Developing high‐performance electrocatalysts for CO2 reduction reaction (CO2RR) is vital in achieving a carbon‐neutral society by converting CO2 into valuable chemicals. CO2RR electrocatalyst with ...lower overpotential, higher selectivity and wider working potential range is urgently desired, but it is still challenging to realize these factors simultaneously. Here, high‐performance bismuthene‐based electrocatalysts were synthesized by reducing bismuth precursors like BiCl3, BiBr3, and BiI3 in liquid phases. Especially, bismuthene‐I derived from BiI3 showed a nanosheet morphology (around four‐layer) with significantly enhanced (110) surfaces. It enabled an ultrawide potential window (0.7 V) for high formate selectivity (>90%) in a H‐type cell and achieved an ultralow potential (−0.46 V vs. reversible hydrogen electrode) to attain a current density of 200 mA cm−2 in a gas‐diffusion flow cell. The prominent long‐term operational capability of bismuthene‐I was demonstrated in both H‐type and gas‐diffusion cells. Density functional theory calculations revealed that bismuthene‐I possessed abundant topological Bi(110) surfaces states that can reduce the CO2RR overpotential, suppress the competitive hydrogen evolution reaction, and facilitate electron donation during CO2 electrocatalysis. The bismuthene‐I realized low overpotential, high selectivity and wide working potential range simultaneously for electrochemical CO2RR. This work unfolds the broader plausibility of facilely reducing precursors for the scalable fabrication of high‐performing CO2RR electrocatalysts.
Abstract Developing high‐performance electrocatalysts for CO 2 reduction reaction (CO 2 RR) is vital in achieving a carbon‐neutral society by converting CO 2 into valuable chemicals. CO 2 RR ...electrocatalyst with lower overpotential, higher selectivity and wider working potential range is urgently desired, but it is still challenging to realize these factors simultaneously. Here, high‐performance bismuthene‐based electrocatalysts were synthesized by reducing bismuth precursors like BiCl 3 , BiBr 3 , and BiI 3 in liquid phases. Especially, bismuthene‐I derived from BiI 3 showed a nanosheet morphology (around four‐layer) with significantly enhanced (110) surfaces. It enabled an ultrawide potential window (0.7 V) for high formate selectivity (>90%) in a H‐type cell and achieved an ultralow potential (−0.46 V vs. reversible hydrogen electrode) to attain a current density of 200 mA cm −2 in a gas‐diffusion flow cell. The prominent long‐term operational capability of bismuthene‐I was demonstrated in both H‐type and gas‐diffusion cells. Density functional theory calculations revealed that bismuthene‐I possessed abundant topological Bi(110) surfaces states that can reduce the CO 2 RR overpotential, suppress the competitive hydrogen evolution reaction, and facilitate electron donation during CO 2 electrocatalysis. The bismuthene‐I realized low overpotential, high selectivity and wide working potential range simultaneously for electrochemical CO 2 RR. This work unfolds the broader plausibility of facilely reducing precursors for the scalable fabrication of high‐performing CO 2 RR electrocatalysts.
Structural, electronic, magnetic, and optical properties of rare earth (RE) metal element doped GaN monolayers are investigated using density functional theory, where RE = Nd, Sm, Eu, Gd, and Er. The ...introduction of RE atoms causes structural deformation of the GaN monolayer. The induced local magnetic moments are observed to be 4.00, 6.00, 7.00, 8.00, and 2.00 μB in Nd, Sm, Eu, Gd, and Er adsorbed GaN monolayers, respectively, while the values are 3.00, 5.00, 6.00, 7.00, and 3.00 μB in the substitution of Ga atoms. When Nd, Gd and Er adsorbed in GaN monolayer Fermi levels are shifted to the conduction band leading to metallicity, while in the case of Sm and Eu adsorption impurity states are found near the Fermi level. On the contrary, Eu, Gd and Er substitution of Ga atoms leads to the Fermi energy level being shifted below the VBM. In the Nd and Eu substitution system, the f-state is found near the Fermi level and the Nd-f state crosses the Fermi level. Optical absorption, transmission and refraction coefficients show that the addition of RE atoms can significantly enhance the prospects of GAN monolayers in visible as well as infrared applications. This research provides an outlook for the development of GaN monolayer-based optoelectronic as well as spintronics devices.
•In comparison to GaN bulk materials, 2D GaN materials exhibit superior electronic, magnetic and optical properties.•Both substitution and adsorption doping methods were considered to study their electronic, magnetic and optical properties.•The f-state electrons (Nd, Sm, Eu, Gd, and Er) of rare earth elements exhibit large local magnetic moments.•RE atoms can significantly enhance the prospects of GAN monolayers in visible as well as infrared applications.
2D material‐based heterostructures are constructed by stacking or spicing individual 2D layers to create an interface between them, which have exotic properties. Here, a new strategy for the in situ ...growth of large numbers of 2D heterostructures on the centimeter‐scale substrate is developed. In the method, large numbers of 2D MoS2, MoO2, or their heterostructures of MoO2/MoS2 are controllably grown in the same setup by simply tuning the gap distance between metal precursor and growth substrate, which changes the concentration of metal precursors feed. A lateral force microscope is used first to identify the locations of each material in the heterostructures, which have MoO2 on the top of MoS2. Noteworthy, the creation of a clean interface between atomic thin MoO2 (metallic) and MoS2 (semiconducting) results in a different electronic structure compared with pure MoO2 and MoS2. Theoretical calculations show that the charge redistribution at such an interface results in an improved HER performance on the MoO2/MoS2 heterostructures, showing an overpotential of 60 mV at 10 mA cm−2 and a Tafel slope of 47 mV dec−1. This work reports a new strategy for the in situ growth of heterostructures on large‐scale substrates and provides platforms to exploit their applications.
Here, in situ growth of 2D MoO2/MoS2 heterostructures on the centimeter‐scale substrate is shown. Noteworthy, the creation of a clean interface between atomic thin MoO2 (metallic) and MoS2 (semiconducting) results in a different electronic structure, which shows an improved HER performance with an overpotential of 60 mV at 10 mA cm−2 and a Tafel slope of 47 mV dec−1.
The electronic structure and room temperature ferromagnetism of wurtzite Cu–Gd co-doped GaN nanowires have been investigated by means of the first-principles calculations within the density ...functional theory, including the on-site Coulomb energy U. The magnetic coupling between Gd atoms in the Gd-doped GaN nanowire is paramagnetic instead of ferromagnetic (FM) as in the bulk structure. After replacing Ga with Cu atom we find a stable FM coupling between Gd magnetic moments in this p-type system. p–d coupling between Cu-3d and N-2p states pushes N-2p states up to Fermi level due to the existence of hole states introduced by Cu dopants. While the p–d coupling between host N-2p and Gd-5d states near Fermi level stabilizes a FM phase of Gd magnetic moments. Furthermore, we get a FM state above room temperature by increasing the holes concentration.
•The magnetic and electronic properties of Cu–Gd co-doped GaN nanowires have been studied by first principles calculation.•Gd doped GaN nanowires are paramagnetic while Cu–Gd co-doped GaN nanowires are ferromagnetic.•The mechanism of this ferromagnetic is p–d coupling.•Room temperature ferromagnetism in Cu–Gd co-doped system can be obtained by increasing holes concentration.
Pyridinic nitrogen has been recognized as the primary active site in nitrogen-doped carbon electrocatalysts for the oxygen reduction reaction (ORR), which is a critical process in many renewable ...energy devices. However, the preparation of nitrogen-doped carbon catalysts comprised of exclusively pyridinic nitrogen remains challenging, as well as understanding the precise ORR mechanisms on the catalyst. Herein, a novel process is developed using pyridyne reactive intermediates to functionalize carbon nanotubes (CNTs) exclusively with pyridine rings for ORR electrocatalysis. The relationship between the structure and ORR performance of the prepared materials is studied in combination with density functional theory calculations to probe the ORR mechanism on the catalyst. Pyridinic nitrogen can contribute to a more efficient 4-electron reaction pathway, while high level of pyridyne functionalization result in negative structural effects, such as poor electrical conductivity, reduced surface area, and small pore diameters, that suppressed the ORR performance. This study provides insights into pyridine-doped CNTs-functionalized for the first time via pyridyne intermediates-as applied in the ORR and is expected to serve as valuable inspiration in designing high-performance electrocatalysts for energy applications.
Abstract
2D material‐based heterostructures are constructed by stacking or spicing individual 2D layers to create an interface between them, which have exotic properties. Here, a new strategy for the ...in situ growth of large numbers of 2D heterostructures on the centimeter‐scale substrate is developed. In the method, large numbers of 2D MoS
2
, MoO
2
, or their heterostructures of MoO
2
/MoS
2
are controllably grown in the same setup by simply tuning the gap distance between metal precursor and growth substrate, which changes the concentration of metal precursors feed. A lateral force microscope is used first to identify the locations of each material in the heterostructures, which have MoO
2
on the top of MoS
2
. Noteworthy, the creation of a clean interface between atomic thin MoO
2
(metallic) and MoS
2
(semiconducting) results in a different electronic structure compared with pure MoO
2
and MoS
2
. Theoretical calculations show that the charge redistribution at such an interface results in an improved HER performance on the MoO
2
/MoS
2
heterostructures, showing an overpotential of 60 mV at 10 mA cm
−2
and a Tafel slope of 47 mV dec
−1
. This work reports a new strategy for the in situ growth of heterostructures on large‐scale substrates and provides platforms to exploit their applications.
Abstract
Bismuth (Bi) is a topological crystalline insulator (TCI), which has gapless topological surface states (TSSs) protected by a specific crystalline symmetry that strongly depends on the ...facet. Bi is also a promising electrochemical CO
2
reduction reaction (ECO
2
RR) electrocatalyst for formate production. In this study, single‐crystalline Bi rhombic dodecahedrons (RDs) exposed with (104) and (110) facets are developed. The Bi RDs demonstrate a very low overpotential and high selectivity for formate production (Faradic efficiency >92.2%) in a wide partial current density range from 9.8 to 290.1 mA cm
−2
, leading to a remarkably high full‐cell energy efficiency (69.5%) for ECO
2
RR. The significantly reduced overpotential is caused by the enhanced *OCHO adsorption on the Bi RDs. The high selectivity of formate can be ascribed to the TSSs and the trivial surface states opening small gaps in the bulk gap on Bi RDs, which strengthens and stabilizes the preferentially adsorbed *OCHO and mitigates the competing adsorption of *H during ECO
2
RR. This study describes a promising application of Bi RDs for high‐rate formate production and high‐efficiency energy storage of intermittent renewable electricity. Optimizing the geometry of TCIs is also proposed as an effective strategy to tune the TSSs of topological catalysts.
The edge sites of Cu nanosheets with a coordination number around 5 facilitate the formation of *CHO and promote CC coupling reaction, thus leading to the high selectivity for C2H4 formation by ...electrochemical CO2 reduction.
Display omitted
The conversion of CO2 into value-added chemicals coupled with the storage of intermittent renewable electricity is attractive. CuO nanosheets with an average size and thickness of ∼ 30 and ∼ 20 nm have been developed, which are in situ reduced into Cu nanosheets during electrochemical CO2 reduction reaction (ECO2RR). The derived Cu nanosheets demonstrate much higher selectivity for C2H4 production than commercial CuO derived Cu powder, with an optimum Faradaic efficiency of 56.2% and a partial current density of C2H4 as large as 171.0 mA cm−2 in a gas diffusion flow cell. The operando attenuated total reflectance-Fourier transform infrared spectra measurements and density functional theory simulations illustrate that the high activity and selectivity of Cu nanosheets originate from the edge sites on Cu nanosheets with a coordinate number around 5 (4–6), which facilitates the formation of *CHO rather than *COH intermediate, meanwhile boosting the C C coupling reaction of *CO and *CHO intermediates, which are the critical steps for C2H4 formation.
PDF
