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[Display omitted] • Transition metal loading (TM+Ni − MgO) and doping (Ni − TM/MgO) were constructed and used for DRM. • The adsorption of CO 2 and CH 4 on these structures was analyzed. • DRM reactions on Fe and Ni loaded MgO (FeNi − MgO) and Ni − loaded, Fe − doped MgO (Ni − Fe/MgO) were screened. • The addition of Fe lowered the energy barrier for some of the elementary reaction steps. • Ni − Fe/MgO showed greater advantages due to the smallest CO 2 dissociation energy barrier. In the context of carbon peaking and carbon neutrality goals, dry reforming of methane (DRM) offers both environmental and economic benefits and holds great promise for development. In this work, based on Ni loaded MgO, two structural models constructed by transition metal loading (TM+Ni − MgO, TM=Fe, Zr, Mo) and doping (Ni − TM/MgO) were used for DRM by density functional theory (DFT). And the adsorption of CO 2 and CH 4 on these structures was analyzed. The partial density of states (PDOS) and charge density difference (CDD) indicate that due to the presence of unfilled electron d − orbitals in the TM atoms, electron transfer occurs between them and the p − orbitals of the C and O atoms. It facilitates the interactions and enhances the adsorption between CO 2 and MgO. On this basis, the DRM reactions on Fe and Ni loaded MgO (FeNi − MgO) and Ni − loaded, Fe − doped MgO (Ni − Fe/MgO) were screened for focused research. It was revealed that the addition of Fe lowered the energy barrier values for some of the elementary reaction steps, allowing the reaction to proceed more easily. And Ni − Fe/MgO showed greater advantages by possessing more stable energy barrier fluctuation intervals (ER1 − ER3) and the smallest CO 2 dissociation energy barrier. [ABSTRACT FROM AUTHOR]

The chemico-physical properties including structural, electronic, vibrational and thermodynamic properties of α-quartz Si 1 -x Ce x O 2 and stishovite Si 1 -x Ce x O 2 (x varies from 0.0 to 0.5) have been researched by the density functional theory (DFT). For α-quartz Si 1 -x Ce x O 2 , when Ce content x gently augments from 0.0 to 0.5, the lattice constants a and c increase from 4.999 Å to 6.722 Å and from 5.494 Å to 7.360 Å respectively. With regard to stishovite Si 1 -x Ce x O 2 , the constants a and c increase from 4.234 Å to 5.235 Å and from 2.688 Å to 3.532 Å, respectively. The calculated band gap decreases first and then increases for both two structures. For α -quartz and stishovite Si 1 -x Ce x O 2 , the calculated results of vibrational characters indicate that the increasing of Ce concentration from 0.0 to 0.5 leads to the peak vibrational frequency reducing from about 35.947 THz down to about 26.702 THz and from 30.494 THz down to about 21.981 THz, respectively. This metamorphic variation shows that these modes have a lower dispersive rate of change and phonon group velocities. Finally, the thermodynamic properties associated with phonons have been achieved and explored. • As Ce content x augments from 0.0 to 0.5, the lattice constant increases for Si 1 -x Ce x O 2. • As the increasing of Ce content from 0.0 to 0.5, the band gap first decreases and then increases. • The increase of Ce content leads to the decreasing of phonon vibration frequency. • The increase of Ce concentration leads to F and E decrease, while S and C V augment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-atom cadmium sulfide (TM − CdS) doped with 13 transition metals (TM) were constructed by DFT. • The structural stability and mechanism of ammonia synthesis were calculated. • Based on stability, number of transferred electrons, and NRR activity, Fe − CdS, Mo − CdS, and Ru − CdS are more advantageous than others. • The limiting potential for the occurrence of NRR on the Mo − CdS structure is − 0.261 V, which is the lowest. • Detailed reaction path and energy barrier of NRR by 13 transition metal doped CdS were discussed. Single-atom catalysts with ultra-high atomic utilization and selectivity show great potential in the production of NH 3 through electrocatalytic nitrogen reduction reaction (NRR). In this paper, 13 single-atom cadmium sulfide (TM − CdS) doped with different transition metals (TM) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Ag) were constructed separately using a density functional theory approach to calculate the structural stability and the reaction mechanism of catalytic ammonia synthesis. hree systems, Fe − CdS, Mo − CdS, and Ru − CdS, were screened out from the 13 doped metal 0structures on the basis of the computational results. The above three systems have more stable structures, can transfer more charge to activate N 2 molecules, and exhibit better NRR catalytic activity. The limiting potential NRR on the Mo − CdS structure is only − 0.261 V, which is lower than that of Fe − CdS (−0.353 V), Ru − CdS (−0.461 V) and CdS (−2.124 V). This work will be of great value of designing and employing the doped single-atom catalysts for efficient electrolytic nitrogen reduction reaction. [ABSTRACT FROM AUTHOR]

• Ni loaded BN (Ni/BN) and transition metal doped Ni loaded BN (TM Ni/BN) were constructed. • 29 kinds of TM were screened for the effects on DRM catalytic performance and mechanism. • TM atoms have electron-unfilled d orbitals, which can promote the interaction between CO 2 and TM Ni/BN. • TM Ni/BN (TM = V, Mo, Ru) were screened to further catalyzing the whole DRM reactions. • Carbon deposition mechanism was further studied, and V Ni/BN performed the best. In the context of carbon peaking and carbon neutrality goals, dry reforming of methane (DRM) is attracting attention for its ability to convert greenhouse gases into synthesis gas with economic and environmental benefits. However, the commercialization of DRM has been limited by catalyst sintering and carbon deposition. In this work, Ni loaded BN (Ni/BN) and transition metal doped Ni loaded BN (TM Ni/BN) structures were constructed by density functional theory (DFT) in this work. 29 kinds of TM were screened for the effects on DRM catalytic performance and mechanism. It shows that TM have electron-unfilled d orbitals, which can promote the interaction between CO 2 and TM Ni/BN. After stability analysis of TM Ni/BN and adsorption calculation of CO 2 and CH 4 , three structures of TM Ni/BN (TM = V, Mo, Ru) were screened to further catalyze the DRM reaction. The carbon deposition problem was analyzed from the reaction mechanistic point of view. And it was further determined that the V Ni/BN structure performed the best. In summary, Ni and TM bimetallic catalysts were designed, and TM was screened comprehensively to provide some theoretical references for exploring the DRM reaction mechanism and realizing the goal of reducing carbon and increasing the source. [Display omitted] [ABSTRACT FROM AUTHOR]

The problems of poor Faraday efficiency and high overpotential usually limit electrochemical nitrogen reduction (NRR) catalysts. In this paper, 28 different transition metal single-atoms (TM-SAs) supported on W 2 N 3 (TM@W 2 N 3) were designed by density functional theory (DFT) for catalytic N 2 reduction. The stability, N 2 activation capacity, selectivity and NRR mechanism of TM@W 2 N 3 were analyzed. Following the screening process, only 9 TM@W 2 N 3 (TM=Sc, Ti, V, Co, Cu, Y, Mo, Ag, W) structures were identified as exhibiting high stability, strong activation capacity and high NRR selectivity. And then N 2 activation mechanism of V@W 2 N 3 , Mo@W 2 N 3 and W@W 2 N 3 , as well as the Gibbs free energies of its four NRR reaction pathways were further discussed. The overpotentials (η) of Mo@W 2 N 3 and V@W 2 N 3 to NRR are 0.129 V and 0.470 V, respectively. The overpotential (η) of W@W 2 N 3 is the lowest at 0.059 V, while its catalytic activity is the highest. V@W 2 N 3 and W@W 2 N 3 are more likely to follow the distal pathway for NRR, while Mo@W 2 N 3 is more likely to follow the enzymatic pathway. This study offers some theoretical foundation and reference for the design of new and efficient electrocatalytic NRR catalysts. [Display omitted] • 28 transition metal supported on W 2 N 3 (TM@W 2 N 3) were designed by DFT for NRR. • Analyzed TM@W 2 N 3 : stability, N 2 activation capacity, selectivity and NRR mechanism. • N 2 activation mechanism of V@W 2 N 3 , Mo@W 2 N 3 and W@W 2 N 3 for NRR pathways were discussed. • V@W 2 N 3 and W@W 2 N 3 follow the distal pathway, Mo@W 2 N 3 follows the enzymatic pathway. • W@W 2 N 3 exhibits the lowest overpotential (η=0.059 V) and the highest catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu 55 and core–shell Cu-Ni-Pt ternary alloy clusters were constructed by DFT. • Adsorption of intermediate species and reaction mechanism of DRM on clusters were discussed. • Compared with Cu 55 , Cu-Ni-Pt clusters show much lower energy barrier in CH X activation. • Except for Hol2 site, Top1, Top2, Hol1 and Bri2 are all adsorption sites of the cluster for DRM. • The rate-determining step of DRM on Cu-Ni-Pt ternary alloy clusters is CO 2 * activation. Dry reforming of methane (DRM) can not only solve the problem of greenhouse gas emissions, but also be used as a precursor step for the production of clean energy. In this paper, based on Cu 55 cluster, core–shell Cu-Ni-Pt ternary alloy clusters were constructed by density functional theory (DFT). Based on theoretical calculation, the adsorption of intermediate species and reaction mechanism of DRM on clusters were discussed in detail. Compared with Cu 55 cluster, Cu-Ni-Pt ternary alloy clusters show much lower energy barrier in CH X activation, which indicates that the latter is much more suitable for DRM reaction than the former. The different species would be adsorbed on Top1, Top2, Hol1 and Bri2 site of the cluster. Hol2 was not the active adsorption site of DRM species. For Cu-Ni-Pt ternary alloy clusters, CH 4 decomposes into CH 3 *, and then CO 2 is directly activated into CO* and O*. CH 3 * collides with O* species to produce CH 3 O*, and CH 3 O* further decays H* to produce CH 2 O*. Two molecules H* in the system interact to form H 2 *. CH 2 O* continuously dissociates two H* and transforms into CO*. Finally, two H* are combined to form H 2 *. The rate-determining step of this reaction pathway is CO 2 * activation. [ABSTRACT FROM AUTHOR]

• Metal doping with oxide magnesium (M/MgO (M=Li, Al, K, Ca)) was constructed by DFT. • Functions of facets and doping on CO2 adsorption properties and mechanism were investigated. • CO2 adsorption on MgO(110) is more favorable than that on MgO(100). • Doping of metals improves MgO's structural stability and adsorption properties, in which K being the best. • Choice of crystal plane and doped metal enhances charge transfer between interfaces of M/MgO(110). In this work, metal doping with magnesium oxide (M/MgO (M=Li, Al, K, Ca)) was constructed by density functional theory (DFT) methods to investigate the functions of crystal plane and doping on CO 2 adsorption properties and mechanism. DFT calculations show that the appropriate crystal plane and the doping metal can improve the adsorption properties of MgO on CO 2 , and the effect of different planes and different types of doped metals on CO 2 adsorption properties varies significantly. CO 2 adsorption on the MgO(110) plane is more favorable than on the MgO(100) plane, exhibiting an adsorption energy of –1.834 eV. The structural stability and adsorption properties of MgO are enhanced through the doping of metals (Li, Al, K, Ca), with K being the superior one due to its adsorption energy of –2.148 eV. The selection of crystal plane and doped metal enhances charge transfer at interfaces, resulting in a noteworthy improvement in CO 2 adsorption on M/MgO(110) plane. Additionally, the adsorption mechanism transitions from physisorption to chemisorption on the MgO(110) plane. This work combines the dual modification of crystal plane and doped metal to provide some references for the experimental study of CO 2 adsorption by MgO. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Stability, adsorption configuration and electronic properties of CO 2 on M/C 2 N and M 2 /C 2 N were investigated by DFT. • M/C 2 N and M 2 /C 2 N exhibit high stability, while NiCo/C 2 N has the highest stability. • M/C 2 N has poor CO 2 adsorption properties, while NiCo/C 2 N has good CO 2 adsorption properties. • M 2 /C 2 N is more prone to CO 2 RR generation of C1 products than M/C 2 N. • The energy barrier analysis of C–C coupling reaction shows that NiCo/C 2 N is favorable to CO 2 RR. In the paper, the stability, adsorption configuration and activated electronic properties of CO 2 on the surfaces of C 2 N, single–atom–doped C 2 N (M/C 2 N), bi–atomic–metal–doped C 2 N (M 2 /C 2 N) were investigated by density functional theory (DFT). Calculations show that both M/C 2 N and M 2 /C 2 N exhibit high stability, in which NiCo/C 2 N has the highest stability. Based on the comparison of bond lengths and bond angles for adsorbed CO 2 , it indicates that M/C 2 N shows poor CO 2 adsorption properties, while NiCo/C 2 N has good CO 2 adsorption properties. Further studies on the generation of C1 products from CO 2 RR and C–C coupling reactions on M/C 2 N and M 2 /C 2 N materials were carried out. It was found that the outermost electron distribution and density of states of the transition metals lead to different pathways for C1 generation from CO 2 RR on the surfaces of Cu/C 2 N, Ni/C 2 N and Co/C 2 N. In particular, M 2 /C 2 N is more prone to CO 2 RR than M/C 2 N. Meanwhile, the energy barriers of C–C coupling reaction show that NiCo/C 2 N is favorable to CO 2 RR. In addition, the mechanism study of CO 2 RR generation of ethylene (C 2 H 4) on the surface of NiCo/C 2 N material is further discussed, which provides some support for the application of bimetallic atomic catalysts in CO 2 RR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrathin NiAl-LDHs (U-LDHs) nanosheets were prepared for photodegradation of methylene blue. • Thickness of U-LDHs is between 3 and 8 nm, with the specific surface area of 109 m2/g. • U-LDHs removed 92.42% of methylene blue, which is 40% higher than that of bulk LDHs. • U-LDHs is better to the separation and transfer of photogenerated carriers than bulk LDHs. • U-LDHs is conducive to adsorb oxygen to generate superoxide radicals, promoting photocatalysis. Ultrathin materials are widely used in various photocatalytic reactions due to their large specific surface area, multi-surface active sites, easy carrier separation and transport. In this work, ultrathin NiAl-layered double hydroxides (U-LDHs) nanosheets were prepared by a urea-assisted strategy for photocatalytic degradation of methylene blue. Atomic force microscopy (AFM) measurements show that the thickness of U-LDHs nanosheet is generally between 3 and 8 nm, with a wide pore size distribution and a high specific surface area (109 m2/g). U-LDHs nanosheets can remove 92.42% of methylene blue after 90 min light irradiation, which is nearly 40% higher than that of bulk NiAl-LDHs (B-LDHs). In addition, combined with photoelectric performance characterization and density functional theory calculation, it is confirmed that the U-LDHs nanosheets are much better to the separation and transfer of photogenerated carriers compared with the bulk LDHs. Besides, U-LDHs is conducive to adsorb oxygen to generate superoxide radicals, promoting the progress of photocatalytic reactions and significantly improving photodegradation performance. [ABSTRACT FROM AUTHOR]

• Monatomic transition metal M supported MoS 2 (M/MoS 2 , M=Co, Ni, Cu) was constructed. • Structural properties, molecular adsorption and the reaction mechanism for WGSR were investigated. • Doping transition metal can increase the charge transfer and reduce the band gap of M/MoS 2. • Potential WGSR mechanism is association mechanism, in which HCOO* intermediate plays leading role. • Supporting metal can effectively reduce the reaction energy barrier of WGS. In this paper, a two-dimensional M/MoS 2 material system was constructed by supporting transition metal atoms M (M=Co, Ni, Cu) on the surface of MoS 2. The structural properties, molecular adsorption and the reaction mechanism for water gas shift reaction (WGSR) were investigated based on DFT calculation. Compared with pristine MoS 2 , doping transition metal can make M/MoS 2 more stable because the charge transfer between metal and MoS 2 increases the polarization of Mo and S. The adsorption performance is significantly improved, which is conducive to the forward progress of the reaction. The band gap of materials is narrowed, which motivates MoS 2 transforms to metal phase. The supporting metal can increase the charge transfer and the number of active sites in the system, which can effectively reduce the reaction energy barrier of WGS and improve the catalytic activity. The most potential WGSR mechanism of the three materials is the association mechanism, in which the HCOO* intermediate plays the leading role. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Two structures (Sc–V Li−LiH and Mo–V Li−LiH) and original LiH were constructed for NRR by DFT. • Both Sc–V Li−LiH and Mo–V Li−LiH have excellent stability and electron activity. • The adsorption of N 2 by Sc and Mo atoms is significantly enhanced after doping. • The effective charge transfer of Sc–V Li−LiH and Mo–V Li−LiH can fully activate N 2. • Mo–V Li−LiH has higher NRR activity than Sc–V Li−LiH due to lower energy barrier of rate-determining step. In this work, density functional theory (DFT) was used to calculate the structure, charge transfer and electrocatalytic nitrogen reduction reaction (NRR) catalytic activity of Li-defected lithium hydride (LiH) by doping monatomic transition metal Sc (Sc–V Li−LiH) and Mo (Mo–V Li−LiH). The doping of monatomic Sc and Mo can effectively transfer and activate the electrons in the material to N 2 molecule. The Gibbs free energy study of the reaction path shows that the doped system can effectively reduce the free energy of NRR reaction and improve the hydrogenation reaction capacity of N 2. For Sc–V Li−LiH , the most potential path of NRR is the alternating mechanism, in which the rate-determining step is the formation of *NH 2 −*NH 2 with an reaction free energy of 1.326 eV, and the reaction free energy of the formation of *NNH in the initial reaction is only 0.235 eV. Mo–V Li−LiH tends to perform NRR by distal mechanism, and the reaction free energy of rate-determining step is only 0.714 eV, which has lower reaction free energy and higher catalytic activity than Sc–V Li−LiH. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mechanism of DRM on Cu 12 M (M = Cu, Fe, Co, Ni) nanoclusters was studied by DFT. • The charge in the core-shell structure is transferred to the shell atom through the core atom. • Fe, Co and Ni as core atoms enhance the structural stability of Cu 13 nanoclusters. • Cu 12 Ni is the most potential DRM catalyst due to the highest electronic activity. • The total energy barrier of DRM on Cu 12 Ni is the lowest. Dry reforming of methane (DRM) reaction can not only effectively solve the greenhouse effect, but also produce H 2 and CO, which are important raw materials and intermediates for Fischer-Tropsch synthesis. In this paper, the mechanism of DRM on Cu 12 M (M = Cu, Fe, Co, Ni) core-shell bimetallic nanoclusters was studied by density functional theory (DFT). The Mulliken charge distribution indicates that the charge in the core-shell structure is transferred to the shell atom (Fe, Co, Ni) through the core atom (Cu). The results of binding energy and bond length indicate that Fe, Co and Ni as core atoms enhance the structural stability of Cu 13 nanoclusters. The analysis of partial density of states (PDOS) and d -band center indicates that Cu 12 Ni is the most potential DRM catalyst due to the highest electronic activity. The mechanism study shows that Cu 13 , Cu 12 Co and Cu 12 Ni all react in the same path, while Cu 12 Fe takes another route. The rate-determining step is CH 3 * → CH 2 * + H*, and the total energy barrier of DRM on Cu 12 Ni nanocluster is relatively the lowest, which is the most cluster to catalytic DRM reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electronic, thermodynamic and H 2 adsorption performance of C 3 N materials were studied by DFT. • The structural stability of the defective C 3 N increased after embedding of Al and Li. • Li/V N -C 3 N has the best adsorption performance for H 2 among five C 3 N materials. • When adsorbing six H 2 , the absolute value of the adsorption energy reaches the maximum. • When adsorbing multiple H 2 , adsorption energy of four doped C 3 N materials first increases and then decreases. In this paper, density functional theory (DFT) was used to study the structural properties, charge transfer, thermodynamic stability and hydrogen storage properties of C 3 N two-dimensional materials and atomic defects C 3 N doped with Al and Li (Al/V N -C 3 N, Al/V C -C 3 N, Li/V N -C 3 N and Li/V C -C 3 N), respectively. The results show that Al/Li doping does not reduce the stability of C 3 N structure, and C 3 N, Al/V N -C 3 N, Al/V C -C 3 N and Li/V N -C 3 N have good thermal stability at room temperature (300 K). The calculation results of H 2 adsorption show that Li/V N -C 3 N has the best adsorption performance, and the average adsorption energy of single H 2 is −0.289 eV. When adsorbing multiple hydrogen molecules, the energy of the four doped C3N materials first increased from 0.2 eV to 0.5 eV and then decreased to 0.4 eV on average. The decrease is small, indicating that it was possible to adsorb more hydrogen. When adsorbing six hydrogen molecules, the absolute value of the adsorption energy reaches the maximum. Thus, four doped C 3 N materials, particular for Li/V N -C 3 N, have the potential to become new hydrogen storage materials. [ABSTRACT FROM AUTHOR]

• The reaction path of low temperature RWGS on M/C 2 N (M=Cu, Co, Fe) was studied by DFT. • After doping, electrons transfer from m to C 2 N and gather directionally on the surface of C 2 N. • Low-temperature RWGS on Cu/C 2 N and Co/C 2 N proceed to redox mechanism, while Fe/C 2 N tend to carboxyl mechanism. • The energy barrier of rate-determining step in redox mechanism for Cu/C 2 N is the lowest. The reaction path of low temperature reverse water gas reaction (RWGS) on M/C 2 N (M=Cu, Co, Fe) was studied by density functional theory (DFT). The results show that after doping, electrons transfer from M to C 2 N and gather directionally on the surface of C 2 N, which significantly changes the catalytic behavior of C 2 N. Because the increase of electronic activity reduces the reaction activation energy, it effectively promotes the RWGS on C 2 N at low temperature. We also found that the low-temperature RWGS on Cu/C 2 N and Co/C 2 N proceed according to the redox mechanism, while Fe/C 2 N tend to the carboxyl mechanism. Moreover, the energy barrier of rate-determining step in redox mechanism for Cu/C 2 N is the lowest, indicating that the low-temperature RWGS reaction is more likely to occur on this structure. [Display omitted] [ABSTRACT FROM AUTHOR]