Synergistic effect of multi-metal site provided by Ni-N, adjacent single metal atom, and Fe nanoparticle to boost CO activation and reduction.

Single transition metal (TM) atom embedded in nitrogen-doped carbon materials with M-N-C configuration have emerged as a promising class of electrocatalysts for electrochemical CO reduction (CORR). However, at high TM atom densities, a comprehensive understanding of the active site structure and reaction mechanisms remains a significant challenge, yet it is crucial for enhancing CORR performance. In this work, we use first-principles calculations to investigate the electrocatalytic performance of Ni-N sites for CO2 reduction to CO, co-assisted by neighboring TM atoms and a Fe nanoparticle.

Rigidly Axial O Coordination-Induced Spin Polarization on Single Ni-N-C Site by MXene Coupling for Boosting Electrochemical CO Reduction to CO.

Regulating the spin states in transition-metal (TM)-based single-atom catalysts (SACs), such as the TM-NC configurations, is crucial for improving the catalytic activity. However, the role of spin in single Ni atoms facilitating the electrochemical CO reduction reaction (CORR) has been largely overlooked. Using first-principles simulations, we investigated the electrocatalytic performance of Ni-N-C SACs vertically stacked on the O-terminated MXene nanosheets for the CORR.

Engineering Spin Polarization of the Surface-Adsorbed Fe Atom by Intercalating a Transition Metal Atom into the MoS Bilayer for Enhanced Nitrogen Reduction.

The precise control of spin states in transition metal (TM)-based single-atom catalysts (SACs) is crucial for advancing the functionality of electrocatalysts, yet it presents significant scientific challenges. Using density functional theory (DFT) calculations, we propose a novel mechanism to precisely modulate the spin state of the surface-adsorbed Fe atom on the MoS bilayer. This is achieved by strategically intercalating a TM atom into the interlayer space of the MoS bilayer.

N-Heterocyclic Olefin Type Ionic Liquid with Innate Soft Lewis-Base Character as an Effective Additive for Hybrid Quasi-2D and 3D Perovskite Solar Cells.

In optimizing perovskites with ionic liquid (IL), the comparative study on Lewis acid-base (LAB) and hydrogen-bonding (HB) interactions between IL and perovskite is lacking. Herein, methyl is substituted for hydrogen on 2-position of imidazolium ring of N-heterocyclic carbene (NHC) type IL IdH to weaken HB interactions, and the resulting N-heterocyclic olefin (NHO) type IL IdMe with softer Lewis base character is studied in both hybrid quasi-2D (Q-2D) and 3D perovskites. It is revealed that IdMe participates in constructing high-quality Q-2D perovskite (n = 4) and provides stronger passivation for 3D perovskite compared with IdH.

Dual-Atom Metal and Nonmetal Site Catalyst on a Single Nickel Atom Supported on a Hybridized BCN Nanosheet for Electrochemical CO Reduction to Methane: Combining High Activity and Selectivity.

Atomically dispersed nitrogen-coordinated transition-metal sites supported on graphene (TM-N-C) offer promising potential for the electrochemical carbon dioxide reduction reaction (CORR). However, a few TM-N-C single-atom catalysts (SAC) are capable of reducing CO to multielectron products with high activity and selectivity. Herein, using density functional theory calculations, we investigated the electrocatalytic performance of a single TM atom embedded into a defective BCN nanosheet for CORR.

Regulating Electronic Spin Moments of Single-Atom Catalyst Sites via Single-Atom Promoter Tuning on S-Vacancy MoS for Efficient Nitrogen Fixation.

The electrocatalytic activity of transition-metal (TM)-based catalysts is correlated with the spin states of metal atoms. However, developing a way to manipulate spin remains a great challenge. Using first-principles calculations, we first report the crucial role of the spin of exposed Mo atoms around an S-vacancy in the electrocatalytic dinitrogen reduction reaction on defective MoS nanosheets and propose a novel strategy for regulating the electronic spin moments by tuning a single-atom promoter (SAP).

Solid solutions of flexible host-guest supramolecules for tuning molecular motion and phase transitions.

By utilizing a supramolecular complex rather than an individual molecule as a deformable and elastic substitutional component, we put forward a solid-solution strategy and demonstrate an example of how two related yet non-isostructural crystalline host-guest compounds can form molecular solid solutions. Interestingly, such a strategy can effectively and continuously modulate the molecular motion and phase transition in them, as revealed by the variable-temperature/frequency dielectric responses.

Synergistic Effect of Boron Nitride and Carbon Domains in Boron Carbide Nitride Nanotube Supported Single-Atom Catalysts for Efficient Nitrogen Fixation.

Developing the low-cost and efficient single-atom catalysts (SACs) for nitrogen reduction reaction (NRR) is of great importance while remains as a great challenge. The catalytic activity, selectivity and durability are all fundamentally related to the elaborate coordination environment of SACs. Using first-principles calculations, we investigated the SACs with single transition metal (TM) atom supported on defective boron carbide nitride nanotubes (BCNTs) as NRR electrocatalysts.

Synergistic Effect of Surface-Terminated Oxygen Vacancy and Single-Atom Catalysts on Defective MXenes for Efficient Nitrogen Fixation.

The production of ammonia (NH) from molecular dinitrogen (N) under ambient conditions is of great significance but remains as a great challenge. Using first-principles calculations, we have investigated the potential of using a transition metal (TM) atom embedded on defective MXene nanosheets (TiCO and TiCO with a Ti vacancy) as a single-atom electrocatalyst (SAC) for the nitrogen reduction reaction (NRR). The TiCO nanosheet with Mo and W embedded, and the TiCO nanosheet with Cr, Mo, and W embedded, can significantly promote the NRR while suppressing the competitive hydrogen evolution reaction, with the low limiting potential of -0.

Metal-Free Boron Nitride Nanoribbon Catalysts for Electrochemical CO Reduction: Combining High Activity and Selectivity.

Developing metal-free catalysts for reduction of CO into energy-rich products is a popular yet very challenging topic. Using density functional theory calculations, we investigated the electrocatalytic performance of C-doped and line-defect (Ld)-embedded boron nitride nanoribbons (BNNRs) for CO reduction reaction (CRR). Because of the presence of bare edge B atoms neighboring to C dopant and C dimer as active sites, defective BNNRs exhibit high CRR catalytic activity and selectivity.

Tuning the activity of the inert MoS surface via graphene oxide support doping towards chemical functionalization and hydrogen evolution: a density functional study.

The basal plane of MoS provides a promising platform for chemical functionalization and the hydrogen evolution reaction (HER); however, its practical utilization remains challenging due to the lack of active sites and its low conductivity. Herein, using first principles simulations, we first proposed a novel and effective strategy for significantly enhancing the activity of the inert MoS surface using a graphene oxide (GO) support (MoS/GOs). The chemical bonding of the functional groups (CH and NH) on the MoS-GO hybrid is stronger than that in freestanding MoS or MoS-graphene.

Regioselective synthesis of 2,3'-biindoles mediated by an NBS-induced homo-coupling of indoles.

Mild conditions have been developed to achieve NBS-induced homodimerization of indole derivatives with excellent regioselectivity at 15 °C in high efficiency. This method provides a simple route to a 2,3'-linked biindolyl scaffold from the electron-rich to moderately electron-poor indoles. In addition, [3,2-a]carbazole derivatives can also be prepared through this method.

Diels-Alder reactions of graphene oxides: greatly enhanced chemical reactivity by oxygen-containing groups.

Graphene oxides (GOs) or reduced GOs (rGOs) may offer extraordinary potential for chemical functionalization of graphene due to their unique electronic and structural properties. By means of dispersion-corrected density functional theory computations, we systematically investigated the Diels-Alder (DA) chemistry of GOs. Our computations showed that the dual nature of GOs as both a diene and a dienophile is stronger than that of pristine graphene.

Oxygen-Molecule Adsorption and Dissociation on BCN Graphene: A First-Principles Study.

Boron and nitrogen co-doped (BCN) graphene is an attractive material for use as a metal-free oxygen reduction reaction electrocatalyst and as other catalysts due to its unique structure and electronic properties. Reported here is the structure, determined by using density functional theory, of the active O -dissociation site of BCN graphene containing different types of BN cluster. The results show that the edge termination and shape of substitutional BN clusters are two important factors that determine the catalytic activity of BCN graphene for the dissociation of molecular oxygen.

Interfacial interaction of Ag nanoparticles with graphene oxide supports for improving NH3 and NO adsorption: a first-principles study.

We investigated the structural and electronic properties of Ag13 nanoparticles (NPs) deposited on graphene oxides (GOs) and the effect of the interfacial interaction on NH3 and NO adsorption using density functional theory calculations. The epoxy functional group and its neighboring sp(2) carbon atoms of GOs, rather than the hydroxyl group, are used as active sites to enhance the binding of Ag13 to graphene through the C-O-Ag and C-Ag chemical bonds. The stability of deposited Ag NPs depends on the chemical environment of active sites in GOs, including the atomic arrangement of epoxides and their concentration.

Realizing semiconductor-half-metal transition in zigzag graphene nanoribbons supported on hybrid fluorographene-graphane nanoribbons.

Hydrogenation and fluorination provide promising applications for tuning the properties of graphene-based nanomaterials. Using first-principles calculations, we investigate the electronic and magnetic properties of zigzag graphene nanoribbons (ZGNRs) supported on hydrogenated and fluorinated ZGNRs. Our results indicate that the support of zigzag graphane nanoribbon with its full width has less impact on the electronic and magnetic properties of ZGNRs, whereas the ZGNRs supported on fluorographene nanoribbons can be tuned to metal with almost degenerated ferro- and anti-ferromagnetic states due to the intrinsic polarization of substrate.

Cu(II)-catalyzed highly regio- and stereoselective construction of C-C double bonds: an efficient method for the ketonization-olefination of indoles.

A general and efficient method for the cross-coupling of indoles with β-keto esters by using TEMPO/CuSO4·5H2O in air as oxidant has been developed. This reaction features high functional-group compatibility and an excellent selectivity. This methodology provides an alternative approach for the ketonization-olefination of indoles in moderate to good yields.

Tunable doping and band gap of graphene on functionalized hexagonal boron nitride with hydrogen and fluorine.

First-principles calculations have been used to investigate the structural and electronic properties of graphene supported on functionalized hexagonal boron nitride (h-BN) with hydrogen and fluorine atoms. Our results show that the hydrogenation and fluorination of the h-BN substrate modify the electronic properties of graphene. Interactions of graphene with fully hydrogenated or fully fluorinated h-BN and half-hydrogenated and half-fluorinated h-BN with H at N sites and F at the B sites can lead to n- or p-type doping of graphene.

Site-dependent catalytic activity of graphene oxides towards oxidative dehydrogenation of propane.

Graphene oxides (GOs) may offer extraordinary potential in the design of novel catalytic systems due to the presence of various oxygen functional groups and their unique electronic and structural properties. Using first-principles calculations, we explore the plausible mechanisms for the oxidative dehydrogenation (ODH) of propane to propene by GOs and the diffusion of the surface oxygen-containing groups under an external electric field. The present results show that GOs with modified oxygen-containing groups may afford high catalytic activity for the ODH of propane to propene.

Adsorption of nitrogen oxides on graphene and graphene oxides: insights from density functional calculations.

The interactions of nitrogen oxides NO(x) (x = 1,2,3) and N(2)O(4) with graphene and graphene oxides (GOs) were studied by the density functional theory. Optimized geometries, binding energies, and electronic structures of the gas molecule-adsorbed graphene and GO were determined on the basis of first-principles calculations. The adsorption of nitrogen oxides on GO is generally stronger than that on graphene due to the presence of the active defect sites, such as the hydroxyl and carbonyl functional groups and the carbon atom near these groups.

Carbon-doped zigzag boron nitride nanoribbons with widely tunable electronic and magnetic properties: insight from density functional calculations.

First-principles calculations within the local spin-density approximation have been used to investigate the electronic and magnetic properties of carbon chain-doped zigzag born nitride nanoribbons (ZBNNRs). Our results indicate that doped half-bare ZBNNRs with an H-passivated B edge and a bare C edge generally have a spin-polarized ground state with the ferromagnetic spin ordering localized at the C edge, independent of the doping concentration and the ribbon width. In particular, doped half-bare ZBNNRs for all widths may produce half-semiconducting --> half-metallic --> metallic behavior transitions without an external electric field as the doping proceeds gradually from the N edge to the B edge.

Defect-induced chemisorption of nitrogen oxides on (10,0) single-walled carbon nanotubes: Insights from density functional calculations.

The interactions of NO(x) (x=1,2,3) with the defective semiconducting (10,0) carbon nanotubes were studied by the density functional theory. Optimized geometries, binding energies, and electronic structures of the NO(x)-adsorbed nanotubes were determined on the basis of calculations. Effects of the defect density and the electric field on the binding energy and charge transfer have been investigated.

Density functional characterization of adsorption and decomposition of 1-propanethiol on the Ga-rich GaAs (001) surface.

Density functional calculations have been used to investigate adsorption and decomposition of 1-propanethiol on the Ga-rich GaAs (001) surface. The dissociative adsorption of 1-propanethiol on GaAs (001) to the chemisorbed propanethiolate and hydrogen was predicted to be quite facile. Followed by the C-S bond scission of the propanethiolate species, the surface propyl species was formed with a barrier of 47.