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Herein, we reported a novel 2D BC2P monolayer with great potential as an anode material for lithium-ion batteries which has the diffusion energies of 0.26 and 0.87 eV and high theoretical capacity of 1018.8 mA g h−1, and as the material for CO2 adsorption, respectively.

Exploiting efficient and recyclable photocatalysts is a vital matter for environmental purification. Herein, cerium vanadate (CeVO4) sub-microspheres and silver nanowire (AgNW)@CeVO4 with core-shell architecture as photocatalysts are rationally constructed by hydrothermal approach. The AgNW@CeVO4 photocatalyst obtained by depositing CeVO4 on the surface of Ag NWs possess one dimensional continuous structure, which expand the optical absorption range and reduce the band gap of CeVO4 photocatalyst. Moreover, the resultant AgNW@CeVO4 photocatalyst demonstrates superior photocatalytic performance in the degradation of rhodamine B, methylene blue, and 4-nitrophenol pollutants upon solar light irradiation, compared with pure CeVO4. The excellent photocatalytic activity can be ascribed to the introduction of Ag NWs, which afford rapid charge transport channels and reservoir for the electrons in the AgNW@CeVO4 heterostructure to promote separation of electron–hole pairs. The first-principles investigations reveal increase of adsorption energy of oxygen molecules on the CeVO4 surface with the presence of Ag. Meanwhile, Ag NWs can further improve the photocatalytic efficiency of the AgNW@CeVO4 based on the plasmonic effect. More importantly, the good structural stability and recyclability of AgNW@CeVO4 are observed due to the strong synergistic effect, which ensures long-term usability of photocatalyst and great promise in water purification. This work can offer valuable reference into designs and construction of Ce-based heterojunction photocatalysts for environmental remediation.

Nitric oxide reduction to ammonia by electrocatalysis is the potential application in the elimination of smog and energy conversion. In this work, the feasibility of the application of two-dimensional metal borides (MBenes) in nitric oxide electroreduction reaction (NOER) was investigated through density functional theory calculations. Including the geometry and electronic structure of five kinds of MBenes, the adsorption of NO on the surface of these substrates, the selective adsorption of hydrogen protons during the hydrogenation process, and the overpotential in the electrocatalytic ammonia synthesis process. As a result, MnB exhibited the most favorable catalytic performance according to the associative pathways, which is thermodynamically performed spontaneously, and WB has a minimum overpotential of 0.37 V vs. RHE in the process of ammonia production according to the dissociative pathway. Overall, our work is the first to explore the electrocatalytic NO through the dissociative mechanism to synthesize ammonia in-depth and proves that MBenes are efficient NO electrocatalytic ammonia synthesis catalysts. These research results provide a new direction for the development of electrocatalytic ammonia synthesis experimentally and theoretically.

The practical applications of lithium sulfur battery is impeded by the lithium polysulfide shuttling and sluggish redox kinetics. To address the issues, herein, a multifunctional host is developed by the combination of nitrogen, phosphorus co-doped carbon fiber (NPCF) and CoS2 towards boost the soluble polysulfides adsorption and transformation. Benefiting from the NPCF originated from biomass cattail fibers, a high conductive network is provided, and shuttle effect is reduced due to the strong chemical interaction between abundant heteroatom polar sites and lithium polysulfides. Moreover, the electrocatalytic CoS2 on the carbon skeleton facilitate lithium polysulfides conversion and lithium sulfide deposition based on the density functional theory calculations and experiments. The efficient lithium polysulfides entrapment and subsequent electrocatalytic conversion improve dynamic stability during cycling, especially for rate capability. With these advantageous features, the electrode with NPCF/CoS2 host can deliver a good rate capability (903 and 782 mAh g−1 at 1C and 2C, respectively) and stable cycling performance with an ultra-low capacity decay of 0.014% per cycle at 1C. Notably, the cell can achieve a high areal capacity of 4.96 mA h cm−2 under an elevated sulfur loading of 5.0 mg cm−2. Overall, the improvement on the electrochemical performance ascertains the validity of the design strategy based on synergy engineering, which is a highly suitable approach for energy storage and conversion application.

CO2 is a representative prototype model in energy and environmental fields. Many factors for CO2 capture and activation have been investigated extensively but the research on the influence of thermal conductivity is still absence. We herein have calculated many properties, including dipole moment, electric structure, and adsorption energies, on Pt doped graphene and 2D BC3N2 substrates and served the thermal conductivity as the bridge. Our results have demonstrated that the lower (higher) thermal conductivity for 2D BC3N2 (graphene) corresponds to larger (lower) dipole moment, which is beneficial for CO2 activation (capture) process. Our research have not only revealed the dominant role of heat conductivity for CO2 capture and activation, but also paved the way for further catalyst design of various areas.

The metastable character enables the low intercalation/conversion reaction energy and greatly promotes the fast pseudocapacitive storage mechanism, leading to the high-rate performance of microsized FeCN2@NC.

In this study, the key findings are that the para doped Mn2@Ir(100) catalyst affords excellent NH3 selectivity and NRR activity with an extremely low free energy barrier of 0.36 eV.

A unique trigonal bipyramidal cage-based Zn(ii)-MOF built from a linear trinuclear pin-wheel cluster and a triangular trinuclear cluster was prepared and shows a moderate gas adsorption amounts and high selectivities towards C2Hn/CH4 and C2H2/CO2.

A good-performance and low-cost electrocatalyst Ni–rGO/CeO2 has been achieved due to the increased oxygen vacancies and active sites brought about by the synergistic effect of rGO decoration and Ni doping.

To reduce the greenhouse effect caused by the surgery of nitrogen-oxides concentration in the atmosphere and develop a future energy carrier of renewables, it is very critical to develop more efficient, controllable, and highly sensitive catalytic materials. In our work, we proposed that nitric oxide (NO), as a supplement to N2 for the synthesis of ammonia, which is equipped with a lower barrier. And the study highlighted the potential of CeO2 (111) nanosheets with La doping and oxygen vacancy (OV) as a high-performance, controllable material for NO capture at the site of Vo site, and separation the process of hydrogenation. We also reported that the Eads of -1.12 eV with horizontal adsorption and the Bader charge of N increasing of 0.53|e| and O increasing of 0.17|e| at the most active site of reduction-OV predicted. It is worth noting that ΔG of NORR (NO reduction reaction) shows good performance (thermodynamically spontaneous reaction) to synthesize ammonia and water at room temperature in the theoretical calculation.

The stability of two-dimensional (2D) metal-organic frameworks (MOFs) and their physical and chemical properties for potential applications are contentious so far. We herein investigated geometric, electronic, and magnetic properties of...

The photocatalytic nitrogen reduction reaction (NRR) has mild reaction conditions and only requires sunlight energy as a driving force to replace the traditional ammonia synthesis method. We herein investigate the catalytic activity and selectivity on Penta-B2C for NRR by using density functional theory calculations. Penta-B2C is a semiconductor with an indirect bandgap (2.328 eV) and is kinetically stable based on molecular dynamic simulations. The optical absorption spectrum of Penta-B2C is achieved in the ultraviolet and visible range. Effective light absorption is more conducive to generate photo-excited electrons and improving photocatalytic performances. Rich B atoms as activation sites in Penta-B2C facilitate capturing N2. The activated N2 molecule prefers the side-on adsorption configuration on Penta-B2C, which facilitates the subsequent reduction reaction. Among considered NRR mechanisms on Penta-B2C, the best pathway prefers the enzymatic mechanism, only required a low onset potential of 0.23 V. The hydrogen evolution reaction is inhibited when the hydrogen adsorption concentration is increased or N2 molecules first occupy the adsorption sites. Our results indicate Penta-B2C is a highly reactive and selective photocatalyst for NRR. Our work provides theoretical insights into the experiments and has guiding significance to synthesize efficient NRR photocatalysts.

NiWO4 microflowers with a large surface area up to 79.77 m2·g-1 are synthesized in situ via a facile coprecipitation method. The NiWO4 microflowers are further decorated with multi-walled carbon nanotubes (MWCNTs) and assembled to form composites for NH3 detection. The as-fabricated composite exhibits an excellent NH3 sensing response/recovery time (53 s/177 s) at a temperature of 460 °C, which is a 10-fold enhancement compared to that of pristine NiWO4. It also demonstrates a low detection limit of 50 ppm; the improved sensing performance is attributed to the porous structure of the material, the large specific surface area, and the p-n heterojunction formed between the MWNTs and NiWO4. The gas sensitivity of the sensor based on daisy-like NiWO4/MWCNTs shows that the sensor based on 10 mol % (MWN10) has the best gas sensitivity, with a sensitivity of 13.07 to 50 ppm NH3 at room temperature and a detection lower limit of 20 ppm. NH3, CO2, NO2, SO2, CO, and CH4 are used as typical target gases to construct the NiWO4/MWCNTs gas-sensitive material and study the research method combining density functional theory calculations and experiments. By calculating the morphology and structure of the gas-sensitive material NiWO4(110), the MWCNT load samples, the vacancy defects, and the influence law and internal mechanism of gas sensitivity were described.

Ammonia (NH3) is considered an attractive candidate as a clean, highly efficient energy carrier. The electrocatalytic nitrogen reduction reaction (NRR) can reduce energy input and carbon footprint; therefore, rational design of effective electrocatalysts is essential for achieving high-efficiency electrocatalytic NH3 synthesis. Herein, we report that the enzymatic mechanism is the more favourable pathway for NRR, due to lower limiting potential (−0.44 V), lower free energy (only 0.02 eV) of the first hydrogenation step (*N–N to *NH–N), and more electron transfer from Fe2B2 to the reaction species. In addition, both vacancies and dopants can be helpful in reducing the reaction energy barrier of the potential-determining step. Therefore, we have demonstrated that Fe2B2 is a potential new candidate for effective NRR and highlighted its potential for applications in electrocatalytic NH3 synthesis.

In this paper, a novel BC3N2 monolayer has been found with a graphene-like structure using the developed particle swarm optimization algorithm in combination with ab initio calculations. The predicted structure meets the thermodynamical, dynamical, and mechanical stability requirements. Interestingly, the BC3N2 plane shows a metallic character. Importantly, BC3N2 has an in-plane stiffness comparable to that of graphene. We have also investigated the adsorption characteristics of CO2 on pristine monolayer and Mo functionalized monolayer using density functional theory. Subsequently, electronic structures of the interacting systems (CO2 molecule and substrates) have been preliminarily explored. The results show that Mo/BC3N2 has a stronger adsorption capacity towards CO2 comparing with the pristine one, which can provide a reference for the further study of the CO2 reduction mechanism on the transition metal-functionalized surface as well as the new catalyst’s design.

In order to reduce the greenhouse effect caused by the rapid increase of CO2 concentration in the atmosphere, it is necessary to develop more efficient, controllable, and highly sensitive adsorbing materials. In this study, the adsorption behavior of CO2 on BC3 nanosheets under an external electric field was explored based on density functional theory (DFT). It was found that CO2 experienced a transition from physisorption to chemisorption in the electric field range of 0.0060-0.0065 a.u.. In addition, the adsorption/desorption of CO2 is reversible and can be precisely controlled by switching on/off at the electric field of 0.0065 a.u.. The selective adsorption of CO2/H2/CH4 by BC3 can also be used to realize gas separation and purification under different electric fields. This study highlighted the potential application of BC3 nanosheets as a high-performance, controllable material for CO2 capture, regeneration, and separation in an electric field.

Polysulfides can be captured rapidly by defects, which possess strong catalytic redox abilities. Species of defects have important influence on rate performance of metal-sulfur electrodes. However, catalytic reaction mechanisms have not been explored in depth. This paper focuses on comparing differences between intrinsic defect carbon materials (IDC) and external introduced defect carbon materials (EIDC) in promoting polysulfide redox abilities and exploring catalytic redox reaction mechanism deeply. Results show that IDC have stronger catalytic redox reaction abilities than EIDC, which is mainly due to stable C–S bonds on surface of IDC. After cycling, C–S bond contents in IDC electrodes maintain more than 70 %. During cycling process, C–S bonds can quickly adsorb polysulfides and promote their conversion into final products, thereby achieving high rate performance. Weak catalytic redox abilities of EIDC electrodes is mainly due to loss of C–S bonds. When the current density is 5C, capacities of IDC electrodes is twice as much as that of EIDC electrodes. Good rate performance of IDC electrodes reflects important roles of stable C–S bonds in promoting redox reaction of polysulfides, which has important research significance for preparation of carbon-based composite electrodes.

The accurate design and systematic engineering of MOFs is a large challenge due to the randomness of the synthesis process. Isoreticular chemistry provides a powerful approach for the regulation of pore environment in a more predictable and precise way to systematically control gas/vapor adsorption performances. Herein, utilizing an effective strategy of altering the "pillared" motifs of pillared layer structures, three isoreticular ultramicroporous MOFs were successfully constructed. Combined with the reported parent MOFs and two other recorded isoreticular MOFs modified with -NH

The synthesis of ammonia (NH3 ) through the electrochemical reduction of molecular nitrogen (N2 ) is a promising strategy for significantly reducing energy consumption compared to traditional industrial processes. Herein, we report the design of a series of monovacancy and divacancy defective graphenes decorated with single 3d transition metal atoms (TM@MVG and TM@DVG; TM=Sc-Zn) as electrocatalysts for the nitrogen-reduction reaction (NRR) aided by density functional theory (DFT) calculations. By comparing energies for N2 adsorption as well as the free energies associated with *N2 activation and *N2 H formation, we successfully identified V@MVG, with the lowest potential of -0.63 V, to be an effective catalytic substrate for the NRR in an enzymatic mechanism. Electronic properties, including Bader charges, charge density differences, partial densities of states, and crystal orbital Hamilton populations, are further analyzed in detail. We believe that these results help to explain recent observations in this field and provide guidance for the exploration of efficient electrocatalysts for the NRR.

In this paper, the process of ammonia borane (AB) hydrolysis generate H2 on the transition metal Fe@Co core-shell structure has been obtained. According to the different roles played by H2O molecules and the number of H2O molecules involved, there are three schemes of reaction paths. Route I does not involve the dissociation of H2O molecules and all H atoms come from AB. Moreover, the H2O molecule has no effect on the breaking of the B H bond or the N H bond. The reaction absorbs more heat during the formation of the second and third H2 molecules. Route II includes the dissociation of H2O molecules and the cleavage of B H or N H bonds, respectively, and the reaction shows a slight exotherm. Route III started from the break of the B N bond and obtained 3H2 molecules through the participation of different numbers of H2O molecules. After multiple comparative analyses, the optimal hydrolysis reaction path has been obtained, and the reaction process can proceed spontaneously at room temperature.

A new porous metal-organic framework, [Pb5(OAc)7(nIm)3]n (1), has been successfully synthesized by employing 2-nitroimidazole ligand and Pb2+ ion. 1 contains novel the ribbon-shaped Pb-O SBU and reveals a 2D porous framework with a 1D tubular channel. Due to the existence of the electronegative O atom of nitro group and Lewis acid metal ion in the channel, 1 shows moderate CO2 adsorption uptake of 25.8 cm3 cm− 1 at 298 K and 760 mmHg, and adsorption sites are also confirmed by GCMC simulations. Moreover, the electronic structures and luminescence properties of 1 was investigated. This work displays an effective approach to enrich multifunctional porous Pb-MOFs.

Using the global particle-swarm optimization method and density functional theory, we predict a new stable two-dimensional layered material: MgSiP2 with a low-buckled honeycomb lattice. Our HSE06 calculation shows that MgSiP2 is an indirect-gap semiconductor with a band-gap of 1.20 eV, closed to that of bulk silicon. More remarkably, MgSiP2 exhibits worthwhile anisotropy along with electron and hole carrier mobility. A ultrahigh electron mobility is even up to 1.29 × 104 cm2 V−1 s−1, while the hole mobility is nearly zero along the a direction. The large difference of the mobility between electron and hole together with the suitable band-gap suggest that MgSiP2 may be a good candidate for solar cell or photochemical catalysis material. Furthermore, we explore MgSiP2 as an anode for sodium-ion batteries. Upon Na adsorption, the semiconducting MgSiP2 transforms to a metallic state, ensuring good electrical conductivity. A maximum theoretical capacity of 1406 mAh/g, a small volume change (within 9.5%), a small diffusion barrier (∼0.16 eV) and low average open-circuit voltages (∼0.15 V) were found for MgSiP2 as an anode for sodium-ion batteries. These results are helpful to deepen the understanding of MgSiP2 as a nanoelectronic device and a potential anode for Na-ion batteries.

Constructing 3D multifunctional conductive framework as stable sulfur cathode contributes to develop advanced lithium-sulfur (Li-S) batteries. Herein, a freestanding electrode with nickel foam framework and nitrogen doped porous carbon (PC) network is presented to encapsulate active sulfur for Li-S batteries. In such a mutually embedded architecture with high stability, the interconnected carbon network and nickel foam matrix can expedite ionic/electronic transport and sustain volume variations of sulfur. Furthermore, rationally designed porous structures provide sufficient internal space and large surface area for high active sulfur loading and polar polysulfides anchoring. Benefiting from the synergistic superiority, the Ni/PC-S cathode exhibits a high initial capacity of around 1200 mAh/g at 0.2 C, excellent rate performance, and high cycling stability with a low decay rate of 0.059% per cycle after 500 cycles. This work provides a useful strategy to exploit freestanding porous framework for diverse applications.

Using particle swarm optimization (PSO) methodology for crystal structure prediction, we predicted a novel two-dimensional (2D) monolayer of silicide diphosphorus compound: SiP2, which exhibits good stability as examined via cohesive energy, mechanical criteria, molecular dynamics simulation and all positive phonon spectrum, respectively. The SiP2 monolayer is an indirect semiconductor with the band gap as 1.8484 eV (PBE) or 2.681 eV (HSE06), which makes it more advantageous for high-frequency-response optoelectronic materials. Moreover, the monolayer is a relatively hard auxetic material with negative Possion’s ratios, and also possesses a ultrahigh carrier mobility (1.069 × 105 cm2 V−1 s−1) which is approximately four times the maximum value in phosphorene and comparable to the value of graphene and CP monolayers. Furthermore, the effects of strains on band structures and optical properties of SiP2 monolayer have been studied, as well as CO2 molecules can be strongly chemically adsorbed on the SiP2 monolayer. A semiconductor-to-metal transition for −9.5% strain ratio case and a huge optical absorption capacity on the order of 106 cm−1 in visible region present. These theoretical findings endow SiP2 Monolayer to be a novel 2D material holding great promises for applications in high-performance electronics, optoelectronics, mechanics and CO2 capturing material.

The adsorption and activation of gas molecules are investigated substantially in solid-gas heterogeneous catalysis. Here we investigated the interaction between gas molecules and unique two-dimensional monolayer Au (111) structure using density functional theory. It is found that CO2, H2O, N2 and CH4 molecules are weakly adsorbed on the surface with the adsorption energies between −0.150 and −0.250 eV due to van der Waals interaction. While CO, NO, NO2, and NH3 molecules are adsorbed more stably with the adsorption energies between −0.300 and −0.470 eV. Especially, the bond length of CO is stretched by 0.038 A and the bond angle of NO2 is obviously enlarged by 10.460°. The activation originates from the rearrangement of molecule orbitals and the orbitals hybridization between the partial orbitals of gas molecules and Au-5d orbitals. The fundamental analyses of adsorption mechanism and electronic properties may provide guidance for the applications of two-dimensional monolayer metal catalysis. PACSnumbers 73.22.-f, 73.61.-r

The influence of Mn, Fe, Si vacancies and Al-doped 4H–SiC on the electronic structures and magnetic properties are studied by first principles calculations. The results indicate both Mn and Fe monodoped can induce magnetism. Additionally, the phenomenon of ferromagnetism is observed in (Mn, Fe)-codoped 4H–SiC system, mainly contributed by Mn and Fe atoms. The ferromagnetic mechanism is that C atoms act as a medium between Mn atom and Fe atom, forming a Mn–C–Si–C–Fe coupling chain. The Si vacancies have a weaker effect on inducing ferromagnetism and Al atom doped has no obvious effect on the magnetic properties. Our study provides an effective method of tuning magnetism in 4H–SiC.

Single atom catalysts (SACs) with isolated metal atoms dispersed on supports exhibit distinctive performances for electrocatalysis reactions. The designable realization of well-dispersed single metal atoms is still a great challenge owing to their ease of aggregation. Here, Mo single atomic sites (Mo-N3C) combined with some ultrasmall Mo2C/MoN clusters (Mo-SA/Mo2C-MoN-Cs, mean diameter

The separation of CO2 or CH4 from a CO2/CH4 mixture has drawn great attention in relation to solving air pollution and energy shortage issues. However, research into using bifunctional catalysts to separate CO2 and CH4 under different conditions is absent. We have herein designed a novel B-doped two-dimensional InSe (B@2DInSe) catalyst, which can chemically adsorb CO2 with covalent bonds. B@2DInSe can separate CO2 and CH4 in different electric fields, which originates from different regulation mechanisms by an electric field (EF) on the electric properties. The hybridization states between CO2 and B@2DInSe near the Fermi level have experienced gradual localization and eventually merged into a single narrow peak under an increased EF. As the EF further increased, the merged peak shifted towards higher energy states around the Fermi level. In contrast, the EF mainly alters the degree of hybridization between CH4 and B@2DInSe at states far below the Fermi level, which is different from the CO2 situation. These characteristics can also lead to perfect linear relationships between the adsorption energies of CO2/CH4 and the electric field, which may be beneficial for the prediction of the required EF without large volumes of calculations. Our results have not only provided novel clues for catalyst design, but they have also provided deep understanding into the mechanisms of bifunctional catalysts.

The rational design and construction of noble-metal-free electrocatalysts with high activity and robust durability for oxygen evolution reactions (OERs) have aroused immense interest in the past decades, but challenges remain. Herein, a reduction-induced dissolution–recrystallization (RIDR) strategy was developed to fabricate a defect-rich yolk–shell Prussian-blue analogue (YS-PBA) by a solvothermal process in isopropyl alcohol (IPA) in the presence of polyvinylpyrrolidone (PVP). The experimental result indicated that the defect-rich YS-PBA was formed via phase transformation from Co3[FeIII(CN)6]2 to Co2FeII(CN)6 induced by the reduction potential of the IPA-PVP couple. The newly synthesized YS-PBA exhibited outstanding OER performance with a low overpotential of 293 mV to deliver a current density of 10 mA cm−2 and long-term durability (120 h) in alkaline media. Both experimental and density functional theory (DFT) results unveiled that the defects formed in YS-PBA cause a dramatic positive effect on the improvement of the OER activity.

Two-dimensional (2D) metal–organic frameworks (MOFs) serve as emerging electrocatalysts due to their high conductivity, chemical tunability, and accessibility of active sites. We herein proposed a series of 2D MOFs with different metal atoms and organic linkers with the formula M3C12X12 (M = Cr, Mo, and W; X = NH, O, S, and Se) to design efficient nitrogen reduction reaction (NRR) electrocatalysts. Our theoretical calculations showed that metal atoms in M3C12X12 can efficiently capture and activate N2 molecules. Among these candidates, W3C12X12 (X = O, S, and Se) show the best NRR performance due to their high activity and selectivity as well as low limiting potential (−0.59 V, −0.14 V, and −0.01 V, respectively). Moreover, we proposed a d-band center descriptor strategy to screen out the high activity and selectivity of M3C12X12 for the NRR. Therefore, our work not only demonstrates a class of promising electrocatalysts for the NRR but also provides a strategy for further predicting the catalytic activity of 2D MOFs.

Polysulfides (Li2Sx) have become key points that limit capacity improvement of lithium-sulfur batteries because of their high solubility. Oxygen-containing functional groups (such as C–O–H, C–O–C and C O) can effectively relieve a large amount of polysulfide dissolution due to their strong polarity. However, their types and contents on polysulfide-capturing abilities are still unknown. Therefore, three kinds of electrodes containing different contents of hydroxyl (C–O–H), ether (C–O–C) and carbonyl (C O) groups on carbon surface are controlled by changing pyrolysis times of dandelion. Electrochemical performance of lithium-sulfur batteries is tested to analyze influence of these groups on polysulfide-capturing abilities. It is discovered that C O and C–O–H groups can obviously inhibit shuttle effects of polysulfides during their initial production. In addition, a large number of C O bonds are converted to C–O–H bonds. More C–O–H bonds facilitate reversible capture of polysulfides and improve capacities. The introduction of C–O–C groups is not suitable for capturing more polysulfides rapidly and the appearance of ether groups limits conversion process of C–O–H groups. Both S load and discharging/charging process can effectively regulate evolution of three valence bonds, which is conducive to improving rate performance of lithium-sulfur batteries.

As electrodes, two-dimensional materials show special advantages including the infinite planar lengths, broad electrochemical window, large surface–volume ratio, and much exposed active sites. In theory, the two-dimensional materials consist of the elements with high electronegativity may absorb more Na atoms, resulting in a high battery storage capacity. Based on the above idea, we selected the two dimensional metallic PS2 with 1T-Type structure as an anode material, and explored its potential applications as an electrode material for Na-ion battery through first-principle calculations. As we expected, when two dimensional PS2 is used as an anode in Na-ion battery, it can adsorb maximum three layers of sodium atoms on both sides of the monolayer, resulting in a maximum theoretical capacity of 1692 mAh/g. Furthermore, it also possesses a rather small sodium diffusion barrier of 0.17 eV, a low average open-circuit voltage of 0.18 V, and a relatively small lattice changes within 13% during the intercalation of Na. These results suggested that the two dimensional PS2 is a potentially excellent Na-ion battery anode. Our idea of designing two-dimensional anode materials with high storage capacity may provide some references for designing the next generation anode materials of metal-ion batteries.

Herein, we have investigated the adsorption behavior of gas molecules, including C2H2, H2S, SO2, SO3, and O2, on FeN3-doped graphene (FeN3-gra). The change of geometric stability, electric structure, and magnetic properties is discussed comprehensively. The results have demonstrated that the stability of the substrate is enhanced by the hybridization between Fe and N atoms in FeN3-gra. Besides, the Fe dopant can enhance the adsorption ability of gases on graphene. The gas molecules all exhibit high binding strength on FeN3-gra especially for SO3 with the adsorption energy of -3.30 eV. The mechanism of interaction between gases and substrate is investigated based on the charge density difference and density of states, which can clarify the distribution of electrons and magnetic moments. Moreover, the high stability and sensitivity of FeN3-gra are promising characters for gas detection. Our research has paved the way for the application of the graphene-based material in gas sensor and electronic instrument.