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Journal ArticleDOI: 10.1039/D0CY02192J

Highly stable Mo-doped Fe2P and Fe3P monolayers as low-onset-potential electrocatalysts for nitrogen fixation

02 Mar 2021-Catalysis Science & Technology (The Royal Society of Chemistry)-Vol. 11, Iss: 4, pp 1419-1429
Abstract: Ammonia (NH3) is an essential ingredient for fertilizer production and a carbon-free energy carrier for engineering applications. Searching for novel electrocatalysts with low onset potential, high selectivity and excellent stability is still one of the most attractive and challenging topics. Here, based on the conductor-like screening model and first-principles calculations, we systematically investigated nitrogen reduction reaction (NRR) pathways occurring on iron-based phosphide monolayers. It can be found that Mo-doped Fe2P and Fe3P monolayers can efficiently promote the NRR with onset potentials of −0.30 V and −0.17 V, respectively, especially for the Mo-doped Fe3P monolayer, which has the lowest onset potential to date. Electronic analysis shows that the Mo atom doping can significantly enhance the degree of matching between the d-orbitals of transition metal atoms and the p-orbitals of the N2 molecule, contributing to the activation of dinitrogen. Furthermore, Mo and Fe atoms provide bimetallic active sites, helping to avoid the linear relationship during the NRR pathway. Besides, the competing hydrogen evolution reaction (HER) is suppressed because of larger onset potentials and ab initio molecular dynamics (AIMD) simulations were performed to identify the high stabilities of the Mo-doped monolayers. This work offers useful insights into the design of high-performance electrocatalysts for the NRR and provides guidance for future experimental and theoretical investigations.

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5 results found

Journal ArticleDOI: 10.1021/ACSAMI.0C21429
Jie Wu1, Jia-Hui Li1, Yang-Xin Yu1Institutions (1)
Abstract: Conversion of dinitrogen (N2) molecules into ammonia through electrochemical methods is a promising alternative to the traditional Haber-Bosch process. However, searching for an eligible electrocatalyst with high stability, low-onset potential, and superior selectivity is still one of the most challenging and attractive topics for the electrochemical N2 reduction reaction (NRR). Here, by means of first-principles calculations and the conductor-like screening model, four comprehensive criteria were proposed to screen out eligible NRR electrocatalysts from 29 atomic transition metals embedded on the defective boron phosphide (BP) monolayer with B-monovacancy (M/BP single-atom catalysts, SAC, M = Sc-Zn, Y-Cd, and Hf-Hg). Consequently, the Nb/BP and W/BP SACs are identified as the promising candidates, on which the N2 molecule can only be activated through the enzymatic pathway with the onset potentials of -0.25 and -0.19 V, and selectivities of 90.5 and 100%, respectively. It is worth noting that the W/BP SAC has the lowest overpotential among the 29 systems investigated. The electronic properties were also calculated in detail to analyze the activity origin. Importantly, the Nb/BP and W/BP SACs possess high thermal stabilities due to that their structures can be retained very well up to 1000 and 700 K, respectively. This work not only provides an efficient and reliable method to screen eligible NRR electrocatalysts but also paves a new way for advancing sustainable ammonia synthesis.

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Topics: Electrocatalyst (50%)

8 Citations

Journal ArticleDOI: 10.1021/ACS.JPCLETT.1C00855
Jie Wu1, Jia-Hui Li1, Yang-Xin Yu1Institutions (1)
Abstract: Electrocatalytic conversion of nitrate (NO3-) into ammonia can not only eliminate harmful pollutant but also provide a green method for a low-temperature ammonia synthesis. The electrochemical NO3- reduction reactions (NO3RRs) of a series of transition-metal-doped hexagonal boron phosphide (h-BP) monolayers were comprehensively evaluated using density functional theory. The V-doped h-BP monolayer was found to stand near the top of the volcano plot with the limiting potential of -0.22 V versus a reversible hydrogen electrode, exhibiting the lowest overpotential among the investigated systems in this work. Besides, the competing hydrogen evolution reaction is significantly suppressed due to the weak adsorption of the H atom. Importantly, the structure of the V-doped h-BP monolayer can be retained very well until 900 K, illustrating the initial indication of high thermal stability and great promise for synthesis. This study not only offers an eligible NO3RR electrocatalyst but also provides an atomic understanding of the behind mechanisms of the NO3RR process.

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Topics: Reversible hydrogen electrode (58%), Electrocatalyst (57%), Overpotential (56%) ... show more

3 Citations

Journal ArticleDOI: 10.1039/D1TA03420K
Zheng Shu1, Yongqing Cai1Institutions (1)
Abstract: A nitrogen reduction reaction (NRR) which converts nitrogen (N2) to ammonia (NH3) normally requires harsh conditions to break the bound nitrogen bond. Herein, via first-principles calculation it is revealed that a superior NRR catalytic activity could be obtained by anchoring an atomic catalyst above the phosphorene-like puckered surface of germanium selenide (GeSe). By examining the single- and double-atoms (B, Fe, Mo Ru and W) decorated on GeSe, it is found that its rippled structure allows an intimate contact between the deposited species and the GeSe which significantly promotes the states hybridization. Out of all the various atomic catalysts, it is found that the Ru dimer decorated GeSe monolayer (Ru2@GeSe) has superior catalytic activity for the N2 fixation and reduction. By examining the three NRR pathways (distal, alternating and enzymatic), it was found that the distal and enzymatic pathways are both thermodynamically favorable with the maximum Gibbs free energy change (ΔGMAX) of 0.25 and 0.26 eV, respectively. Such a superior activity could be attributed to the Ru dimer filtering the states of GeSe which leads to the effective activation of the adsorbed N2 bond. As an efficient near-infrared absorber of GeSe, the Ru mediated hybridization of the GeSe–Ru–N2 complex enables an in-gap state which further broadens the absorption window, rendering for a broadband solar absorption and possible photocatalysis.

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Topics: Germanium selenide (57%)

1 Citations

Journal ArticleDOI: 10.1016/J.APSUSC.2021.150567
Jie Wu1, Jing Wen1, Jing Wen2, Yang-Xin Yu1Institutions (2)
Abstract: Direct methanol fuel cell (DMFC) running on hydrogen is an attractive alternative power source for a wide range of applications. Importantly, the required hydrogen can be in situ released from the stable liquid, which ensures its safe transformation and storage. However, the catalyst in DMFC is usually poisoned by the generated CO species, thus it is challenging to find an efficient and durable catalyst for practical applications. Here, the mechanism of methanol oxidation reaction (MOR) on the Mo2P monolayer is first studied using density functional theory. Compared with the initial C–H and C–O bond scissions, the initial O–H bond scission is found to be the most favorable. The reason is systematically analyzed based on steric effect, activation Gibbs free energy (Gact) decomposition and the Bronsted − Evans − Polanyi (BEP) relationships. The further dehydrogenation of CH2OH via the O–H bond scission has a significantly lower Gact than that of CH3O, thus the methanol decomposition on the Mo2P monolayer may proceed via two competitive pathways, i.e., CH 3 OH → CH 3 O → CH 2 O → CHO → CO and CH 3 OH → CH 2 OH → CH 2 O → CHO → CO . Then, through overcoming a relatively low barrier, the generated CO species can be combined with hydroxyl group from water dissociation on the Mo2P monolayer to produce formic acid, which can be easily desorbed from the catalyst surface to avoid the block of active sites. This study provides a better understanding of the MOR mechanism and paves the way for further advancing the catalyst in DMFCs.

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Topics: Direct methanol fuel cell (56%), Catalysis (54%), Methanol (52%) ... show more

61 results found

Journal ArticleDOI: 10.1103/PHYSREVLETT.77.3865
Abstract: Generalized gradient approximations (GGA’s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. [S0031-9007(96)01479-2] PACS numbers: 71.15.Mb, 71.45.Gm Kohn-Sham density functional theory [1,2] is widely used for self-consistent-field electronic structure calculations of the ground-state properties of atoms, molecules, and solids. In this theory, only the exchange-correlation energy EXC › EX 1 EC as a functional of the electron spin densities n"srd and n#srd must be approximated. The most popular functionals have a form appropriate for slowly varying densities: the local spin density (LSD) approximation Z d 3 rn e unif

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117,932 Citations

Journal ArticleDOI: 10.1002/JCC.20495
Stefan Grimme1Institutions (1)
Abstract: A new density functional (DF) of the generalized gradient approximation (GGA) type for general chemistry applications termed B97-D is proposed. It is based on Becke's power-series ansatz from 1997 and is explicitly parameterized by including damped atom-pairwise dispersion corrections of the form C(6) x R(-6). A general computational scheme for the parameters used in this correction has been established and parameters for elements up to xenon and a scaling factor for the dispersion part for several common density functionals (BLYP, PBE, TPSS, B3LYP) are reported. The new functional is tested in comparison with other GGAs and the B3LYP hybrid functional on standard thermochemical benchmark sets, for 40 noncovalently bound complexes, including large stacked aromatic molecules and group II element clusters, and for the computation of molecular geometries. Further cross-validation tests were performed for organometallic reactions and other difficult problems for standard functionals. In summary, it is found that B97-D belongs to one of the most accurate general purpose GGAs, reaching, for example for the G97/2 set of heat of formations, a mean absolute deviation of only 3.8 kcal mol(-1). The performance for noncovalently bound systems including many pure van der Waals complexes is exceptionally good, reaching on the average CCSD(T) accuracy. The basic strategy in the development to restrict the density functional description to shorter electron correlation lengths scales and to describe situations with medium to large interatomic distances by damped C(6) x R(-6) terms seems to be very successful, as demonstrated for some notoriously difficult reactions. As an example, for the isomerization of larger branched to linear alkanes, B97-D is the only DF available that yields the right sign for the energy difference. From a practical point of view, the new functional seems to be quite robust and it is thus suggested as an efficient and accurate quantum chemical method for large systems where dispersion forces are of general importance.

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18,839 Citations

Journal ArticleDOI: 10.1063/1.1316015
Abstract: Recent extensions of the DMol3 local orbital density functional method for band structure calculations of insulating and metallic solids are described. Furthermore the method for calculating semilocal pseudopotential matrix elements and basis functions are detailed together with other unpublished parts of the methodology pertaining to gradient functionals and local orbital basis sets. The method is applied to calculations of the enthalpy of formation of a set of molecules and solids. We find that the present numerical localized basis sets yield improved results as compared to previous results for the same functionals. Enthalpies for the formation of H, N, O, F, Cl, and C, Si, S atoms from the thermodynamic reference states are calculated at the same level of theory. It is found that the performance in predicting molecular enthalpies of formation is markedly improved for the Perdew–Burke–Ernzerhof [Phys. Rev. Lett. 77, 3865 (1996)] functional.

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Topics: Density functional theory (57%), DMol3 (55%), Pseudopotential (53%) ... show more

7,255 Citations

Journal ArticleDOI: 10.1039/P29930000799
Abstract: Starting from the screening in conductors, an algorithm for the accurate calculation of dielectric screening effects in solvents is presented, which leads to rather simple explicit expressions for the screening energy and its analytic gradient with respect to the solute coordinates. Thus geometry optimization of a solute within a realistic dielectric continuum model becomes practicable for the first time. The algorithm is suited for molecular mechanics as well as for any molecular orbital algorithm. The implementation into MOPAC and some example applications are reported.

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7,100 Citations

Journal ArticleDOI: 10.1021/JP047349J
Abstract: We present a method for calculating the stability of reaction intermediates of electrochemical processes on the basis of electronic structure calculations. We used that method in combination with detailed density functional calculations to develop a detailed description of the free-energy landscape of the electrochemical oxygen reduction reaction over Pt(111) as a function of applied bias. This allowed us to identify the origin of the overpotential found for this reaction. Adsorbed oxygen and hydroxyl are found to be very stable intermediates at potentials close to equilibrium, and the calculated rate constant for the activated proton/electron transfer to adsorbed oxygen or hydroxyl can account quantitatively for the observed kinetics. On the basis of a database of calculated oxygen and hydroxyl adsorption energies, the trends in the oxygen reduction rate for a large number of different transition and noble metals can be accounted for. Alternative reaction mechanisms involving proton/electron transfer to ...

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Topics: Overpotential (59%), Reaction rate constant (57%), Oxygen (53%) ... show more

5,473 Citations