Topological quantum catalyst: Dirac nodal line states and a potential electrocatalyst of hydrogen evolution in the TiSi family

Abstract

Topological nodal line (DNL) semimetals, a closed loop of the inverted bands in its bulk phases, result in the almost flat drumhead-like non-trivial surface states (DNSSs) with an unusually high electronic density near the Fermi level. High catalytic active sites generally associated with high electronic densities around the Fermi level, high carrier mobility and a close-to-zero free energy of the adsorbed state of hydrogen (∆G H* ≈0) are prerequisite to design alternative of precious platinum for catalyzing electrochemical hydrogen production from water. By combining these two aspects, it is natural to consider if the DNLs are a good candidate for the hydrogen evolution reaction (HER) or not because its DNSSs provide a robust platform to activate chemical reactions. Here, through first-principles calculations we reported a new DNL TiSi-type family, exhibiting a closed Dirac nodal line due to the linear band crossings in k y =0 plane. The hydrogen adsorbed state on the surface yields ∆G H* to be almost zero and the topological charge carries participate in HER. The results highlight a new routine to design topological quantum catalyst utilizing the topological DNL-induced surface bands as active sites, rather than edge sites-, vacancy-, dopant-, strain-, or heterostructure-created active sites. Topologically protected surface states in gold-covered Bi 2 Se 3 topological insulators were theoretically suggested to serve as an effective electron path in the case of the CO oxidation [49]. Most recently, TWs (NbP, TaP, NbAs and TaAs) have been considered as excellent candidates of catalysts for hydrogen evolution reaction (HER) [50]. This key concept of TWs as catalysts was pioneered by topological surface states which provide an alternative way to create active sites, rather than by traditionally increasing the active edge sites or vacancies [51][52][53][54][55][56][57][58][59][60]. The possible bottleneck of TWs as electrocatalyst is their lower carrier density around Fermi level (Fig. 1a), because electrostatic screening strength in TWs is much weaker than that in the normal metals (e.g., Pt). DNL semimetal

Topological Engineering of Pt‐Group‐Metal‐Based Chiral Crystals toward High‐Efficiency Hydrogen Evolution Catalysts

“…The observation of the topological order in materials provides an extra reasonable solution for the design of high‐efficiency catalysts. To date, the introduction of the topological order is theoretically and experimentally demonstrated to be effective in tailoring adsorption and catalytic processes in the fields of hydrogen evolution, oxygen evolution, and CO oxidation, etc 14–20. The situation looks perfect!…”

Phase‐Engineered Weyl Semi‐Metallic MoxW1‐xTe2 Nanosheets as a Highly Efficient Electrocatalyst for Dye‐Sensitized Solar Cells

“…Similarly, the charge mobility of μ = 385.47 ± 10.9 cm 2 V −1 s −1 in T d ‐Mo 0.29 W 0.72 Te 1.99 is also significantly higher than μ = (276.11 ± 7.8 cm 2 V −1 s −1 ) in the counterpart of T d ‐ & 2H‐ Mo 0.32 W 0.67 Te 2.01 . It is important to note that the high carrier density and mobility in the CE of DSSC are essential for the electrocatalytic redox reactions, where a dense flow of migrating charge carriers can trigger rapid charge transfers at the CE/electrolyte interface to enhance the reaction kinetics . As the electrochemical application illustrated in Figure e, various CVD‐grown Mo x W 1‐x Te 2 nanocrystals were employed as different CEs in DSSC to compare their electrocatalytic activities.…”

“…A recent report reveals the potential of employing TWS in catalysis, where the key concept behind this catalysis mechanism arises from the topologically protected surface states of TWS to serve as an effective charge transport platform. These topological surface states provide an alternative catalytic mechanism, in contrast to the traditional approach of increasing active edge sites or vacancies . In particular, the type‐II TWS have an inverted band structure with broken inversion symmetry, leading to the existence of topological surface states, which are stable against defects, impurities, and other surface modifications .…”

Strain-Tuned Nodal Ring in Two-Dimensional Zn3C6S6 Monolayers

“…It can be seen from the overall charge density map that the charge densities of (a), (f), (g), and Further, it is assumed that if nodal rings do exist, it should be possible to observe more intersections throughout the BZ in terms of symmetry effects [27]. Scilicet, a complete elliptic Dirac nodal line (DNL) [28] should exist near point Γ in the Brillouin belt. In order to verify this conjecture, we take Γ as the initial point and draw a number of surrounding Dirac cones appear on every ray we calculate, so the appearance of the Dirac cone near point K is an inevitable event.…”