Unveiling the Quantitative Relationships between Electron Distribution and Steric Hindrance of Organic Amines and Their Reaction Rates with Carbonyl Sulfur: A Theoretical Calculation Investigation.

The removal of carbonyl sulfide (COS) commonly contained in natural gas is of great significance but still very challenging via a widely employed absorption process due to its low reactivity and solubility in various commercial solvents. Artificial intelligence (AI) is playing an increasingly important role in the exploration of desulfurization solvents. However, practically feasible AI models still lack a thorough understanding of the reaction mechanisms. Machine learning (ML) models established on chemical mechanisms exhibit enhanced chemical interpretability and prediction performance. In this study, we constructed a series of solvent molecules with varying functional groups, including linear aliphatic amines, cyclic aliphatic amines, and aromatic amines and proposed a three-step reaction pathway to dissect the effects of charge and steric hindrance of different substituents on their reaction rates with COS. Chemical descriptors, based on electrostatic potential (ESP), average local ionization energy (ALIE) theory, Hirshfeld charges, and Fukui functions, were used to correlate and predict the electrophilic reactivity of amine groups with COS. Substituents influence the reaction rate by changing the attraction interaction of amine groups to COS molecules and the electron rearrangement in the electrophilic reaction. Furthermore, they have more pronounced steric effects on the reaction rate in the linear amines. The descriptors N_ALIE and q(N) were found to be crucial in predicting the reactivity of amine groups with COS. Present study provides a comprehensive understanding of the reaction mechanisms of COS with amine compounds, offers specific chemical principles for the development of chemistry-driven ML models, sheds light on other types of electrophilic reactions occurring on amine and phosphine groups, and guides the development of chemical solvents in gas absorption processes.

Chlorine-Coordinated Pd Single Atom Enhanced the Chlorine Resistance for Volatile Organic Compound Degradation: Mechanism Study.

The development of catalysts with high chlorine resistance for volatile organic compound (VOC) degradation is of great significance to achieve air purification. Herein, Pd@ZrO2 catalysts with monodispersed Pd atoms coordinated with Cl were prepared using an in situ grown Zr-based metal-organic framework (MOF) as the sacrifice templates to enhance the chlorine resistance for VOC elimination. The residual Cl species from the Zr-MOF coordinated with Pd, forming Pd1-Cl species during the pyrolysis. Meanwhile, abundant oxygen vacancies (VO) were generated, which enhanced the adsorption and activation of gaseous oxygen molecules, accelerating the degradation of VOCs. In addition, the Pd@ZrO2 catalysts exhibited satisfactory water resistance, long-term stability, and great resistance to CO and dichloromethane (DCM) for VOC elimination. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results elucidated that the generation of Pd1-Cl species in Pd@ZrO2 suppressed the absorption of DCM, releasing more active sites for toluene and its intermediate adsorption. Simultaneously, the monodispersed Pd atoms and VO improved the reactivity of gaseous oxygen molecule adsorption and dissociation, boosting the deep decomposition of toluene and its intermediates. This work may provide a new strategy for rationally designing high-chlorine resistance catalysts for VOC elimination to improve the atmospheric environment.

Divergent prokaryotic microbial assembly, co-existence patterns and functions in surrounding river sediments of a Cu-polymetallic deposit in Tibet.

The exploitation of polymetallic deposits produces large amounts of mine drainage, which poses great challenges to the surrounding aquatic ecosystem. However, the prokaryotic microbial community assembly and co-existence patterns in the polluted area are poorly understood, especially in high-altitude localities. Herein, we investigated the prokaryotic microbial assembly, co-existence patterns and their potential functional responses in surrounding river sediments of a Cu-polymetallic deposit in Tibet. The sediments from mine drainage and surrounding tributaries exhibited distinct geochemical gradients, especially the changes in Cu content. The microbial community structure changed significantly, accompanied by decreased richness and diversity with increased Cu content. Interestingly, the relative abundances of some potential functional bacteria (e.g., Planctomycetota) actually increased as the Cu levels raised. In low contaminated area, ecological drift was the most important assembly process, whereas deterministic processes gained importance with pollution levels. Meanwhile, negative interactions in co-occurrence networks were more frequent with higher modularity and reduced keystone taxa in high contaminated area. Notably, the functions related to ABC transporters and quorum sensing (QS) were more abundant with high Cu content, which helped bacteria work together to cope with the stressful environment. Taken together, the physicochemical gradients dominated by Cu content drove the distribution, assembly and co-existence patterns of microbial communities in surrounding river sediments of a Cu-polymetallic deposit. These findings provide new insights into the maintenance mechanisms of prokaryotic microbial communities in response to heavy metal stress at high altitudes.

N, P Codoped Hollow Carbon Nanospheres Decorated with MoSe2 Ultrathin Nanosheets for Efficient Potassium-Ion Storage.

Potassium-ion batteries (KIBs) are gradually being considered as an alternative for lithium-ion batteries because of their non-negligible advantages such as abundance and low expenditure of K, as well as higher electrochemical potential than another alternative─sodium-ion batteries. Nevertheless, when the electrode materials are inserted and extracted with large-sized K+ ions, the tremendous volume change will cause the collapse of the microstructures of electrodes and make the charging/discharging process irreversible, thus disapproving their extended application. In response to this, we put forward a feasible strategy to realize the in situ assembly of layered MoSe2 nanosheets onto N, P codoped hollow carbon nanospheres (MoSe2/NP-HCNSs) through thermal annealing and heteroatom doping strategies, and the resulting nanoengineered material can function well as an anode for KIBs. This cleverly designed nanostructure of MoSe2/NP-HCNS can broaden the interlayer spacing of MoSe2 to boost the efficiency of the insertion/extraction of K ions and also can accommodate large volume change-caused mechanical strain, facilitate electrolyte penetration, and prevent the aggregation of MoSe2 nanosheets. This synthetic method generates abundant defects to increase the amounts of active sites, as well as conductivity. The hierarchical nanostructure can effectively increase the proportion of pseudo-capacitance and promote interfacial electronic transfer and K+ diffusion, thus imparting great electrochemical performance. The MoSe2/NP-HCNS anode exhibits a high reversible capacity of 239.9 mA h g-1 at 0.1 A g-1 after 200 cycles and an ultralong cycling life of 161.1 mA h g-1 at 1 A g-1 for a long period of 1000 cycles. This nanoengineering method opens up new insights into the development of promising anode materials for KIBs.

Mesoporous structure and amorphous Fe-N sites regulation in Fe-g-C3N4 for boosted visible-light-driven photo-Fenton reaction.

Heterogeneous photo-Fenton catalysts prepared by doping metal ions in g-C3N4 are promising alternatives to traditional homogeneous Fenton catalysts, but are restricted by poor mesoporous structure and agglomerate of metal species. Recently, the highly uniformly dispersed metal-N active sites in various photocatalysts have been proved to be the critical reason for their enhanced catalytic activity. In this study based on reasonable control of mesoporous structure and metal-N active sites, mesoporous Fe-g-C3N4 was synthesized using a simple one-step thermal shrinkage polymerization method using ferrous oxalate as iron source and pore-forming agent. The Fe and N elements in the triazine ring skeleton of Fe-g-C3N4 form a σ-π bond, thus the photogenerated electrons can be quickly transferred to Fe3+ to form Fe2+ under the interaction of chemical bonds, accelerating the Fenton reaction rate. Density functional theory calculations results demonstrate that the energy band structure and electron cloud density distribution of Fe-Nx active structure are better than that of routine FeOx crystal structure with metal species agglomeration. In addition, the excellent mesoporous structure of Fe-g-C3N4 creates conditions for the high exposure of Fe-Nx active sites in the photo-Fenton reaction under visible light. The as-developed Fe-g-C3N4 system shows high recyclability and excellent photo-Fenton performance for removal of typical intractable pollutants (The degradation rate of dye and tetracycline reaches 98.2% and 98.7% at 60 and 120 min, respectively). This work provides a facile and sustainable route to develop mesoporous highly-active heterogeneous Fenton-like catalysts and even further general the design of general catalyst with ideal metal-N active sites, thereby promoting a feasible and efficient wastewater remediation solution.

Boosting potassium-ion storage in large-diameter carbon nanotubes/MoP hybrid.

Potassium-ion batteries (KIBs) as a substitute for lithium ion batteries have attracted tremendous attention in recent years thanks to the cost-effectiveness and abundance of potassium resources. However, the current lack of suitable electrode materials is a major obstacle against the practical application of KIBs. Hence, design and preparation of capable anode materials are critical for the development of KIBs. In this study, a promising electrode based on N, P-codoped large diameter hollow carbon nanotubes decorated with ultrasmall MoP nanoparticles (MoP@NP-HCNTs) were prepared. The hollow carbon nanotubes facilitate the rapid electron and ion transfer, and release the huge volume expansion during discharge/charge. The MoP@NP-HCNT electrode delivers high initial capacity of 485, 482 and 463 mAh g-1 corresponding to 100, 200 and 1000 mA g-1, respectively. The discharge specific capacity still maintains 300 mAh g-1 at 100 mA g-1 after over 80 cycles. It still shows ultralong cycling stability with a discharge capacity of 255 mAh g-1 at a high current density of 1000 mA g-1 after 120 cycles. This study opens up a new routine to develop high reversible capacity and promising electrode materials for KIBs.