Open accessJournal Article

# Anisotropic Janus SiP2 Monolayer as a Photocatalyst for Water Splitting

04 Mar 2021-Journal of Physical Chemistry Letters (American Chemical Society (ACS))-Vol. 12, Iss: 9, pp 2464-2470
Abstract: The design of materials meeting the rigorous requirements of photocatalytic water splitting is still a challenge. Anisotropic Janus 2D materials exhibit great potential due to outstandingly high photocatalytic efficiency. Unfortunately, these materials are scarce. By means of ab initio swarm-intelligence search calculations, we identify a SiP2 monolayer with Janus structure (i.e., out-of-plane asymmetry). The material turns out to be semiconducting with an indirect band gap of 2.39 eV enclosing the redox potentials of water. Notably, the oxygen and hydrogen evolution half reactions can happen simultaneously at the Si and P atoms, respectively, driven merely by the radiation-induced electrons and holes. The carrier mobility is found to be anisotropic and high, up to 10-4 cm2 V-1 s-1, facilitating fast transport of the photogenerated carriers. The SiP2 monolayer shows remarkably strong optical absorption in the visible-to-ultraviolet range of the solar spectrum, ensuring efficient utilization of the solar energy.

Topics: , Monolayer (55%), Water splitting (55%) ... read more
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Open accessJournal Article
Yu-Liang Liu1, Xin-Xin Jiang2, Bo Li1, Ying Shi1  +2 moreInstitutions (3)
Abstract: Exploring stable photocatalysts with superior optical absorption and high energy conversion efficiency is the key to water splitting. By means of the first-principles calculations, we report a ternary Sn2S2P4 monolayer with excellent stabilities. Remarkably, the material presents an indirect bandgap of 1.77 eV with the band edge perfectly crossing the redox potential of water. Monolayer Sn2S2P4 exhibits noticeable optical absorption and photocurrent density in the visible range and has adequate driving forces to trigger overall water splitting. Anisotropic and high carrier mobility facilitate the fast transport of photogenerated carriers. Moreover, a solar-to-hydrogen efficiency that reaches as high as 17.51% is theoretically predicted, thereby indicating that the Sn2S2P4 monolayer is a promising candidate for overall photocatalytic water splitting.

Topics: Water splitting (60%), , Monolayer (57%) ... read more

2 Citations

Journal Article
H.-Y. He1, Zuoli He1, Q. Shen1Institutions (1)
Abstract: Metallic (1 T) transition metal dichalcogenides illustrate excellent electrical and optical properties and so receive considerable attention in hydrogen evolution electrocatalysis application. Janus structure of this class of materials, an intralayer heterojunction, and its anion-deficiency may have dramatically enhanced hydrogen evolution catalytic activity. This work reports a fast and simple method of assembling the RGO/1 T-MoS2 nanosheet heterostructures. The Janus RGO/1 T-SeMoS nanostructures were also assembled by a hydrothermal substitution reaction in se2− anion aqueous solution, whereas the se-deficient Janus structures were assembled by a hydrothermal reaction in water. Synthesized RGO/1 T-MoS2 and RGO/1 T-MoSe2 nanostructures illustrated an excellent electrocatalytic activity of hydrogen evolution. The Janus and Se-deficient Janus RGO/1 T-SeMoS nanostructures further illustrated dramatically enhanced activity. These novel methods are significant for the assembly of Janus 1 T-transition metal dichalcogenides nanostructures

Topics: Janus (56%)

1 Citations

Journal Article
Meng Tang1, Meng Tang2, Bo Wang1, Bo Wang2  +8 moreInstitutions (5)
Abstract: Taking into account the high conductivity and stability of carbon materials, such as graphene, and the strong polar covalent bonding character of main-group compounds, we explore potential 2D materials in the C-S binary system through first-principles structure search calculations. Herein, a hitherto unknown semiconducting C3S monolayer is identified, consisting of well-known n-biphenyl and S atom linked benzenes, exhibiting an obvious direction-dependent atomic arrangement. Thus, it exhibits anisotropic mechanical properties and carrier mobility. Its electron mobility reaches 2.14 × 104 cm2 V-1 s-1 in the b direction, along which n-biphenyl units are arranged, and is much higher than that in the well-used MoS2 monolayer and black phosphorus. Meanwhile, the C3S monolayer has high optical absorption coefficients (105 cm-1), high thermal and dynamical stabilities, and a moderate ability to split water. All these desirable properties make the C3S monolayer a promising candidate for applications in novel optoelectronic devices.

Topics: Monolayer (65%), Electron mobility (55%), Graphene (52%)

1 Citations

Open accessJournal Article
Liang Xu1, Liang Xu2, Jian Zeng1, Quan Li1  +7 moreInstitutions (3)
Abstract: The first-principles calculations demonstrate that covalently bonded (cb) heterojunction and van der Waals (vdW) heterojunction can coexist in silicene/CeO2 heterojunctions, due to the different stacking patterns. Especially, the cb heterojunction with band gap of 1.97 eV, forms a type-II heterojunction, exhibits good redox performance and has high-effective optical absorption spectra, thus it is a promising photocatalyst for overall water splitting. Besides, for the vdW heterojunction, the Dirac cone of silicene is well kept on CeO2 semiconducting substrate, with a considerable energy gap of 0.43 eV, which can be an ideal material in building silicene-based electronic device. These results may open a new gateway in both of nanoelectronic device and energy conversion for silicene/CeO2 nanocomposites.

Topics: Silicene (68%), Heterojunction (58%), Band gap (51%)

Open accessJournal Article
Abstract: By means of electrocatalytic tests, surface-science techniques and density functional theory, we unveil the physicochemical mechanisms ruling the electrocatalytic activity of recently discovered mitrofanovite (Pt3Te4) mineral. Mitrofanovite represents a very promising electrocatalyst candidate for energy-related applications, with a reduction of costs by 47% compared to pure Pt and superior robustness to CO poisoning. We show that Pt3Te4 is a weak topological metal with the Z 2 invariant, exhibiting electrical conductivity (∼4 × 106 S/m) comparable with pure Pt. In hydrogen evolution reaction (HER), the electrode based on bulk Pt3Te4 shows a very small overpotential of 46 mV at 10 mA cm-2 and a Tafel slope of 36-49 mV dec-1 associated with the Volmer-Heyrovsky mechanism. The outstanding ambient stability of Pt3Te4 also provides durability of the electrode and long-term stability of its efficient catalytic performances.

Topics: Overpotential (54%), Electrocatalyst (54%), Tafel equation (53%)

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65 results found

Journal Article
Georg Kresse1, Jürgen Furthmüller2Institutions (2)
15 Oct 1996-Physical Review B
Abstract: We present an efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrices will be discussed. Our approach is stable, reliable, and minimizes the number of order ${\mathit{N}}_{\mathrm{atoms}}^{3}$ operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special metric'' and a special preconditioning'' optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calculations. It will be shown that the number of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order ${\mathit{N}}_{\mathrm{atoms}}^{2}$ scaling is found for systems containing up to 1000 electrons. If we take into account that the number of k points can be decreased linearly with the system size, the overall scaling can approach ${\mathit{N}}_{\mathrm{atoms}}$. We have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large number of different systems (liquid and amorphous semiconductors, liquid simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable. \textcopyright{} 1996 The American Physical Society.

Topics: DIIS (51%)

64,484 Citations

Open accessJournal Article
Peter E. Blöchl1Institutions (1)
15 Dec 1994-Physical Review B
Abstract: An approach for electronic structure calculations is described that generalizes both the pseudopotential method and the linear augmented-plane-wave (LAPW) method in a natural way. The method allows high-quality first-principles molecular-dynamics calculations to be performed using the original fictitious Lagrangian approach of Car and Parrinello. Like the LAPW method it can be used to treat first-row and transition-metal elements with affordable effort and provides access to the full wave function. The augmentation procedure is generalized in that partial-wave expansions are not determined by the value and the derivative of the envelope function at some muffin-tin radius, but rather by the overlap with localized projector functions. The pseudopotential approach based on generalized separable pseudopotentials can be regained by a simple approximation.

Topics: , Pseudopotential (58%)

48,474 Citations

Open accessJournal Article
Walter Kohn1, L. J. Sham1Institutions (1)
15 Nov 1965-Physical Review
Abstract: From a theory of Hohenberg and Kohn, approximation methods for treating an inhomogeneous system of interacting electrons are developed. These methods are exact for systems of slowly varying or high density. For the ground state, they lead to self-consistent equations analogous to the Hartree and Hartree-Fock equations, respectively. In these equations the exchange and correlation portions of the chemical potential of a uniform electron gas appear as additional effective potentials. (The exchange portion of our effective potential differs from that due to Slater by a factor of $\frac{2}{3}$.) Electronic systems at finite temperatures and in magnetic fields are also treated by similar methods. An appendix deals with a further correction for systems with short-wavelength density oscillations.

Topics: Jellium (56%), Hartree–Fock method (55%), Thomas–Fermi model (55%) ... read more

42,177 Citations

Journal ArticleDOI: 10.1038/238037A0
Akira Fujishima1, Kenichi Honda2Institutions (2)
07 Jul 1972-Nature
Abstract: ALTHOUGH the possibility of water photolysis has been investigated by many workers, a useful method has only now been developed. Because water is transparent to visible light it cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm (ref. 1).

Topics: , Visible spectrum (51%),  ... read more

24,267 Citations

Journal Article
Abstract: Hybrid density functionals are very successful in describing a wide range of molecular properties accurately. In large molecules and solids, however, calculating the exact (Hartree–Fock) exchange is computationally expensive, especially for systems with metallic characteristics. In the present work, we develop a new hybrid density functional based on a screened Coulomb potential for the exchange interaction which circumvents this bottleneck. The results obtained for structural and thermodynamic properties of molecules are comparable in quality to the most widely used hybrid functionals. In addition, we present results of periodic boundary condition calculations for both semiconducting and metallic single wall carbon nanotubes. Using a screened Coulomb potential for Hartree–Fock exchange enables fast and accurate hybrid calculations, even of usually difficult metallic systems. The high accuracy of the new screened Coulomb potential hybrid, combined with its computational advantages, makes it widely applicable to large molecules and periodic systems.