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This theoretical study explores the reduction of CO2 to CH4 on Co4@Se-doped carbon nitride, while HCOOH/CO forms without cobalt, agreeing with the experiments.

Functional group-modified carbon nitride nanoribbons can effectively improve the photocatalytic performance and reduce the Gibbs free energy of CO2 reduction.

Combination of defect structure and tensile strain is an effective approach to enhance the hydrogen evolution reaction activity of hybrid MoS2/graphene.

DFT calculations were used to study the performance of Na2ZrO3 and Y-doped Na2ZrO3 as cathode materials for sodium ion batteries, including the stability of desodiated structures, desodiation energy, redox mechanism, and diffusion of Na ion.

Two single-phase MOCPs with different electron and proton conductivities were used for the electrocatalytic CO2RR.

With the advantage of excellent light absorption ability and earth-abundant elements, Cu2ZnSnS4 (CZTS) is widely applied in the photoelectrochemical (PEC) reduction of CO2. However, the microscopic...

The adsorption behaviors of CO2 at the Cu n /TiC(001) interfaces (n = 1-8) have been investigated using the density functional theory method. Our results reveal that the introduction of copper clusters on a TiC surface can significantly improve the thermodynamic stability of CO2 chemisorption. However, the most stable adsorption site is sensitive to the size and morphology of Cu n particles. The interfacial configuration is the most stable structure for copper clusters with small (n ≤ 2) and large (n ≥ 8) sizes, in which both Cu particles and TiC support are involved in CO2 activation. In such a case, the synergistic behavior is associated with the ligand effect introduced by directly forming adsorption bonds with CO2. For those Cu n clusters with a medium size (n = 3-7), the configuration where CO2 adsorbs solely on the exposed hollow site constructed by Cu atoms at the interface shows the best stability, and the charger transfer becomes the primary origin of the synergistic effect in promoting CO2 activation. Since the most obvious deformation of CO2 is observed for the TiC(001)-surface-supported Cu4 and Cu7 particles, copper clusters with specific sizes of n = 4 and 7 exhibit the best ability for CO2 activation. Furthermore, the kinetic barriers for CO2 dissociation on Cu4- and Cu7-supported TiC surfaces are determined. The findings obtained in this work provide useful insights into optimizing the Cu/TiC interface with high catalytic activation of CO2 by precisely controlling the size and dispersion of copper particles.

Weak carbon adsorption on Ni–Mox and easy carbon elimination on MoOx@Ni leads to high coke resistance of the Ni/Mo catalyst.

Charge generation and separation are regarded as the major constraints limiting the photocatalytic activity of polymeric photocatalysts. Herein, two new linear polyarylether-based polymers (PAE-CPs) with distinct linking patterns between their donor and acceptor motifs were tailor-made to investigate the influence of different linking patterns on the charge generation and separation process. Theoretical and experimental results revealed that compared to the traditional single-stranded linker, the double-stranded linking pattern strengthens donor-acceptor interactions in PAE-CPs and generates a coplanar structure, facilitating charge generation and separation, and enabling red-shifted light absorption. With these prominent advantages, the PAE-CP interlinked with a double-stranded linker exhibits markedly enhanced photocatalytic activity compared to that of its single-strand-linked analogue. Such findings can facilitate the rational design and modification of organic semiconductors for charge-induced reactions.

The adsorptions of iron(II) phthalocyanine (FePc) on graphene and defective graphene were investigated systematically using density functional theory. Three types of graphene defects covering stone-wales (SW), single vacancy (SV), and double vacancy (DV) were taken into account, in which DV defects included DV(5-8-5), DV(555-777), and DV(5555-6-7777). The calculations of formation energies of defects showed that the SW defect has the lowest formation energy, and it was easier for DV defects to form compared with the SV defect. It is more difficult to rotate or move FePc on the surface of defective graphenes than on the surface of graphene due to bigger energy differences at different sites. Although the charge analysis indicated the charge transfers from graphene or defective graphene to FePc for all studied systems, the electron distributions of FePc on various defective graphenes were different. Especially for FePc@SV, the d

The natural abundance of potassium in the earth’s crust is 1000 times higher than that of lithium, so energy technologies built on potassium are more sustainable. Potassium-ion batteries have attra...

First-principles computations were performed to investigate the performance of KTiOPO4 (KTP) as a cathode material for potassium-ion batteries (PIBs), including the stability and electronic properties of depotassiated structures and mechanisms of K deintercalation and diffusion. As depotassiation proceeds, oxygen hole polarons are produced, and there are not peroxides or superoxides formed after deep depotassiation. The anionic oxygen redox in KTP provides a voltage vs K/K+ over 4 V by the PBE+U method and over 5 V with the more reliable HSE06 hybrid functional. When all K in KTP is removed, the calculated volume compression is only 1.528%. The AIMD simulations at 300 K for TiOPO4 verify its thermal stability. The PBE+U calculations predict a low ion diffusion barrier of 0.29 eV in bulk KTP, indicating a good charge-discharge rate for KTP as a cathode for PIBs. All of the calculated results indicate that KTP can be a promising cathode material for PIBs.

Defect engineering can modify the physical and chemical properties of two-dimensional (2D) materials to advance their effectiveness for applications. Here, we have designed three kinds of single ca...

Lithiated transition metal oxide cathode materials that combine oxygen-anion redox [O2–/(O2)n−] with cation redox offer substantial capacities and higher voltage than cathodes without oxygen redox,...

Photocatalytic H2 production via water splitting holds great potential for the conversion of solar energy into renewable and storable chemical fuels in a sustainable manner, but this up-hill reaction is mainly hindered by the water oxidation process. This reaction is sluggish and relies on high overpotentials (wasted energy), while only oxygen is generated as a low value oxidation by-product. Coupling hydrogen generation to a less unfavorable oxidation reaction creating higher value products is therefore a recommendable issue. Here we found that poly(heptazine imide) (PHI), a stable and reactive allotrope of crystalline carbon nitride, supported with highly dispersed Pt nanoparticles (PtNPs) could achieve efficient and persistent H2 and CH4 production by photocatalytic reforming of biomass derived alcohols under visible light irradiation. The results reveal that PHI with low grain boundary defects restrains the bulk charge carrier recombination and largely promotes photocatalytic efficiency. The apparent quantum efficiency (AQE) of the optimized material for visible light H2 evolution could reach values as high as 15% at 420 nm. The DFT results reveal that the activity is associated with the Tafel step rather than the Volmer–Tafel step. This study highlights the development of a new covalent scaffold for the simultaneous generation of storable and valuable chemical fuels (H2 and CH4) in a feasible photocatalytic manner.

Ni-rich layered oxides, like LiNi0.8Co0.1Mn0.1O2 (NCM811), have been widely investigated as cathodes due to their high energy density. However, gradual structural transformation during cycling can lead to capacity degradation and potential decay of cathode materials. Herein, we doped high-valence transition metal (TM) ions (V5+, Nb5+, and Zr4+) at the Ni site of NCM811 by first principles simulations and explored the mechanism of doping TMs in NCMs for enhancing the electrochemical performance. Analysis of the calculations shows that doping V, Nb and Zr has an efficient influence on alleviating the Ni oxidation, reducing the loss of oxygen, and facilitating Li+ migration. Moreover, V doping can further suppress the lattice distortion due to the radius of V5+ being close to the radius of Mn4+. In particular, compared with the barrier of the pristine NCM in Li divacancy, the barrier of V-doped NCM reaches the lowest. In conclusion, V is the most favorable dopant for NCM811 to improve the electrochemical properties and achieve both high capacity and cycling stability.

CH3NH3PbBr3@CsPbBr3 quantum dots were prepared by epitaxially growing a CsPbBr3 shell on the surface of CH3NH3PbBr3 due to their similar crystal structures. The inorganic CsPbBr3 shell provides enhanced stability for the CH3NH3PbBr3 core. Compared with that of CH3NH3PbBr3, the photoluminescence of CH3NH3PbBr3@CsPbBr3 quantum dots is not only strong, but also stable for months, in addition to having a high quantum yield.

A new (La,Sr)(Al,Ta)O3 (LSAT) crystal is focused on in this paper to be used as an ideal substrate for preparing perfect BiFeO3 thin films. The crystal structures are designed with a low lattice mismatch between LSAT and BiFeO3. LSAT crystals were grown by the Czochralski method. In order to get colourless crystals with high transmittance, density functional theory is used to simulate the crystals with different defects. From the results, it is found that the colour centre originates from the defect of VSr + VO or VSr + 2VO. Thus, it is necessary for the crystals to be annealed in O2 and then in N2. High-quality BiFeO3/LSAT thin films will have promising application prospects.

Because of the high efficiency and mild reaction conditions, electrocatalytic CO2 reduction (ECR) has attracted significant attention in recent years. However, the specific mechanism of the formation of the two-electron production (CO or HCOOH) in this reaction is still unclear. Herein, with density functional theory calculation and experimental manipulation, the specific mechanism of the selective two-electron reduction of CO2 has been systematically investigated, employing the polyphenolate-substituted metalloporphyrinic frameworks, ZrPP-1-M (M = Fe, Co, Ni, Cu, and Zn), as model catalysts. Experimental observations and theoretical calculations discovered that ZrPP-1-Co is a more favorable catalyst for ECR among them. Compared with the formation of HCOOH, electroreduction of CO2 into CO has more beneficial thermodynamic and kinetic routes with ZrPP-1-Co as a catalyst. After introducing the r-GO for improving the conductivity, the Faradaic efficiency for CO formation is 82.4% at -0.6 v (vs RHE).

A facile procedure for doping copper species into CeO2 lattices to prevent ceria from being deactivated and to offer additional active sites for selective H2S oxidation is reported here. Among the prepared catalysts, porous 10Cu/Ce nanorods with well-defined (100) and (110) reactive planes display excellent catalytic performance, exhibiting H2S conversion and sulfur selectivity of 100% at 220 °C, which is higher than those of most reported Ce-based catalysts. More importantly, electron transfer from Cu+ to Ce4+ suppresses the transfer of electrons from SO2 to Ce4+, leading to inhibition of SO2 oxidation to surface sulfate , which could deactivate the catalyst. Overall, the results of systematic experimental and theoretical studies prove that copper doping effectively promotes the formation of oxygen vacancies and resistance against SO2 poisoning. Furthermore, through in situ diffuse reflection infrared Fourier transform spectroscopy investigation and density functional theory calculations, the reaction intermediates in selective H2S oxidation and mechanism of SO2 resistance over the Cu-doped CeO2 catalysts are revealed.

The industrial synthesis of NH3 using Fe- or Ru-based catalysts usually requires harsh reaction conditions. It is desirable to develop catalysts that perform well at low temperature and pressure (2...

H2S is abundantly available in nature, and it is a common byproduct in industries. Molybdenum sulfides have been proved to be active in the catalytic decomposition of hydrogen sulfide (H2S) to prod...

Electrocatalytic nitrogen fixation using single-atom catalysts（SAC）offers a promising strategy for the sustainable production of NH3. Based on the density functional theory, we systematically explo...

Three classical Fe-MOFs, viz., MIL-100(Fe), MIL-101(Fe), and MIL-53(Fe), were synthesized to serve as platforms for the investigation of structure–activity relationship and catalytic mechanism in t...

Silicon carbide and its nanocomposites have recently emerged as a promising candidate for anodes in lithium-ion batteries. We systematically investigate the geometric structures and electronic stru...

CeO2-based catalysts are potentially suitable for H2S-selective oxidation, but their practical application is limited due to the problem of sulfate formation. Herein, we report a facile citric acid...

The adsorption, activation and reduction of CO2 over Fex/Cu(100) (x = 1–9) surfaces were examined by density functional theory. The most stable structure of CO2 adsorption on the Fex/Cu(100) surface was realized. The electronic structure analysis showed that the doped Fe improved the adsorption, activation and reduction of CO2 on the pure Cu(100) surface. From the perspective of thermodynamics and kinetics, the Fe4/Cu(100) surface acted as a potential catalyst to decompose CO2 into CO with a barrier of 32.8 kJ mol−1. Meanwhile, the first principle molecular dynamics (FPMD) analysis indicated that the decomposition of the C–O1 bond of CO2 on the Fe4/Cu(100) surface was only observed from 350 K to 450 K under a CO2 partial pressure from 0 atm to 10 atm. Furthermore, the results of FPMD analysis revealed that CO2 would rather decompose than hydrogenate when CO2 and H co-adsorbed on the Fe4/Cu(100) surface.

This paper focuses on strong magneto-optical thin films that closely match a Si substrate. The orthorhombic perovskite crystal structure of CeFeO3 was optimized to a cubic perovskite structure by introducing strontium and vanadium ions into lattice. The cubic Ce1-xSrxFe1-xVxO3 (x = 0.3, 0.5, 0.7) thin films with high quality and high growth orientation were prepared on a Si substrate by using the RF magnetron sputtering method. Moreover, the birefringence effect, which may weaken the magneto-optical effect, should not occur in the cubic thin film. The calculation results based on density functional theory show that the increased electronic transition probability is attributed to the strong spin-coupling between the hybrid Ce3+ 4f and Fe3+/V4+ 3d states. The magnetic circular dichroism ellipticity |ΨF| of the Ce0.7Sr0.3Fe0.7V0.3O3 thin film is up to 4300 deg. cm-1, which indicates a strong magneto-optical effect. Therefore, the cubic Ce1-xSrxFe1-xVxO3/Si film with high Ce3+ concentration is expected to be a new candidate for integrated magneto-optical devices.

An in-depth understanding of the microscopic reaction mechanism on a nonmetal-doped catalytic system at the atomic level is one of the critical approaches to developing new efficient catalysts. Herein, the effects of S-doping on melon-based carbon nitride (CN) for the photocatalytic selective oxygen reduction reaction (ORR) have been comprehensively investigated by first-principles calculations. The configurations, electronic properties, optical properties, and the reaction performance of the S-doped melon-based CN have been studied and discussed. The results demonstrate that the decoration with S atoms exhibited substantial effects, involving the redistribution of the charge density and tuning of the bandgap, which promote the photocatalytic selective ORR activity. Accordingly, O2 is activated on the S-doped system with about 0.4 e of charge obtained from catalytic surfaces, leading to the thermodynamically feasible H2O2 and H2O formation, which is in good agreement with the experimental results. Our results provide theoretical insights into the design and development of polymeric carbon nitride (PCN) as well as other metal-free photocatalysts for the selective ORR.

On the basis of the electron “acceptance-donation” concept, a boron decorated melon-based carbon nitride (CN) is studied as a metal-free photocatalyst to efficiently reduce N2 to NH3 under visible light irradiation. The results revealed that a boron-interstitial (Bint)-decorated melon-based CN has an outstanding N2 reduction capacity through the enzymatic mechanism with a rather low overpotential (0.32 V). The excellent efficiency and selectivity of Bint-decorated melon-based CN in N2 reduction reaction (NRR) are attributed to the concentrated spin polarization on the B atom, the significant enhancement of visible and infrared light absorption, and the effective inhibition of the competitive hydrogen evolution reaction (HER). Importantly, B-doped melon-based CN has been successfully synthesized in the experiments, so obtaining Bint-decorated melon is promising, while proton transfer from the –NH2 group in CN to the B atom surely will affect the functionality of the catalyst through deactivation of the N2 adsorption site. Our study provides a novel single atom metal-free photocatalyst with high efficiency for NRR, which is conducive to the sustainable synthesis of ammonia.