanced DNP spectra, leading to an improved contrast factor, which is the ratio between the target and background signal intensities. The proposed approach was experimentally validated using a reverse-micelle system that confines the target molecules together with the polarizing agent, OX063 trityl. A substantial increase in the contrast factor was observed, and the contrast factor was optimized through careful selection of the DNP build-up time. A simulation study based on the experimental results provides insights into a strategy for choosing the appropriate DNP build-up time and the corresponding selectivity of the method. Further analysis revealed a broad applicability of the technique, encompassing studies from large biomolecules to surface-modified polymers, depending on the nuclear spin diffusion rate with a range of gyromagnetic ratios.

Gubitosa, Jennifer; Rizzi, Vito; Fini, Paola; Nuzzo, Sergio; Cosma, Pinalysa

doi: 10.1039/d4cp00174epmid: 38465407

According to circular bioeconomy principles, the use of kiwi peels to remove Direct Blue 78 (DB) from water is investigated during this work, proposing food waste as a recyclable adsorbent substrate. Direct Blue 78 (DB) was adopted as a model pollutant, employing its visible spectrum to monitor its adsorption. The adsorption process was thus fully characterized, investigating the roles of ionic strength, pH values, adsorbent/pollutant amounts, and temperature. The thermodynamics, kinetics, and adsorption isotherms were also studied. To extend the kiwi peels’ lifetime, quite complete desorption was obtained by adopting hot water as a safe and eco-friendly strategy. Despite the relatively low kiwi peels’ maximum adsorption capacity (6 mg g−1) for DB when adsorbed in the presence of NaCl, 10 cycles of adsorption/desorption were attempted, proposing the recycling of both the dye and kiwi peels as dictated by circular economy principles. Dyeing experiments were also performed, evidencing the dye's ability to color cotton fabrics after its recycling. Finally, the removal of other textile dyes, Direct Red 83 : 1 and Direct Yellow 86, was demonstrated in a mixture with DB. A preliminary investigation was performed to find the best working conditions for inducing the solid-state dye photodegradation, proposing a possible alternative for the adsorbent regeneration.