Search

Magnetic property (e.g. spin order) of support is of great importance in the rational design of heterogeneous catalysts. Herein, we have taken the Ni-supported ferromagnetic (FM) CrBr3 support (Nix/CrBr3) to thoroughly investigate the effect of spin-order on electrocatalytic oxygen reduction reaction (ORR) via spin-polarized density functional theory calculations. Specifically, Ni loading induces anti-FM coupling in Ni–Cr, leading to a transition from FM-to-ferrimagnetic (FIM) properties, while Ni–Ni metallic bonds create a robust FM direct exchange, benefiting the improvement of the phase transition temperature. Interestingly, with the increase in Ni loading, the easy magnetic axis changes from out-of-plane (2D-Heisenberg) to in-plane (2D-XY). The adsorption properties of Nix/CrBr3, involving O2 adsorption energy and configuration, are not governed by the d-band center but strongly correlate with magnetic anisotropy. It is noteworthy that the applied potential and electrolyte acidity triggers spin-order transition phenomena during the ORR and induces the catalytic pathway change from 4e− ORR to 2e− ORR with the excellent onset potential of 0.93 V/reversible hydrogen electrode, comparable to the existing most excellent noble-metal catalysts. Generally, these findings offer new avenues to understand and design heterogeneous catalysts with magnetic support. [ABSTRACT FROM AUTHOR]

Tailoring the specific properties to practical applications by structural modification is of vital importance for the envisioned development of two-dimensional ferroelectric materials. Herein, a comprehensive investigation on the effects of single doping on the ferroelectric properties and electronic transport in a monolayer of α-In2Se3 was carried out via the combination of first-principles density functional theory calculations and electron–phonon coupling simulations. Our results show that single-doping in In2Se3 can reduce effective mass of carriers and thereby enhance the high carrier mobility potential of the material. Moreover, the ferroelectric phonon mode in single-doped In2Se2X features a lower scattering rate, associating with the single-doping atom, and indicates reduced hindrance to carrier transport during ferroelectric switching. Compared to pristine In2Se3, the obtained smaller ferroelectric barriers (<1 eV) of single-doped ones promote more promising ferroelectricity from the analysis of the ferroelectric soft mode. Interestingly, the observed variations in ferroelectric behaviors resulting from doping of different elements highlight the significance of single-doping in modifying the ferroelectric properties of monolayers. Furthermore, strain engineering results reveal that single doping obviously affects the dependence of gap on strains: linear relationship for doping ones and nonlinearity for pristine one. Our study provides valuable insights into achieving higher carrier mobility in these critical materials. [ABSTRACT FROM AUTHOR]

Investigating spin dynamics in electrocatalysis is crucial for the rational design of magnetically heterogeneous catalysts. Utilizing spin‐polarized density functional theory calculation, herein, the spin dynamic of diatomic Co₂‐supported γ‐graphyne (Co2‐GY) catalysts during the process of CO electroreduction (eCORR) is identified, focusing on the effect of the applied potential and acidity on spin dynamic and catalytic performance. In particular, the obtained Co2‐GY shows a new efficient C2 pathway of CH2* + CHO* coupling mechanism, resulting in the optimal CH3CH2OH product with ∆G of 0.50 eV and the selectivity of 99.99% under alkaline conditions. Under acidic media, Co2‐GY exhibits the optimal C1 product (CH3OH) with ∆G of 0.27 eV and a selectivity of 99.99%. During CO electroreduction, the reaction environment (pH and applied potential) influences spin dynamics in catalyst‐reactant systems, affecting the spin transition of diatomic Co2 active sites among four magnetic states: ferromagnetic, antiferromagnetic, paramagnetic, and diamagnetic. These findings will be helpful for the rational design of transition‐metal heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The search of excellent electrocatalysts for the two-electron O2-reduction reaction (2e− ORR) is of great importance for the green synthesis of H2O2. This study developed a computational framework using density functional theory (DFT) and ab initio molecular dynamic simulation (AIMD) to investigate the influence of acid electrolytes, particularly H coverage, on the s-band center of a single-atomic Ag catalyst, leading to improved catalytic selectivity for the ORR. Specially, the screened catalyst Ag@Ti2C exhibited remarkable intrinsic performance for 2e− ORR with an overpotential of only 0.06 V. In acidic electrolytes, Ag@Ti2C selectively bound to O-containing and H species, forming Ag@Ti2CO2Hx. The introduction of O functional groups improved the electron delocalization, enhancing O2–Ag interactions. Significantly, the surface O atom's p-band center exhibited a parabolic trend with the H coverage on Ag@Ti2CO2. Consequently, the catalyst exhibited an optimal overpotential of 0.08 V for 2e− ORR at an H atom coverage of 22.2%. It was found that the surface O p-state played a crucial role in mediating the s-band center of the single-atomic Ag catalyst, significantly influencing its catalytic performance in the ORR. [ABSTRACT FROM AUTHOR]

An excellent single-atomic photocatalyst, Ti@C4N3, is theoretically found to effectively convert CO2 to C2H6 by density functional theory (DFT) calculations and non-adiabatic molecular dynamics (NAMD) simulations. The Ti@C4N3 photocatalyst has remarkable stability both thermally, chemically, and mechanically. Electronically, it has strong absorption properties (λ = 327.77 and 529.61 nm), suitable band positions, and a long photogenerated electron lifetime (τe = 38.21 ps), allowing photogenerated electrons to migrate to the surface. Notably, the high-valence active site effectively activates two CO2 through dual activation: Under light irradiation, the weakly adsorbed CO2 undergoes photo-induced activation by the photoelectron of conduction band minimum (CBM); without light, the high Lewis acidity of the Ti site induces CO2 activation through back-donating π-bond. Contrast simulation results uncovered that dual activation of CO2 is attributed to the thermal and photonic synergy. Furthermore, two activated CO2 species under light easily couple to form oxalate with the barrier of 0.19 eV, and further reduced to C2H6 with a low activation energy of 1.09 eV. [ABSTRACT FROM AUTHOR]

The rational design of high-performance catalysts for oxygen reduction reactions (ORRs) is of great importance for large-scale applications in the field of proton-exchange membrane fuel cells and the green synthesis of H2O2. The effect of spin states of paramagnetic metal ions on the selectivity of ORRs is significant for single-atom catalysts (SACs). In this work, via spin-polarization density functional theory (DFT) calculations, we systematically investigated the popular paramagnetic metal–nitrogen graphene (M–N4–C, M = Mn, Fe, and Co) SACs to mainly focus on the correlation of spin states and catalytic performance (e.g. activity and selectivity). Both thermodynamically and kinetically, it was found that Co–N4–C (S = 1/2) has excellent 2e− oxygen reduction performance (hydrogen peroxide production) with an ultralow overpotential of 0.03 V, and the hydrogenation of OOH* is the rate-determining step (RDS) with an energy barrier of 1.20 eV. The 4e− ORR tends to occur along the OOH dissociation pathway (O* + OH*) on Co–N4–C (S = 3/2), in which OOH* decomposition is the RDS with an energy barrier of 1.01 eV. It is proved that the spin magnetic moment is the key factor to regulate the ORR property via multi-angle electronic analysis. The spin states of catalysts play a crucial role in the activity and selectivity of ORRs mainly by manipulating the bond strength between OOH and catalysts. This will provide new insights for the rational design of ORR catalysts with magnetic metals. [ABSTRACT FROM AUTHOR]

Abstract: The largest known polyoxometalate (POM)‐templated silver‐alkynyl cluster, [(EuW10O36)2@Ag72(tBuC≡C)48Cl2⋅4 BF4] (SD/Ag20), was isolated under solvothermal conditions and structurally characterized. It was confirmed by single‐crystal X‐ray diffraction (SCXRD) as a {EuW10}2‐in‐{Ag72} clusters‐in‐cluster rod‐like compound. The high‐resolution electrospray ionization mass spectrometry (HR‐ESI‐MS) shows that such a double anion‐templated cluster is assembled from a crucial single anion‐templated Ag42 intermediate in the solution. The crystallization of Ag42 species (SD/Ag21), followed by SCXRD, gave an important clue about the assembly route of SD/Ag20 in solution: the Ag42 cluster eliminates six silver atoms laterally, then fuses together at the vacant face to form the final Ag72 cluster (elimination‐fusion mechanism). The characteristic emission of [EuW10O36]9− is well maintained in SD/Ag20. This work not only provides a new method for the synthesis of larger silver clusters as well as the functional integration of the silver cluster and POMs, but also gives deep insights about the high‐nuclear silver cluster assembly mechanism. [ABSTRACT FROM AUTHOR]