Abstract
In this work, second-generation Car–Parrinello-based mixed quantum-classical mechanics molecular dynamics simulations of small nanoparticles of NbP, NbAs, TaAs, and 1T-TaS2 in water are presented. The first three materials are topological Weyl semimetals, which were recently discovered to be active catalysts in photocatalytic water splitting. The aim of this research was to correlate potential differences in the water structure in the vicinity of the nanoparticle surface with the photocatalytic activity of these materials in light induced proton reduction. The results presented herein allow explaining the catalytic activity of these Weyl semimetals: the most active material, NbP, exhibits a particularly low water coordination near the surface of the nanoparticle, whereas for 1T-TaS2, with the lowest catalytic activity, the water structure at the surface is most ordered. In addition, the photocatalytic activity of several organic and metalorganic photosensitizers in the hydrogen evolution reaction was experimentally investigated with NbP as the proton reduction catalyst. Unexpectedly, the charge of the photosensitizer plays a decisive role for the photocatalytic performance.
Highlights
Catalysis nowadays plays a very important role in almost every field of chemistry
The results presented allow explaining the catalytic activity of these Weyl semimetals: the most active material, NbP, exhibits a low water coordination near the surface of the nanoparticle, whereas for 1T-TaS2, with the lowest catalytic activity, the water structure at the surface is most ordered
To explain the enhanced catalytic reactivity, in this work, we investigate the impact of the water structure around these nanoparticles utilizing second-generation Car–Parrinello-based mixed quantum-classical mechanics (QM/MM) molecular dynamics (MD) simulations in aqueous solution
Summary
Catalysis nowadays plays a very important role in almost every field of chemistry. Owing to its complexity, the understanding of the fundamental processes itself is still a major challenge. An exemplary catalytic process with increasing importance is proton reduction, which employs solar energy to produce molecular hydrogen (H2) with high potential in terms of “green energy.” In this redox process, a metal or a semiconductor is usually employed as a catalyst, which demands a stable supply of itinerant electrons be delivered to the surface. Rajamathi et al have investigated Weyl topological semimetals as catalysts for the catalytic hydrogen evolution reaction (HER).. A fundamental property of Weyl and Dirac semimetals is their high carrier mobility, which arises from the linear bands of the Dirac cone.. A fundamental property of Weyl and Dirac semimetals is their high carrier mobility, which arises from the linear bands of the Dirac cone.12,13 Thanks to their robust and topologically protected surface states, these materials avoid surface contamination, which is the bottleneck in such catalytic transformations.. An essential property of a topological insulator or Weyl semimetal is an energy band inversion, which is known in chemistry as the inert pair effect.. The effect of different organic and metalorganic dyes on the photocatalytic proton reduction activity of NbP, which is the most active monopnictide considered here, is analyzed experimentally
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