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1.
Recently, nonmetal doping has exhibited its great potential for boosting the hydrogen evolution reaction (HER) of transition-metal (TM)-based electrocatalysts. To this end, this work overviews the recent achievements made on the design and development of the nonmetal-doped TM-based electrocatalysts and their performance for the HER. It is also shown that by rationally doping nonmetal elements, the electronic structures of TM-based electrocatalysts can be effectively tuned and in turn the Gibbs free energy of the TM for adsorption of H* intermediates (Δ GH*) optimized, consequently enhancing the intrinsic activity of TM-based electrocatalysts. Notably, we highlight that concurrently doping two nonmetal elements can continuously and precisely regulate the electronic structures of the TM, thereby maximizing the activity for HER. Moreover, nonmetal doping also accounts for enhancing the physical properties of the TM (i.e. surface area). Therefore, nonmetal doping is a robust strategy for simultaneous regulation of the chemical and physical features of the TM. 相似文献
2.
Molybdenum disulfide (MoS 2) has been widely studied as a potential earth‐abundant electrocatalyst for the hydrogen‐evolution reaction (HER). Defect engineering and heteroelemental doping are effective methods to enhance the catalytic activity in the HER, so exploring an efficient route to simultaneously achieve in‐plane vacancy engineering and elemental doping of MoS 2 is necessary. In this study, Zinc, a low‐cost and moderately active metal, has been used to realize this strategy by generation of sulfur vacancies and zinc doping on MoS 2 in one step. Density functional theory calculations reveal that the zinc atoms not only lower the formation energy of S vacancies, but also help to decrease Δ GH of S‐vacancy sites near the Zn atoms. At an optimal zinc‐reduced MoS 2 (Zn@MoS 2) example, the activated basal planes contribute to the HER activity with an overpotential of ?194 mV at 10 mA cm ?2 and a low Tafel slope of 78 mV/dec. 相似文献
4.
We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on a two-dimensional (2D) noble-metal-free titanium disulfide (TiS 2) monolayer, which belongs to the exciting family of transition metal dichalcogenides (TMDCs). Our theoretical investigation to probe the HER and OER on both the H and T phases of 2D TiS 2 is based on electronic-structure calculations witihin the framework of density functional theory (DFT). Since TiS 2 is the lightest compound among the group-IV TMDCs, it is worth exploring the catalytic activity of a TiS 2 monolayer through the functionalization at the anion (S) site, substituting with P, N, and C dopants as well as by incorporating single sulfur vacancy defects. We have investigated the effect of functionalization and vacancy defects on the structural, electronic, and optical response of a TiS 2 monolayer by determining the density of states, work-function, and optical absorption spectra. We have determined the HER and OER activities for the functionalized and defective TiS 2 monolayers based on the reaction coordinate, which can be constructed from the adsorption free energies of the intermediates (H*, O*, OH* and OOH*, where * denotes the adosrbed state) in the HER and OER mechanisms. Finally, we have shown that TiS 2 monolayers are emerging as a promising material for the HER and OER mechanisms under the influence of functionalization and defects. 相似文献
5.
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 N 2 for the synthesis of ammonia, which is equipped with a lower barrier. And the study highlighted the potential of CeO 2(111) nanosheets with La doping a... 相似文献
6.
Exploring highly efficient electrocatalysts and understanding the reaction mechanisms for hydrogen electrocatalysis,including hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) in alkaline media are conducive to the conversion of hydrogen energy.Herein,we reported a new strategy to boost the HER/HOR performances of ruthenium (Ru) nanoparticles through nitrogen (N) modification.The obtained N-Ru/C exhibit remarkable catalytic performance,with normalized HOR exchange current d... 相似文献
7.
Among the widely studied 2D transition metal dichalcogenides (TMDs), MoTe 2 has attracted special interest for phase-change applications due to its small 2H-1T′ energy difference, yet a large scale phase transition without structural disruption remains a significant challenge. Recently, an interesting long-range phase engineering of MoTe 2 has been realized experimentally by Ca 2N electride. However, the interface formed between them has not been well understood, and moreover, it remains elusive how the presence of Ca 2N would affect the basal plane reactivity of MoTe 2. To address this, we performed density functional theory (DFT) calculations to investigate the potential of tuning the phase stability and chemical reactivity of a MoTe 2 monolayer via interacting with Ca 2N to form a van der Walls heterostructure. We found that the contact nature at the 2H-MoTe 2/Ca 2N interface is Schottky-barrier-free, allowing for the spontaneous electron transfer from Ca 2N to 2H-MoTe 2 to make it strongly n-type doped. Moreover, Ca 2N doping significantly lowers the energy of 1T′-MoTe 2 and dynamically triggers the 2H-to-1T′ transformation. The Ca 2N-induced phase modulation can also be applied to tune the phase energetics of MoS 2 and MoSe 2. Furthermore, using H adsorption as the testing ground, we also find that the H binding on the basal plane of MoTe 2 is enhanced after forming heterostructure with Ca 2N, potentially providing basis for surface modification and other related catalytic applications. 相似文献
8.
Lipid rafts are a dynamic microdomain structure found in recent years, enriched in sphin-golipids, cholesterol and particular proteins. The change of structure and function of lipid rafts could result in many diseases. In this work, the monolayer miscibility behavior of mixed systems of Egg-Sphingomyelin (ESM) with 1, 2-dioleoyl-sn-glycero-3-phosphocholine was in-vestigated in terms of mean surface area per molecule and excess molecular area ΔA ex at certain surface pressure, surface pressure and excess surface pressure Δπ ex at certain mean molecular area. The stability and compressibility of the mixed monolayers was assessed by the parameters of surface excess Gibbs free energy ΔG ex, excess Helmholtz energy ΔH ex and elasticity. Thermodynamic analysis indicates ΔA ex and Δπe ex in the binary systems with positive deviations from the ideal behavior, suggesting repulsive interaction. The max-imum of ΔG ex and ΔH ex was at the molar fraction of ESM of 0.6, demonstrating the mixed monolayer was more unstable. The repulsive interaction induced phase separation in the monolayer 相似文献
9.
Electrocatalytic ammonia synthesis under mild conditions is an attractive and challenging process in the earth's nitrogen cycle, which requires efficient and stable catalysts to reduce the overpotential. The N 2 activation and reduction overpotential of different Ti 3C 2O 2-supported transition metal (TM) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, Cd, and Au) single-atom catalysts have been analyzed in terms of the Gibbs free energies calculated using the density functional theory (DFT). The end-on N 2 adsorption was more energetically favorable, and the negative free energies represented good N 2 activation performance, especially in the presence Fe/Ti 3C 2O 2 (?0.75 eV). The overpotentials of Fe/Ti 3C 2O 2, Co/Ti 3C 2O 2, Ru/Ti 3C 2O 2, and Rh/Ti 3C 2O 2 were 0.92, 0.89, 1.16, and 0.84 eV, respectively. The potential required for ammonia synthesis was different for different TMs and ranged from 0.68 to 2.33 eV. Two possible potential-limiting steps may be involved in the process: (i) hydrogenation of N 2 to *NNH and (ii) hydrogenation of *NH 2 to ammonia. These catalysts can change the reaction pathway and avoid the traditional N–N bond-breaking barrier. It also simplifies the understanding of the relationship between the Gibbs free energy and overpotential, which is a significant factor in the rational designing and large-scale screening of catalysts for the electrocatalytic ammonia synthesis. 相似文献
10.
The essential participation of agostic interactions in C−H bond activation, cyclometallation and other catalytic processes has been widely observed. To quantitatively evaluate the Mo−H−C agostic interaction in the Mo β/γ- agostomers [CpMo(CO) 2(P iPr 3)] + ( Mo , 1 and Mo , 2 ) and the Mn−H−C agostic interaction in the Mn α/ϵ-agostomers [(C 6H 9]Mo(CO) 3] ( Mn , 1 and Mn , 2 ), the comprehensive density functional theory (DFT) theoretical investigations were performed. Results indicated that the Mo β-agostomer 1 is only favorable by 0.5 kcal mol −1 than Mo γ-agostomer 2 , and the Gibbs barrier for their interconversion was 9.1 kcal mol −1. A slightly higher Gibbs barrier of 12.7 kcal mol −1 for the isomerization between the Mn α/ϵ-agostomers was also obtained. The relatively strong agostic interactions in Mo β-agostomer 1 and Mn α-agostomer 1 were further verified by the AIM (Atoms-In-Molecules) analyses and the NAdOs (natural adaptive orbitals) analyses. The findings on the agostic interaction presented in this study are believed to benefit the understandings of the agostic interaction involved catalytic processes and to promote the development of new organometallic complexes. 相似文献
11.
The hydrogen evolution effect of ZrS 2 carrier loaded with transition metal single-atom (SA) was explored by first-principles method. ZrS 2 was constructed with transition metal single-atom and dual-atom. The structure–activity relationship of supported single-atom catalysts was described by electronic properties and hydrogen evolution kinetics. The results show that the ZrS 2 carrier-loaded atomic-level catalysts are more likely to occur in acidic environments, where the Mo SA load has a higher hydrogen precipitation capacity than the Pt SA. In the case of dual-atom adsorption, most of the hydrogen reduction processes are higher than that of single atom loading, which indicates that the outer orbital hybridization is more likely to lead to the interfacial charge recombination of the catalyst. Thereinto, Ni/Pt @ZrS 2 has the lowest Gibbs free energy (0.08 eV), and the synergistic effect of transition metals induces the deviation of the center of the d-band from the Fermi level and improves the dissociation ability of H ions. The design provides a new catalytic model for the HER and provides some ideas for understanding the two-site catalysis. 相似文献
12.
Non-metal-based single-atom catalysts (SACs) offer low cost, simple synthesis methods, and effective regulation for substrates. Herein, we developed a simplified pressurized gas-assisted process, and report the first non-metal single-atom phosphorus with atomic-level dispersion on unique single-crystal Mo 2C hexagonal nanosheet arrays with a (001) plane supported by carbon sheet (SAP-Mo 2C-CS). The SAP-Mo 2C-CS is structurally stable and shows exceptional electrocatalytic activity for the hydrogen evolution reaction (HER). A so-called high-active “window” based on the active sites of P atoms and their adjacent Mo atoms gives a Δ GH* close to zero for hydrogen evolution, which is the most ideal Δ GH* reported so far. Meanwhile, the moderate d-band center value of SAP-Mo 2C-CS can be also used as an ideal standard value to evaluate the HER performance in non-metal-based SACs. 相似文献
13.
为了研发高效、稳定的电解水催化剂,我们以氧空位和磷掺杂为基础,通过原位浸泡生长和两步热处理的方法,在泡沫铁上合成具有氧空位和磷掺杂的纳米花结构作为析氢反应(HER)和析氧反应(OER)双功能电催化剂。CoFe 2O 4已被报道为一种很有前途的OER和氧还原反应(ORR)电催化剂,然而CoFe 2O 4在HER中表现出电导率差、电催化反应慢的特性。CoFe 2O 4中氧空位(Ov)的形成可以有效调控催化剂表面的电子结构,有助于产生更多的缺陷和空位,从而提高OER的活性。随后,引入磷原子填充在空位中,制备的P-Ov-CoFe 2O 4/IF在碱性电催化测试中展现出优异的HER和OER性能,在10 mA·cm -2电流密度下HER和OER过电位仅为54和191 mV,Tafel斜率分别为57和54 mV·dec -1,并具有良好的循环稳定性。 相似文献
14.
For the first time, the energy of combustion Δ c U of crystalline triphenylantimony bis(acetophenoneoximate) Ph 3Sb(ONCPhMe) 2 has been measured at T = 298.15 K using the isothermal combustion calorimeter with a stationary bomb. The standard molar enthalpy of combustion Δ c Hº, the standard molar enthalpy Δ f Hº, and free Gibbs energy Δ f Gº of formation of the above oximate have been calculated. 相似文献
17.
A method to determine the standard Gibbs free energy for the transfer, Δ G° tr, of a highly hydrophilic metal ion from an aqueous solution, W, in the presence of high concentration of H + to an organic solution, O, was proposed based on the theoretical consideration of the distribution process of ions between W and O. The usefulness of the proposed method was verified experimentally by comparing Δ G° tr of Mg 2+ determined by the method with that obtained by voltammetry for the ion transfer at the W|O interface. The O examined were nitrobenzene (NB) and 1,2-dichloroethane (DCE). By applying the proposed method, Δ G° tr of NpO 2+, UO 22+, NpO 22+ and PuO 22+ from an acidic W to NB were determined. 相似文献
18.
Internal energy difference, Δ E s-t; enthalpy difference, Δ H s-t; Gibbs free energy difference, Δ G s-t, between the singlet (s) and triplet states (t) of XC 5H 5C, 1X (X = CH, N, P, and As) were computed at B3LYP/6-311++G** and MP2/6-311++G**//B3LYP/6-311++G** levels of theory. The Δ G s-t between the singlet and triplet states of 1 X were changed in the order: 1 P > 1 As > 1 N . 相似文献
19.
Electrides loaded with transition‐metal (TM) nanoparticles have recently attracted attention as emerging materials for catalytic NH 3 synthesis. However, they suffer from disadvantages associated with the growth and aggregation of nanoparticles. TM‐containing intermetallic electrides appear to be promising catalysts with the advantages of both electrides and transition metals in a single phase. LaRuSi is reported here to be an intermetallic electride with superior activity for NH 3 synthesis, and direct evidence is provided supporting its electride‐character‐induced catalytic performance. The discussion is made mainly based on the contrasting synthesis rates over the isostructural compounds LaRuSi, CaRuSi, and LaRu 2Si 2, and the N 2 isotope‐exchange reactions over these compounds. Lattice hydride ions, which can reversibly exchange with anionic electrons, are shown to be indispensable in the promotion of NH x formation. The mechanism derived from the present findings provides new guidelines for NH 3 synthesis. 相似文献
20.
The structural properties, electronic properties, and adsorption abilities for nitrogen monoxide (NO) molecule adsorption on pristine and transition metal (TM = V, Cr, Mn, Nb, Mo, Tc, Ta, W, and Re) doping on B or N site of armchair (5,5) single-walled boron nitride nanotube (BNNT) were investigated using the density functional theory method. The binding energies of TM-doped BNNTs reveal that the Mo atom doping exhibits the strongest binding ability with BNNT. In addition, the NO molecule weakly interacts with the pristine BNNT, whereas it has a strong adsorption ability on TM-doped BNNTs. The increase in the adsorption ability of NO molecule onto the TM-doped BNNTs is due to the geometrical deformation on TM doping site and the charge transfer between TM-doped BNNTs and NO molecule. Moreover, a significant decrease in energy gap of the BNNT after TM doping is expected to be an available strategy for improving its electrical conductivity. These observations suggest that NO adsorption and sensing ability of BNNT could be greatly improved by introducing appropriate TM dopant. Therefore, TM-doped BNNTs may be a useful guidance to be storage and sensing materials for the detection of NO molecule. 相似文献
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