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[Display omitted] • RuO 2 (1 1 0) surface is reported as an active catalyst for ethylene production from methane. • Diffusion of intermediates and ethylene desorption on RuO 2 (1 1 0) surface are facile. • The temperature of catalytic conversion of methane can be remarkably low as 200 K. • 100 % ethylene selectivity could be reached at low temperatures (300 – 450 K). Despite significant progress in low-temperature methane (CH 4) activation, commercial viability, specifically obtaining high yields of C 1 /C 2 products, remains a challenge. High desorption energy (>2 eV) and overoxidation of the target products are key limitations in CH 4 utilization. Herein, we employ first-principles density functional theory (DFT) and microkinetics simulations to investigate the CH 4 activation and the feasibility of its conversion to ethylene (C 2 H 4) on the RuO 2 (1 1 0) surface. The C H activation and CH 4 dehydrogenation processes are thoroughly investigated, with a particular focus on the diffusion of surface intermediates. The results show that the RuO 2 (1 1 0) surface exhibits high reactivity in CH 4 activation (E a = 0.60 eV), with CH 3 and CH 2 are the predominant species, and CH 2 being the most mobile intermediate on the surface. Consequently, self-coupling of CH 2 * species via C C coupling occurs more readily, yielding C 2 H 4 , a potential raw material for the chemical industry. More importantly, we demonstrate that the produced C 2 H 4 can easily desorb under mild conditions due to its low desorption energy of 0.97 eV. Microkinetic simulations based on the DFT energetics indicate that CH 4 activation can occur at temperatures below 200 K, and C 2 H 4 can be desorbed at room temperature. Further, the selectivity analysis predicts that C 2 H 4 is the major product at low temperatures (300–450 K) with 100 % selectivity, then competes with formaldehyde at intermediate temperatures in the CH 4 conversion over RuO 2 (1 1 0) surface. The present findings suggest that the RuO 2 (1 1 0) surface is a potential catalyst for facilitating ethylene production under mild conditions. [ABSTRACT FROM AUTHOR]

Construction resting on soil and rocks containing montmorillonite (MMT) are prone to damage induced by swelling, which involves a significant release of energy. It is often desirable to enhance these soils to mitigate swelling potential, regulate volume changes, and manage energy release. Experimental findings suggest that increasing temperature is one method to improve these soils, with water content, initial volume, and boundary conditions also influencing the swelling mechanism. This study utilizes ab initio molecular dynamics calculations to explore changes in volume and energy within MMT unit cells at the nanoscale due to temperature variations. The response of unit cells of MMT with varying dimensions and quantities of water molecules to temperature is assessed under constrained and unconstrained conditions. Results indicate that the volume changes and energy release of unit cells in response to temperature are contingent upon the presence of water molecules. In unit cells containing water molecules, both energy and volume decrease with rising temperature, whereas in unit cells devoid of water molecules, energy decreases while volume increases as temperature rises. Given the inherent association of soils with water in natural settings, it can be deduced that increasing temperature presents a viable method for enhancing naturally occurring MMT-dominated soils. Density functional theory calculations demonstrate that alterations in the volume and energy of MMT stem from shifts in interactions among the minerals, cations, and water molecules, as well as intrinsic structural defects like isomorphic substitution and peroxy links within the unit cells. These modifications induce variations in charge carriers and electrical properties, consequently influencing volume and energy changes within MMT unit cells. Additionally, it was observed that the failure of peroxy links can significantly impact the optimal temperature selection for the thermal enhancement of MMT. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction to CH4 remains challenging due to multi-electron transfer and intermediates adsorption. Herein, we synthesized electrocatalysts by growing Ni-Cu alloy structure on nitrogen-doped carbon nanotubes (NixCuy-NCNT) for electrocatalytic CO2 reduction reaction (CO2RR) via hydrothermal method followed by pyrolysis. The optimized Ni1Cu1-NCNT demonstrated a superior CO2RR performance, achieving 99.7% FE CH 4 (FE = Faradaic efficiency) and 11.54 mA • cm−2 current density at −1.2 V vs. reversible hydrogen electrode (RHE), which outperformed single metal counterparts. Its outstanding performance was due to the electrons transferred from Cu to Ni and Ni-Cu alloy shifted the d-band center toward the Fermi level, which was more conducive to the intermediate formation. In situ electrochemical attenuated total reflection (EC-ATR) and density functional theory (DFT) calculations revealed the appearance of *CHO intermediate and the pathway during the CO2RR process. The design of the bimetallic electrocatalyst in this study provides a new perspective for the highly selective reduction of CO2. [ABSTRACT FROM AUTHOR]

In this study, a Mn-modified Pt-based catalyst loaded on nitrogen-doped Ketjen black (Mn-Pt/NKB) is prepared using a simple ethylene glycol reduction method. The size of Pt nanoparticles (NPs) is effectively controlled by doping with Mn and N. With the smallest average particle size of 1.7 nm, Mn-Pt/NKB demonstrates half-wave potentials of 0.890 and 0.688 V in the alkaline and neutral electrolytes, respectively, which are superior to those of commercial platinum on activated carbon (Pt/C). When applied as an air cathode in aluminum-air battery, it exhibits ultra-high power densities of 190 (alkaline) and 26.2 mW·cm−2 (neutral). Moreover, the voltage remains stable after 5 h of discharge. The practical application performance of the Mn-Pt/NKB catalyst in an aluminum-air battery is better than that of commercial Pt/C. Furthermore, the oxygen reduction reaction (ORR) mechanism on surfaces with different particle sizes is analyzed using density functional theory. Oxygen cracking is the major pathway on the surface of the small particles with lower energy consumption of 0.5 eV, while water molecule cleavage is the major pathway on the surface of the large particles with higher energy consumption of 0.97 eV. The lower energy consumption of the oxygen cracking pathway further confirms the ORR mechanism for higher activity on small-sized surfaces. This study provides a direction for the rational design of Pt-based catalysts for ORR and sheds light on the commercial development of aluminum-air batteries. [ABSTRACT FROM AUTHOR]

In this study, we present a comprehensive first-principles computational investigation focused on the structural characteristics, electronic properties, and coupling integrations of three cationic Gemini surfactants: 12-4-12, 12-3-12, and 12-2-12 ((CH3(CH2)11)(CH3)2-N+-(CH2)n-N+(CH3(CH2)11)(CH3)2, where n = 2, 3, or 4). By employing Density Functional Theory (DFT) computations, we aimed to gain insights into the fundamental aspects of these surfactant molecules, and the intermolecular interactions among these surfactant molecules. We examined different conformers of each surfactant, including parallel, wing, and bent conformers, and compared their relative stability and properties. We elucidated that the complex structural characteristics, electronic properties, and molecular arrangements of the surfactants vary according to the number of carbon atoms in the central spacer. We also conducted experimental Raman spectroscopy on the three surfactants to compare the results with our computational findings. Furthermore, we computed the coupling behaviors of different conformers of 12-4-12 surfactants in order to gain insights into their coupling mechanism. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials that combine ferromagnetic, semiconductor, and piezoelectric properties hold significant potential for both fundamental research and spin electronic devices. However, the majority of reported 2D ferromagnetic-semiconductor-piezoelectric materials rely on d-electron systems, which limits their practical applications due to a Curie temperature lower than room temperature (RT). Here, we report a high-crystallinity carbon nitride (CCN) material based on sp-electrons using a chemical vapor deposition strategy. CCN exhibits a band gap of 1.8 eV and has been confirmed to possess substantial in-plane and out-of-plane piezoelectricity. Moreover, we acquired clear evidences of ferromagnetic behavior at room temperature. Extensive structural characterizations combined with theoretical calculations reveal that incorporating structural oxygen into the highly ordered heptazine structure causes partial substitution of nitrogen sites, which is primarily responsible for generating room-temperature ferromagnetism and piezoelectricity. As a result, the strain in wrinkles can effectively modulate the domain behavior and piezoelectric potential at room temperature. The addition of RT ferromagnetic-semiconductor-piezoelectric material based on sp-electrons to the family of two-dimensional materials opens up numerous possibilities for novel applications in fundamental research and spin electronic devices. [ABSTRACT FROM AUTHOR]

This study investigates the utilisation of organometallic network frameworks composed of fourth-period transition metals and tetrahydroxyquinone (THQ) in electrocatalytic CO2 reduction. Density functional theory (DFT) calculations were employed in analysing binding energies, as well as the stabilities of metal atoms within the THQ frameworks, for transition metal TM-THQs ranging from Y to Cd. The findings demonstrate how metal atoms could be effectively dispersed and held within the THQ frameworks due to sufficiently high binding energies. Most TM-THQ frameworks exhibited favourable selectivity towards CO2 reduction, except for Tc and Ru, which experienced competition from hydrogen evolution reaction (HER) and required solution environments with pH values greater than 5.716 and 8.819, respectively, to exhibit CO2RR selectivity. Notably, the primary product of Y, Ag, and Cd was HCOOH; Mo produced HCHO; Pd yielded CO; and Zr, Nb, Tc, Ru, and Rh predominantly generated CH4. Among the studied frameworks, Zr-THQ displayed values of 1.212 V and 1.043 V, corresponding to the highest limiting potential and overpotential, respectively, while other metal–organic frameworks displayed relatively low ranges of overpotentials from 0.179 V to 0.949 V. Consequently, it is predicted that the TM-THQ framework constructed using a fourth-period transition metal and tetrahydroxyquinone exhibits robust electrocatalytic reduction of CO2 catalytic activity. [ABSTRACT FROM AUTHOR]

Carbon materials have shown significant potential as catalysts for lithium-oxygen batteries (LOBs). However, the intrinsic carbon sites are typically inert, necessitating extensive modifications and resulting in a limited density of active sites. Here we present C60 as a metal-free cathode catalyst for LOBs, using density functional theory calculations and experimental verifications. The lithiation reactions on the pristine carbon sites of C60 are energetically favorable due to its curved π-conjugation over the pentagon–hexagon networks. The kinetic analysis specifically reveals low energy barriers for Li2O2 decomposition and Li diffusion on C60. Consequently, C60 exhibits significantly higher catalytic activity than typical carbon materials such as graphene and carbon nanotubes. Our electrochemical measurements validate the predictions, notably demonstrating that the intrinsic activity of C60 is comparable to that of noble metals. [ABSTRACT FROM AUTHOR]

Reduced dithiolene ligands are bound to high valent Mo centers in the active site of the oxotransferase family of enzymes. Related model complexes have been studied with great insight by Prof. Holm and his colleagues. This study focuses on the other limit of dithiolene chemistry: an investigation of the 2-electron oxidized dithiolene bound to low-valent late transition metal (TM) ions (ZnII, CuI, and CuII). The bonding descriptions of the oxidized dithiolene [N,N-dimethyl piperazine 2,3-dithione (Me2Dt0)] complexes are probed using S K-edge X-ray absorption spectroscopy (XAS) and the results are correlated to density functional theory (DFT) calculations. These experimentally supported calculations are then extended to explain the different geometric structures of the three complexes. The ZnII(Me2Dt0)2 complex has only ligand-ligand repulsion so it is stabilized at the D2d symmetry limit. The CuI(Me2Dt0)2 complex has additional weak backbonding thus distorts somewhat from D2d toward D2h symmetry. The CuII(Me2Dt0)2 complex has a strong σ donor bond that leads to both a large Jahn-Teller stabilization to D2h and an additional covalent contribution to the geometry. The combined strong stabilization results in the square planar, D2h structure. This study quantifies the competition between the ligand-ligand repulsion and the change in electronic structures in determining the final geometric structures of the oxidized dithiolene complexes, and provides quantitative insights into the Jahn-Teller stabilization energy and its origin.

Selenium (Se) isotopes have recently emerged as a potential proxy for tracing biogeochemical processes and reconstructing the evolution of global Se cycle in the oceans. However, little is known about Se isotope fractionation mechanism during the sequestration of dissolved Se oxyanions by marine ferromanganese oxides that are mainly composed of Fe and Mn (oxyhydr)oxides. Here we elucidate the molecular mechanism governing equilibrium Se isotope fractionation during adsorption on 2-line ferrihydrite, by combining isotope ratio measurements, extended X-ray absorption fine structure (EXAFS) analyses, and high level quantum chemical calculations. Results show that Se isotopes can be fractionated 0.89‰ (Δ82/76Se aqueous-adsorbed) with enrichment of lighter isotopes in the solid phase during the adsorption of Se(IV) on 2-line ferrihydrite, which is primarily driven by the formation of bidentate-binuclear inner-sphere complexes. By contrast, little or no Se isotope fractionation (<0.2‰) was observed during Se(VI) adsorption due to the outer-sphere complexation. In combination with previous results, our findings would provide molecular-scale insights into Se isotope compositions in marine ferromanganese oxides and lead to an improved understanding of Se biogeochemical cycle in the ocean. Our study also has an implication for the systematical understanding of mechanisms governing isotope fractionations of other metal oxyanions like Mo, which highlights the controls of their proton dissociation constants, electronic configurations, and radius ratios. This would improve our understanding for isotope signatures of metals in the dissolved species and the adsorbed sinks in modern and ancient environments. [ABSTRACT FROM AUTHOR]

The growing demand for lithium, which is essential for the production of batteries, has led to a significant rise in the price of lithium. The quest for novel materials that could enhance battery performance has thus become a key challenge for scientists. In this regard, the author conducted a comparative analysis of materials based on graphene, using density functional theory and ab initio molecular dynamics methods. The materials considered for comparison include graphene, C3B, and C3N. For the calculations, two-layer systems of pristine graphene and graphene modified by substituting carbon atoms with boron and nitrogen were constructed. The stability of these systems was examined using the Quantum Espresso and CP2K software at 0 K and 300 K, respectively. In the search for an alternative to lithium, systems incorporating sodium and lithium intercalated between graphene layers were also included in the comparison. [ABSTRACT FROM AUTHOR]

In this study, we present a comprehensive first-principles computational investigation focused on the structural characteristics, electronic properties, and coupling integrations of three cationic Gemini surfactants: 12-4-12, 12-3-12, and 12-2-12 ((CH3(CH2)11)(CH3)2-N+-(CH2)n-N+(CH3(CH2)11)(CH3)2, where n = 2, 3, or 4). By employing Density Functional Theory (DFT) computations, we aimed to gain insights into the fundamental aspects of these surfactant molecules, and the intermolecular interactions among these surfactant molecules. We examined different conformers of each surfactant, including parallel, wing, and bent conformers, and compared their relative stability and properties. We elucidated that the complex structural characteristics, electronic properties, and molecular arrangements of the surfactants vary according to the number of carbon atoms in the central spacer. We also conducted experimental Raman spectroscopy on the three surfactants to compare the results with our computational findings. Furthermore, we computed the coupling behaviors of different conformers of 12-4-12 surfactants in order to gain insights into their coupling mechanism.

This study investigates the utilisation of organometallic network frameworks composed of fourth-period transition metals and tetrahydroxyquinone (THQ) in electrocatalytic CO2 reduction. Density functional theory (DFT) calculations were employed in analysing binding energies, as well as the stabilities of metal atoms within the THQ frameworks, for transition metal TM-THQs ranging from Y to Cd. The findings demonstrate how metal atoms could be effectively dispersed and held within the THQ frameworks due to sufficiently high binding energies. Most TM-THQ frameworks exhibited favourable selectivity towards CO2 reduction, except for Tc and Ru, which experienced competition from hydrogen evolution reaction (HER) and required solution environments with pH values greater than 5.716 and 8.819, respectively, to exhibit CO2RR selectivity. Notably, the primary product of Y, Ag, and Cd was HCOOH; Mo produced HCHO; Pd yielded CO; and Zr, Nb, Tc, Ru, and Rh predominantly generated CH4. Among the studied frameworks, Zr-THQ displayed values of 1.212 V and 1.043 V, corresponding to the highest limiting potential and overpotential, respectively, while other metal–organic frameworks displayed relatively low ranges of overpotentials from 0.179 V to 0.949 V. Consequently, it is predicted that the TM-THQ framework constructed using a fourth-period transition metal and tetrahydroxyquinone exhibits robust electrocatalytic reduction of CO2 catalytic activity.

Very recently, much research progress has been made on the pressure‐induced superconducting state in ternary hydrides. Herein, an ab initio study of the KC2H8 ternary system is presented at a pressure in the range of 0–100 GPa. Its structural, electronic, dynamical, and superconducting properties are investigated, demonstrating that, at low pressure, KC2H8 is dynamically stable in a clathrate structure with space group Fm3¯$\bar{3}$m and exhibits superconducting behavior with critical temperatures Tc in the range of 4–94 K. The important role played by C‐ and K‐derived phonon modes at low frequencies and H‐derived phonon modes at high frequencies is highlighted. Moreover, through the analysis of the hydrogen isotope effect, the conventional phonon‐mediated pairing mechanism in this system is proved. [ABSTRACT FROM AUTHOR]

We studied the adsorption and reaction behavior of the ionic liquid (IL) 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im][Tf2N]) on Cu(111) using non-contact atomic force microscopy (nc-AFM), scanning tunneling microscopy (STM), and angle-resolved X-ray photoelectron spectroscopy (ARXPS) in ultrahigh vacuum as a function of temperature, supported by density-functional theory (DFT) calculations. Our nc-AFM results for sub-monolayer IL films show that at 200 K, the IL self-assembles into highly ordered islands, with cations and anions arranged next to each other in a checkerboard–type phase. After extended annealing at 300 K, the structure transforms first to a hexagonal phase and then to a porous honeycomb phase. Simultaneously, many small, disordered islands are formed. Complementary ARXPS reveals no IL desorption until 300 K. However, a significant fraction of the IL is converted to a new species as deduced from new, strongly shifted peaks that develop in the XP spectra at around 275 K and grow with annealing time at 300 K. We correlate the remaining unshifted peaks to the ordered phases observed in nc-AFM and the shifted peaks to decomposition products, which appear as disordered islands in nc-AFM and STM. Upon further heating to 360 K, about 50% of the anions or their decomposition products desorb from the surface, while cation-related fragments mostly remain on the surface. From DFT, we obtain additional information on the structure of the ordered phases and the interaction of the IL with the substrate. [ABSTRACT FROM AUTHOR]

Electrochemical nitrate reduction reaction (NtrRR) has been emerging as an appealing route for both water treatment and NH3 synthesis. Herein, we report the structure analysis and electrocatalytic performance of a novel homoleptic alkynyl-protected Ag20Cu12 nanocluster (Ag20Cu12 in short) with atomic precision, which has eight free electrons and displays characteristic absorbance feature. Single crystal X-ray diffraction (SC-XRD) discloses that, it adopts a Ag14 kernel capped by three Ag2Cu4(C≡CArF)8 metal–ligand binding motifs in the outer shell. Ag20Cu12 exhibited excellent catalytic performance toward NtrRR, as manifested by the superior NH3 Faradaic efficiency (FE, 84.6%) and yield rate (0.138 mmol·h−1·mg−1) than the homoleptic alkynyl-protected Ag32 nanoclusters. Additionally, it demonstrates good catalytic recycling capability. Density functional theory (DFT) calculations revealed that, the de-ligated Ag20Cu12 cluster can expose the available AgCu bimetallic sites as the efficient active sites for NH3 formation. In particular, the participation of Cu sites greatly facilitates the initial capture of NO3− and simultaneously promotes the selectivity of the final product. This study discovers a novel homoleptic alkynyl-protected AgCu superatom, and offers a great example to elucidate the structure–performance relationship of bimetallic catalyst for NtrRR and other multiple protons/electrons coupled electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

Zigzag graphene nanoribbons (ZGNRs) with spin-polarized edge states have potential applications in carbon-based spintronics. The electronic structure of ZGNRs can be effectively tuned by different widths or dopants, which requires delicately designed monomers. Here, we report the successful synthesis of ZGNR with a width of eight carbon zigzag lines and nitrogen-boron-nitrogen (NBN) motifs decorated along the zigzag edges (NBN-8-ZGNR) on Au (111) surface, which starts from a specially designed U-shaped monomer with preinstalled NBN units at the zigzag edge. Chemical-bond-resolved non-contact atomic force microscopy (nc-AFM) imaging confirms the zigzag-terminated edges and the existence of NBN dopants. The electronic states distributed along the zigzag edges have been revealed after a silicon-layer intercalation at the interface of NBN-8-ZGNR and Au (111). Our work enriches the ZGNR family with a new dopant and larger width, which provides more candidates for future carbon-based nanoelectronic and spintronic applications. [ABSTRACT FROM AUTHOR]

Infrared (IR) thermal imaging is receiving a great deal of attention due to its wide range of applications. Given multiple issues (like cost and availability) with the inorganic materials currently exploited for IR imaging, there is nowadays a great push of developing organic imaging materials. Carbon‐based materials are known to have significant transparency in the visible and IR regions and some are used as transparent conductors. Here, whether π‐conjugated carbon‐based materials are suitable for long‐wave (LW) and mid‐wave (MW) IR imaging applications is computationally assessed. Using density functional theory calculations, the IR‐vibrational properties of molecules from acenes to coronenes and fullerenes, and of periodic systems like graphene and carbon nanotubes are characterized. Fullerenes, graphenes, and double‐walled carbon nanotubes are found to be very attractive as they are transparent in both the LWIR and MWIR regions, a feature resulting from the absence of hydrogen atoms. Also, it is found that replacing hydrogen atoms in a molecule with deuterium or sulfur atoms can be an efficient way to improve their LWIR or MWIR transparency, respectively. For fused‐ring systems having hydrogen atoms on the periphery, designing molecules with trio CH‐units is another way to enhance the transparency in the LWIR region. [ABSTRACT FROM AUTHOR]

Ethane dehydrogenation (EDH) to produce ethylene requires high operating temperature to achieve satisfactory ethylene yield, however, this process leads to coke formation and catalyst deactivation. Here, an active site isolation strategy was employed to inhibit side reaction and coke formation over fifteen types of metal single-atom metal/graphitic carbon nitride (M/g-C3N4) catalysts. Density functional theory (DFT) calculations completely describe reaction network of ethane dehydrogenation. On-lattice kinetic Monte Carlo simulations were carried out to evaluate catalytic performance under the realistic conditions. The Co/g-C3N4, Rh/g-C3N4, and Ni/g-C3N4 catalysts were screened out to exhibit higher C2H4(g) formation activity and C2H4(g) selectivity close to or equal to 100%. The low reactant partial pressure 0%–5% at atmospheric pressure facilitates ethane dehydrogenation, and the appropriate temperatures over Co/g-C3N4, Rh/g-C3N4, and Ni/g-C3N4 catalysts are 673.15, 723.15, and 723.15 K, respectively. Especially, Co/g-C3N4 catalyst presents the highest C2H4(g) formation activity, attributing to the appropriate anti-bonding strength between C atom and metal single-atom. Further, a simple descriptor, the reaction energy of C2H5* dehydrogenation to C2H4*, was proposed to quantitatively and quickly evaluate C2H4(g) formation activity. The present study laid a solid foundation for efficient design and development of single-atom catalysts with high-performance for selective dehydrogenation of alkanes. [ABSTRACT FROM AUTHOR]

Enabling long cyclability of high-voltage oxide cathodes is a persistent challenge for all-solid-state batteries, largely because of their poor interfacial stabilities against sulfide solid electrolytes. While protective oxide coating layers such as LiNbO3 (LNO) have been proposed, its precise working mechanisms are still not fully understood. Existing literature attributes reductions in interfacial impedance growth to the coating's ability to prevent interfacial reactions. However, its true nature is more complex, with cathode interfacial reactions and electrolyte electrochemical decomposition occurring simultaneously, making it difficult to decouple each effect. Herein, we utilized various advanced characterization tools and first-principles calculations to probe the interfacial phenomenon between solid electrolyte Li6PS5Cl (LPSCl) and high-voltage cathode LiNi0.85Co0.1Al0.05O2 (NCA). We segregated the effects of spontaneous reaction between LPSCl and NCA at the interface and quantified the intrinsic electrochemical decomposition of LPSCl during cell cycling. Both experimental and computational results demonstrated improved thermodynamic stability between NCA and LPSCl after incorporation of the LNO coating. Additionally, we revealed the in situ passivation effect of LPSCl electrochemical decomposition. When combined, both these phenomena occurring at the first charge cycle result in a stabilized interface, enabling long cyclability of all-solid-state batteries.

The irradiation of 2-aryl-4-(E-3′-aryl-allylidene)-5(4H)-oxazolones 1 with blue light (456 nm) in the presence of [Ru(bpy)3](BF4)2 (bpy = 2,2′-bipyridine, 5% mol) gives the unstable cyclobutane-bis(oxazolones) 2 by [2+2]-photocycloaddition of two oxazolones 1. Each oxazolone contributes to the formation of 2 with a different C=C bond, one of them reacting through the exocyclic C=C bond, while the other does so through the styryl group. Treatment of unstable cyclobutanes 2 with NaOMe/MeOH produces the oxazolone ring opening reaction, affording stable styryl-cyclobutane bis(amino acids) 3. The reaction starts with formation of the T1 excited state of the photosensitizer 3[Ru*(bpy)3]2+, which reacts with S0 of oxazolones 1 through energy transfer to give the oxazolone T1 state 3(oxa*)-1, which is the reactive species and was characterized by transient absorption spectroscopy. Measurement of the half-life of 3(oxa*)-1 for 1a, 1b and 1d shows large values for 1a and 1b (10–12 μs), while that of 1d is shorter (726 ns). Density functional theory (DFT) modeling displays strong structural differences in the T1 states of the three oxazolones. Moreover, study of the spin density of T1 state 3(oxa*)-1 provides clues to understanding the different reactivity of 4-allylidene-oxazolones described here with respect to the previously reported 4-arylidene-oxazolones. [ABSTRACT FROM AUTHOR]

2D materials have raised a lot of interest in the last decades, due to their novel and diverse properties, particularly for energy technology applications where materials such as molybdenum disulfide are known for their outstanding catalytic ability. While intensive research is devoted to 2D transition metal dichalcogenide (TMDCs) semiconductor characterization, comprehensive understanding of metal/semiconductor heterojunctions is still lacking especially for junctions containing 2D metallic monolayers other than graphene. Using wave‐packet propagation, charge transport of two electrons through heterojunctions is simulated, in order to assess the influence of the electron–electron interaction on the charge transport efficiency. TMDCs with similar structure for both metal and semiconductor monolayers are used, leading to a high‐quality metal contact. It is found that charge transport is more efficient in systems containing a chromium disulfide semiconductor monolayer compared to systems with MoS2 or tungsten disulfide. This trend in the efficiency is the same with and without electron–electron interaction, demonstrating the validity of the qualitative input provided by models that lack electron–electron interactions. Nevertheless, for all systems, the interaction increases charge transmission probability from the metal to the semiconductor, due to electronic repulsion that pushes one of the charge carriers forward across the interface. [ABSTRACT FROM AUTHOR]

Renewable energy powered electrocatalytic water splitting is a promising strategy for hydrogen generation, and the design and development of high-efficiency and earth-abundant electrocatalysts for hydrogen evolution reaction (HER) are highly desirable. Herein, MoS2 nanoflowers decorated two-dimensional carbonitride-based MXene Ti3CN(OH)x hybrids have been constructed by etching and post-hydrothermal methods. The electrochemical performance of the as-obtained Ti3CN(OH)x@MoS2 hybrids having a quasi core—shell structure is fascinating: An overpotential of 120 mV and a Tafel slope of 64 mV·dec−1 can be delivered at a current density of 10 mA·cm−2. And after 3,000 cyclic voltammetry cycles, it can be seen that there is no apparent attenuation. Both the experimental results and density functional theory (DFT) calculations indicate that the synergetic effects between Ti3CN(OH)x and MoS2 are responsible for the robust electrochemical HER performance. The electrons of −OH group in Ti3CN(OH)x are transferred to MoS2, making the adsorption energy of the composite for H almost vanish. The metallic Ti3CN(OH)x is also beneficial to the fast charge transfer kinetics. The construction of MXene-based hybrids with optimal electronic structure and unique morphology tailored to the applications can be further used in other promising energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

Herein, a mechanism is proposed as to how thin films formed from a Heusler compound can simultaneously have both perpendicular magnetic anisotropy (PMA) and be half‐metallic. It is proposed that a thin film formed from a half‐metallic full‐Heusler or half‐Heusler compound that is cubic in the bulk can undergo a tetragonal distortion by adopting the lattice constant of the underlayer material during the thin film deposition process. The value of this distortion can be tuned by using underlayer materials with different in‐plane lattice constants. The distortion can thereby be optimized so that it is large enough to give rise to sufficient PMA, while, simultaneously, small enough to retain the half‐metallic properties (and, therefore, high tunneling magnetoresistance properties) of the Heusler compound. Density functional theory (DFT) calculations that are carried out for 90 full‐Heuslers and 147 half‐Heuslers that have been identified in the literature as half‐metals show that of these, 14 full‐Heusler and 59 half‐Heusler compounds display both half‐metallicity and PMA for optimal tetragonal distortions. [ABSTRACT FROM AUTHOR]

The aromatic C(sp2)-H functionalization of unprotected naphthols with α-phenyl-α-diazoesters under mild conditions catalyzed by CuCl and CuCl2 exhibits high efficiency and unique ortho-selectivity. In this study, the combination of density functional theory (DFT) calculations and experiments is employed to investigate the mechanism of C-H functionalization, which reveals the fundamental origin of the site-selectivity. It explains that CuCl-catalyzed ortho-selective C-H functionlization is due to the bimetallic carbene, which differs from the reaction catalyzed by CuCl2 via monometallic carbene. The results demonstrate the function of favourable H-bond interactions on the site- and chemo-selectivity of reaction through stabilizing the rate-determining transition states in proton (1,3)-migration. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, and optical properties of Co‐ and Mn‐adsorbed γ‐GeSe have been studied comprehensively via first‐principles density functional calculations. It is found that the most stable adsorption configuration is that Co and Mn are on the top of the hexagonal hollow in the second Ge layer. After Co and Mn adsorption, γ‐GeSe becomes magnetic with 1 μB and 3 μB magnetic moment, which mainly comes from mainly the Co(Mn)‐d, Ge‐s, Ge‐p, and Se‐p states. In particular, the optical absorption in the low‐energy range is greatly enhanced by Co and Mn adsorption and results in interesting spin‐dependent absorption in low‐energy region due to the strong electron transition at the spin‐down channel, which makes them attractive candidates for spin‐optoelectronic devices. [ABSTRACT FROM AUTHOR]

Interactions between negatively charged aluminosilicate species and positively charged metal cations are critical to many important engineering processes and applications, including sustainable cements and aluminosilicate glasses. In an effort to probe these interactions, here we have calculated the pair-wise interaction energies (i.e., binding energies) between aluminosilicate dimer/trimer and 17 different metal cations Mn+ (Mn+ = Li+, Na+, K+, Cu+, Cu2+, Co2+, Zn2+, Ni2+, Mg2+, Ca2+, Ti2+, Fe2+, Fe3+, Co3+, Cr3+, Ti4+ and Cr6+) using a density functional theory (DFT) approach. Analysis of the DFT-optimized structural representations for the clusters (dimer/trimer + Mn+) shows that their structural attributes (e.g., interatomic distances) are generally consistent with literature observations on aluminosilicate glasses. The DFT-derived binding energies are seen to vary considerably depending on the type of cations (i.e., charge and ionic radii) and aluminosilicate species (i.e., dimer or trimer). A survey of the literature reveals that the difference in the calculated binding energies between different Mn+ can be used to explain many literature observations associated with the impact of metal cations on materials properties (e.g., glass corrosion, mineral dissolution, and ionic transport). Analysis of all the DFT-derived binding energies reveals that the correlation between these energy values and the ionic potential and field strength of the metal cations are well captured by 2nd order polynomial functions (R2 values of 0.99–1.00 are achieved for regressions). Given that the ionic potential and field strength of a given metal cation can be readily estimated using well-tabulated ionic radii available in the literature, these simple polynomial functions would enable rapid estimation of the binding energies of a much wider range of cations with the aluminosilicate dimer/trimer, providing guidance on the design and optimization of sustainable cements and aluminosilicate glasses and their associated applications. Finally, the limitations associated with using these simple model systems to model complex interactions are also discussed.

Highly efficient electrochemical water splitting is of prime importance in hydrogen energy but is suffered from the slow kinetics at the anodic oxygen evolution reaction. Herein, combining the surface activation with the heterostructure construction strategy, the CoP/Fe‐Co9S8 heterostructures as the pre‐catalyst for highly efficient oxygen evolution are successfully synthesized. The catalyst only needs 156 mV to reach 10 mA cm−2 and keeps stable for more than 150 h. Inductively coupled plasma optical emission spectrometry, in situ Raman spectroscopy and density functional theory calculations verify that the introduction of Fe can promote the formation of highly active Co(IV)–O sites and lead to a self‐termination of surface reconstruction, which eventually creates a highly active and stable oxygen evolution catalytic surface. Besides, the catalyst also demonstrates high hydrogen evolution reaction activity with an overpotential of 62 mV@10 mA cm−2. Benefiting from its bifunctionality and self‐supporting property, the membrane electrode assembly electrolyzer equipped with these catalysts achieves high overall water splitting efficiency of 1.68 V@1 A cm−2. [ABSTRACT FROM AUTHOR]

The paper presents research on chloride minerals of natural origin from Kłodawa (Poland), i.e., colorless, blue and purple halite as well as colorless sylvite. Selected samples of minerals were studied by chemical analysis (ICP-OES, ICP-MS, titration methods) and crystallographic measurements. Then, for the tested halides, research was carried out using far-infrared spectroscopy. Spectroscopic studies confirmed the simple way of distinguishing NaCl and KCl minerals using far-infrared spectroscopy, known in the literature. The novelty is that the article presents for the first time the experimental far infrared spectra of natural blue and purple halite. It was observed that the blue (178 cm−1) and purple (176 cm−1) halites have the strongest infrared band slightly shifted towards higher wavenumbers compared to colorless halite (174 cm−1). As part of the work, the infrared spectra of the crystal structure models of sodium and potassium chloride were calculated for the first time using the density functional theory (with the B3LYP functional and the 6-31G* basis set, 125-atom model). The proposed approach can be used not only as a powerful method differentiating NaCl and KCl minerals, but it can also help with understanding of different defects in crystal lattices for naturally occurring halides and crystals of other minerals. [ABSTRACT FROM AUTHOR]

The resource utilization of CO 2 is one of the essential avenues to realize the goal of "double carbon". The metal–organic framework (MOF) has shown promising applications in CO 2 catalytic reduction reactions due to its sufficient pore structure, abundant active sites and functionalizability. In this paper, we investigated the electrocatalytic carbon dioxide reduction reactions of single-atom catalysts created by MOF two-dimensional coordination network materials constructed from transition metal-tetrahydroxybenzoquinone using density function theory calculations. The results indicate that for 10 transition metals, TM-THQ single levels ranging from Sc to Zn, the metal atom binding energy to the THQ is large enough to allow the metal atoms to be stably dispersed in the THQ monolayer. The Ni-THQ catalyst does not compete with the HER reaction in an electrocatalytic CO 2 reduction. The primary product of reduction for Sc-THQ is HCOOH, but the major product of Co-THQ is HCHO. The main product of Cu-THQ is CO, while the main product of six catalysts, Ti, V, Cr, Mn, Fe, and Zn, is CH 4 . The limit potential and overpotential of Ti-THQ are the highest, 1.043 V and 1.212 V, respectively. The overpotentials of the other monolayer catalysts ranged from 0.172 to 0.952 V, and they were all relatively low. Therefore, we forecast that the TM-HQ monolayer will show powerful activity in electrocatalytic carbon dioxide reduction, making it a prospective electrocatalyst for carbon dioxide reduction. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of CO2 to valuable fuels and chemicals can not only alleviate the energy crisis but also improve the atmospheric environment. The key is to develop electrocatalysts that are extremely stable, efficient, selective, and reasonably priced. In this study, spin-polarized density function theory (DFT) calculations were used to comprehensively examine the catalytic efficacy of transition metal-hexaaminobenzene (TM-HAB) monolayers as single-atom catalysts for the electroreduction of CO2. In the modified two-dimensional TM-HAB monolayer, our findings demonstrate that the binding of individual metal atoms to HAB can be strong enough for the atoms to be evenly disseminated and immobilized. In light of the conflicting hydrogen evolution processes, TM-HAB effectively inhibits hydrogen evolution. CH4 dominates the reduction byproducts of Sc, Ti, V, Cr, and Cu. HCOOH makes up the majority of Zn's reduction products. Co's primary reduction products are CH3OH and CH4, whereas Mn and Fe's primary reduction products are HCHO, CH3OH, and CH4. Among these, the Ti-HAB reduction products have a 1.14 eV limiting potential and a 1.31 V overpotential. The other monolayers have relatively low overpotentials between 0.01 V and 0.7 V; therefore, we predict that TM-HAB monolayers will exhibit strong catalytic activity in the electrocatalytic reduction of CO2, making them promising electrocatalysts for CO2 reduction. [ABSTRACT FROM AUTHOR]

The catalytic performance of zeolite SSZ-39 with AEI structure is significantly affected by the locations of its extra-framework cation and aluminum distributions. The AEI cage contains three crystallographically inequivalent T sites that tend to be substituted by aluminum. In this work, the Na+ locations and Al distributions in Na-SSZ-39 with different Si/Al ratios were studied by 27Al/23Na MQ MAS NMR spectroscopy together with density functional theory (DFT) calculations. For isolated Al substitution, the T3 site was found to be preferentially occupied by Al, and Na+ was mainly located in the 6-MR (SIIa0) or 8-MR (SIII'a0) sites of the AEI cage, although the priority of SIII'a0 site was slightly higher, and minor Na+ was located inside the hexagonal prism (SIa0). For paired Al substitution, stable AlSiSiAl structure was found to be located in 6-MR, and the corresponding Na+ cations were located at SIIa1 and SIII'a1 sites, respectively. In post-modified zeolites with partial destruction of the framework structure, some free Na+ cations were found to form distinct SIII'b sites. This study deepened the understanding on the structure-reactivity correlation of SSZ-39 zeolite and provided insights into how to fine-tune its catalytic performance.

Abstract Highly efficient electrochemical water splitting is of prime importance in hydrogen energy but is suffered from the slow kinetics at the anodic oxygen evolution reaction. Herein, combining the surface activation with the heterostructure construction strategy, the CoP/Fe‐Co9S8 heterostructures as the pre‐catalyst for highly efficient oxygen evolution are successfully synthesized. The catalyst only needs 156 mV to reach 10 mA cm−2 and keeps stable for more than 150 h. Inductively coupled plasma optical emission spectrometry, in situ Raman spectroscopy and density functional theory calculations verify that the introduction of Fe can promote the formation of highly active Co(IV)–O sites and lead to a self‐termination of surface reconstruction, which eventually creates a highly active and stable oxygen evolution catalytic surface. Besides, the catalyst also demonstrates high hydrogen evolution reaction activity with an overpotential of 62 mV@10 mA cm−2. Benefiting from its bifunctionality and self‐supporting property, the membrane electrode assembly electrolyzer equipped with these catalysts achieves high overall water splitting efficiency of 1.68 V@1 A cm−2.

Nickel oxide is a versatile p‐type semiconducting oxide with many applications in optoelectronic devices, but high doping concentrations are often required to achieve necessary electrical conductivity. In contrast to many other transparent oxide semiconductors, even moderate doping levels in NiO can lead to significant optical absorption in the visible spectral range, limiting the application range of the material. This correlation has been reported extensively in the literature, but its origin has been unknown until now. This work combines experimental data on optical properties from a variety of NiO samples with results from hybrid density functional theory calculations. It shows that strong electron–phonon interaction leads to a significant blueshift (0.6–1 eV) of electronic transitions from the valence band maximum to defect states by light absorption with respect to the thermodynamic charge transition levels. This essentially renders NiO a narrow‐gap semiconductor by defect band formation already at moderate doping levels, with strong light absorption for photon energies of approximately 1 eV. The calculations are also shown to be fully consistent with experimental data on defect‐related light emission in NiO.

Given the abundance of potassium resources, potassium-ion batteries are considered a low-cost alternative to lithium-ion types. However, their electrochemical performance remains rather unsatisfactory because potassium ions have sluggish kinetics and large ionic radius. In this study, NiCo2Se4 nanotube spheres are synthesized as efficient potassium storage hosts via a facile two-step hydrothermal process. The rationally designed electrode has various ameliorating morphological and functional features, including the following: (i) A hollow structure allows for relief of the volume expansion while offering an excellent electrochemical reactivity to accelerate the conversion kinetics; (ii) a high electrical conductivity for enhanced electron transfer; and (iii) myriad vacancies to supply active sites for electrochemical reactions. As such, the electrode delivers an initial reversible capacity of 458.1 mAh g−1 and retains 346.6 mAh g−1 after 300 cycles at 0.03 A g−1. The electrode sustains a high capacity of 101.4 mAh g−1 even at a high current density of 5 A g−1 and outperforms the majority of state-of-the-art anodes in terms of both cyclic capacity and rate capability, especially at above 1.0 A g−1. This study not only proves bimetallic selenides are promising candidates for potassium storage devices but also offers new insight into the rational design of electrode materials for high-rate potassium-ion batteries.

Electrochemical nitrogen reduction reaction (eNRR) is one of the most important chemical reactions for the production of ammonia under ambient environment. However, the lack of in-depth understanding of the structure-activity relationship impedes the development of high-performance catalysts for ammonia production. Herein, the density functional theory (DFT) calculations are performed to reveal the structure-activity relationship for the single-atom catalysts (SACs) supported on g-C3N4, which is modified by molecular groups (i.e., H, O, and OH). The computational results demonstrate that the W-based SACs are beneficial to produce ammonia with a low limiting potential (UL). Particularly, the W-OH@g-C3N4 catalyst exhibits an ultralow UL of −0.22 V for eNRR. And the competitive eNRR selectivity can be identified by the dominant *N2 adsorption free energy than that of *H. Our findings provide a theoretical basis for the synthesis of efficient catalysts to produce ammonia. [ABSTRACT FROM AUTHOR]

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Precise control of alloying sites has long been a challenge, yet little has been achieved in the atomic-level manipulation of metallic nanomaterials. This study reported a three-stage metal and motif exchange mechanism of alloying reaction of an atomically precise ligand-protected [Ag44(p-MBA)30]4− (p-MBA = para-mercaptobenzoic acid) cluster with [Au2(p-NTP)2Cl]− (p-MBA = para-mercaptobenzoic acid). During the first stage (Stage I), an exchange of ligand-shell metal atoms took place. During the second stage (Stage II), the motif exchanged on the [AuAg43(p-MBA)30]4− cluster. During the third stage (Stage III), the Au(I) atom in the ligand-shell was swapped with a Ag(0) atom of the icosahedral Ag12-core. The density functional theory (DFT) calculation results demonstrated that the metal exchange proceeded via different mechanisms at the different reaction stages. In reaction Stages I and II, the metal exchange proceeded via formation of a dianionic [Ag44(p-MBA)30]4−-[Au2(p-NTP)2Cl]− intermediate and then broke and recombined with the ligand-shell. In Stage III, the diffusion of the Au(I) to icosahedral Ag12-core (Stage III) was proceeded via a motif catalyzed heterometal atom diffusion mechanism. We hope that this work will provide a new perspective for the precise control of alloy position in alloyed nanomaterials. [ABSTRACT FROM AUTHOR]

Interfacial energetics for coherent interfaces are typically calculated using two key concepts: interfacial energy and coherency strain energy. Although these calculations are well-established in pristine systems, their direct application to doped systems often leads to inaccuracies. This is primarily because foreign solute atoms not only modify interfacial energetics but also introduce additional mechanical and chemical effects within the bulk phases. To address this, our study employs the PSTRESS tag in VASP to simulate equivalent lattice stresses induced by solute atoms without physically incorporating them. This novel approach allows us to isolate the doping energy caused by the solute atoms' mechanical and chemical effects, thereby enhancing our understanding of the impacts of dopants solely on interfacial energetics. Furthermore, we extend the calculations of interfacial energy and coherency strain energy to doped interfaces, providing a precise and effective evaluation method for both bulk and interfacial energetics in doped systems. [Display omitted] [ABSTRACT FROM AUTHOR]