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We investigate the structures of hydrated electrons (e−aq) in one of water's solid phases, namely, clathrate hydrates (CHs). Using density functional theory (DFT) calculations, DFT-based ab initio molecular dynamics (AIMD), and path-integral AIMD simulations with periodic boundary conditions, we find that the structure of the e−aq@node model is in good agreement with the experiment, suggesting that an e−aq could form a node in CHs. The node is a H2O defect in CHs that is supposed to be composed of four unsaturated hydrogen bonds. Since CHs are porous crystals that possess cavities that can accommodate small guest molecules, we expect that these guest molecules can be used to tailor the electronic structure of the e−aq@node, and it leads to experimentally observed optical absorption spectra of CHs. Our findings have a general interest and extend the knowledge of e−aq into porous aqueous systems. [ABSTRACT FROM AUTHOR]

Developing efficient and anti‐corrosive oxygen reduction reaction (ORR) catalysts is of great importance for the applications of proton exchange membrane fuel cells (PEMFCs). Herein, we report a novel approach to prepare metal oxides supported intermetallic Pt alloy nanoparticles (NPs) via the reactive metal‐support interaction (RMSI) as ORR catalysts, using Ni‐doped cubic ZrO2 (Ni/ZrO2) supported L10−PtNi NPs as a proof of concept. Benefiting from the Ni migration during RMSI, the oxygen vacancy concentrations in the support are increased, leading to an electron enrichment of Pt. The optimal L10−PtNi−Ni/ZrO2−RMSI catalyst achieves remarkably low mass activity (MA) loss (17.8 %) after 400,000 accelerated durability test cycles in a half‐cell and exceptional PEMFC performance (MA=0.76 A mgPt−1 at 0.9 V, peak power density=1.52/0.92 W cm−2 in H2−O2/−air, and 18.4 % MA decay after 30,000 cycles), representing the best reported Pt‐based ORR catalysts without carbon supports. Density functional theory (DFT) calculations reveal that L10−PtNi−Ni/ZrO2−RMSI requires a lower energetic barrier for ORR than L10−PtNi−Ni/ZrO2 (direct loading), which is ascribed to a decreased Bader charge transfer between Pt and *OH, and the improved stability of L10−PtNi−Ni/ZrO2−RMSI compared to L10−PtNi−C can be contributed to the increased adhesion energy and Ni vacancy formation energy within the PtNi alloy. [ABSTRACT FROM AUTHOR]

Iron-based particles loaded on porous carbon materials have attracted extensive attention as catalysts for denitration and desulfurization reactions. However, the carbon support of a high-temperature denitration catalyst is inevitably oxidized in the presence of H2O and O2. The mechanism of denitration catalyst oxidation and its influence on the catalytic reaction remain to be further explored. Fe2O3-loaded graphene models with carbon vacancy (Gdef), hydroxyl (HyG), and carboxyl (CyG) were constructed to investigate the effects of hydroxylation and carboxylation on the catalytic activity of Fe2O3/graphene for oxidative desulfurization and denitration by using density functional theory (DFT) calculations. According to the analysis of structural properties and adsorption energy, the adsorption process of Fe2O3 on HyG and CyG was observed to have proceeded more favorably than that on Gdef. The density-of-states (DOS) results also affirmed that HyG and CyG promote the electron delocalization of Fe2O3 around the Fermi level, enhancing the chemical activity of Fe2O3. Moreover, adsorption energy analysis indicates that hydroxylation and carboxylation enhanced the adsorption of SO2 and H2O2 on Fe2O3/graphene while also maintaining preferable adsorption stability of NO. Furthermore, mechanistic research explains that adsorbed H2O2 on HyG and CyG directly oxidizes NO and SO2 into HNO2 and H2SO4 following a one-step reaction. The results provide a fundamental understanding of the oxidized catalyst on catalytic denitration and desulfurization reactions. [ABSTRACT FROM AUTHOR]

A palladium‐catalyzed chemoselective coupling of readily available bicyclo[1.1.1]pentanyl alcohols (BCP−OH) with various halides is reported, which offers expedient approaches to a wide range of cyclobutanone and β,γ‐enone skeletons via single or double C−C activation. The chemistry shows a broad substrate scope in terms of both the range of BCP−OH and halides including a series of natural product derivatives. Moreover, dependency of reaction chemodivergence on base additive has been investigated through experimental and density functional theory (DFT) studies, which is expected to significantly enrich the reaction modes and increase the synthetic potential of BCP−OH in preparing more complex molecules. [ABSTRACT FROM AUTHOR]

Carbamazepine (CBZ) is a widely used anticonvulsant drug that has been detected in aquatic environments. This study investigated the toxicity of its by-products (CBZ-BPs), which may surpass CBZ. Unlike the previous studies, this study offered a more systematic approach to identifying toxic BPs and inferring degradation pathways. Furthermore, quadrupole time-of-flight (QTOF) and density functional theory (DFT) calculations were employed to analyze CBZ-BP structures and degradation pathways. Evaluation of total organic carbon (TOC) and total nitrogen (TN) mineralization rates, revealed carbon (C) greater susceptibility to mineralization compared with nitrogen (N). Furthermore, three rules were established for CBZ decarbonization and N removal during degradation, observing the transformation of aromatic compounds into aliphatic hydrocarbons and stable N-containing organic matter over time. Five potentially highly toxic BPs were screened from 14 identified BPs, with toxicity predictions guiding the selection of commercial standards for quantification and true toxicity testing. Additionally, BP207 emerged as the most toxic, supported by the predictive toxicity accumulation model (PTAM). Notably, highly toxic BPs feature an acridine structure, indicating its significant contribution to toxicity. These findings offered valuable insights into the degradation mechanisms of emerging contaminants and the biosafety of aquatic environments during deep oxidation. [Display omitted] • The rules of CBZ decarbonization and nitrogen removal during UV/H 2 O 2 were deduced. • Key by-products were quantified on concentration and toxicity. • Acridine structure was the main toxic contributor. • Carbon was more likely to be mineralized than nitrogen during degradation. • The degradation pathways were obtained by combing N-transformation and DFT. [ABSTRACT FROM AUTHOR]

In recent decades, nitrogen-containing heterocyclic compounds (NHCs) have been widely synthesized and applied due to their excellent coordination capability of heterocyclic N atoms. However, their high toxicity and poor biodegradability pose significant hazards to aquatic ecosystems. Three characteristic NHCs (cNHCs) with similar molecular structures but minor differences in the number and position of N atoms, namely benzotriazole (BTA), benzimidazole (BMZ), and indazole (IDZ), were selected to evaluate impacts of these differences on their degradation behaviors during UV/H 2 O 2 treatments. It was found that the key mechanism for the removal of BTA, BMZ, and IDZ in the UV/H 2 O 2 processes was the generation of ∙OH through UV-excited H 2 O 2 decomposition. Density functional theory (DFT) calculations revealed that the variation in the number and position of heterocyclic ring N atoms significantly affected the electron cloud distribution of the cNHCs, thereby resulting in different reactivities. Mineralization results and N evolution experiments indicated that N elements were initially released in the form of ammonia nitrogen during UV/H 2 O 2 treatments, which then underwent oxidation to form nitrite and nitrate. The two ortho-N atoms were most easily mineralized and release inorganic nitrogen, followed by the two meta-N atoms. However, the BTA compound containing three N atoms, exhibited inertness towards radicals after hydroxylation, thereby hindering mineralization. A dual-directional transformation products (TPs) identification protocol was employed to identify 30 TPs of the cNHCs and propose recommended degradation pathways. Furthermore, Vibrio fischeri bioluminescence inhibition bioassay and QSAR prediction models were used to preliminarily screen and identify 13 toxic TPs with potential ecological risks. [Display omitted] • N-atom number and position influenced electron density, impacting reactivity. • BTA showed superior ROS affinity compared to BMZ and IDZ due to its N-N N moiety. • Reactive sites for ROS were located by FED theory and Fukui function. • Dual-directional TPs-identification protocol helped identify 6 novel pathways. • V. fischeri bioassay combined with QSAR model to screen out 13 toxic TPs. [ABSTRACT FROM AUTHOR]

Remdesivir (RDV), dexamethasone (DEX) and hydroxychloroquine (HCQ) were widely used in the treatment of COVID-19 pneumonia, possibly causing environmental risks and drug-resistance viruses. This study elucidated the degradation mechanisms and potential toxicity risks of the three anti-COVID-19 drugs by UV and ultraviolet-coupled advanced oxidation processes (UV/AOPs). All the drugs could be degraded by more than 98% within 3 min under the following optimal conditions: pH of 5.0 and drug-to-oxidant (H 2 O 2) molar ratio of 1:200. Combined with density functional theory (DFT) analysis and high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS), twenty-four transformation products (TPs) were detected and the main degradation pathways were investigated. Based on bacterial luminescence inhibition test and the peak-area evolution of TPs, RDV and HCQ showed an obvious toxicity-increase region when TPs were generated in large quantities, while the toxicity of DEX continued to decline during degradation processes. By QSAR predictions, the main contributors to the toxicity evolution during the UV/AOPs were predicted. Halogen-containing TPs showed significantly higher toxicity than other TPs, and thus the chlorine-containing structure in HCQ presented the potential toxicity. Appropriate reaction parameters and adequate reaction time for the UV/AOPs could eliminate the toxicity of TPs and ensure environmental safety. This study could play a positive role in the treatment of anti-COVID-19 drugs and their environmental hazard assessment. [Display omitted] • Decomposition kinetics and optimal reaction conditions during UV/AOPs for anti-COVID-19 drugs. • 24 TPs and degradation pathways were proposed by DFT and QTOF. • Toxicity data of RDV in QSAR was supplemented by luminescent bacterial test. • Combined QSAR prediction, luminescent bacterial tests and TPs peak area evolution to analyze TPs' toxicity. • Halogen groups contributed to the TPs' toxicity of HCQ. [ABSTRACT FROM AUTHOR]

This study aimed to achieve toxicity control of sulfadiazine (SDZ) and pirimiphos-methyl (PMM) via the UV/H 2 O 2 process by optimizing the reaction parameters. The results show that both drugs had a good degradation effect under the following parameters: a H 2 O 2 molar ratio of 1:200, and neutral conditions. SDZ and PMM could be degraded by more than 99% within 3 min, respectively. In the Daphnia magna acute toxicity assay and Vibrio fischeri inhibition assay, both SDZ and PMM exhibited a phenomenon of increasing toxicity. Additionally, through the use of density functional theory (DFT) calculation and HPLC-QTOF-MS, 21 transformation products (TPs) were identified, and the principal degradation pathways were proposed. The toxicity of the TPs was determined by comparing the QSAR prediction results with toxicity test data. As a result, under the higher UV light intensity (2300 μW/cm2) and neutral conditions, SDZ showed highest toxicity, whereas PMM showed lowest toxicity under the lowest UV light intensity (450 μW/cm2) and neutral conditions. Four main toxic TPs were identified, and their yields could be reduced by adjusting the reaction parameters. Therefore, the selection of appropriate reaction parameters could reduce the production of toxic TPs and ensure the safety of water environment. [Display omitted] • Toxicity of SDZ and PMM was assessed by Daphnia magna and Vibrio fischeri. • 21 TPs and degradation pathways were proposed by DFT and QTOF. • Nitrogenous groups were potential contributors to the TPs' toxicity in SDZ and PMM. • Eliminating 4 toxicity-causing TPs was verified to be effective for toxicity control. [ABSTRACT FROM AUTHOR]

The serious durability concerns of carbon supported Pt electrocatalysts for oxygen reduction reaction (ORR) have strictly limited the commercialization of fuel cells. Herein, cable-like carbon nanotubes (CNTs)@SnO 2 core@shell supports with regulable electronic metal-support interaction (EMSI) are designed for Pt nanoparticles (NPs) as ORR catalysts. Impressively, the best-performing Pt-CNT@SnO 2 catalyst with optimized d- band center achieves an excellent activity (mass activity (MA) of 0.68 A mg Pt −1 at 0.9 V iR-free and peak power density of 1618 mW cm−2) and record-high durability in H 2 -O 2 fuel cells (9.2 % MA and 8 % power density loss after 5k cycles under 1.0–1.5 V) among the reported Pt-based catalysts, which is also superior to the U.S. DOE 2025 targets. Density functional theory (DFT) calculations reveal that the strong metal-support bonding interaction (SMSBI) endows much larger adhesion energy and migration barrier towards Pt atoms compared to carbon supports, leading to the extraordinarily high stability in fuel cells. [Display omitted] • The Pt-CNT@SnO 2 catalyst demonstrates the best stability among reported Pt-based ORR catalysts under high potential regions. • Strong metal-support bonding interaction (SMSBI) between Pt and SnO 2 is able to stabilize Pt NPs against migration/agglomeration. • The d -band center of Pt is optimized by regulating the electronic metal-support interaction (EMSI). [ABSTRACT FROM AUTHOR]