Persistence and Evolution of Materials Features During Catalysis Using Topological and Trivial Polymorphs of MoTe₂

Abstract

Topological materials have high carrier mobilities that can be maintained in the presence of crystal structure defects, which is useful for catalysis. Topological materials have been shown to be active catalysts, but it remains unclear if topology persists during catalysis. We studied the physical and chemical evolution of MoTe 2 during photo-and electrocatalytic hydrogen production. This material offers a unique opportunity to directly compare a trivial semiconductor, 2H-MoTe 2 , with a topological insulator, 1T'-MoTe 2 , with comparable compositions, crystal structures, and surface roughnesses. We observed no major bulk changes in the materials after catalysis. The surfaces of the catalysts were significantly roughened and oxidized, but the carrier mobility of the topological phase remained high. These results suggest that topology persists during, and may be advantageous for, catalysis, and provide rationale for considering topology in the search for water-splitting catalysts.

Formation and Transformation of Cu2–xSe1–yTey Nanoparticles Synthesized by Tellurium Anion Exchange of Copper Selenide

“…36 However, for the sample analyzed after storage in air, the primary Te 3d 5/2 peak shifted to 575.8 eV, which is consistent with that of Te 4+ in TeO 2 and therefore indicates surface oxidation. 37 The XPS results therefore support the formation of a TeO 2 shell around the tellurium-exchanged particles over time as the sample is stored. There are two important consequences of this observation.…”

“…The peak at 568.6 eV corresponds to the Cu LMM Auger peak . However, for the sample analyzed after storage in air, the primary Te 3d 5/2 peak shifted to 575.8 eV, which is consistent with that of Te 4+ in TeO 2 and therefore indicates surface oxidation …”