Abstract

Phase-pure samples and single crystals of the rare-earth oxyselenides RE4Ga2Se7O2 (RE = Pr, Nd) were prepared by reactions at 950 °C. They adopt a new structure type (orthorhombic, space group Pnma, a = 11.721(2)-11.683(2) Å, b = 3.9882(7)-3.9667(7) Å, c = 29.644(5)-29.581(5) Å, Z = 4) consisting of RESe6 trigonal prisms, GaSe4 tetrahedra, and GaSe5 trigonal bipyramids linked to form corrugated layers between which strips of edge-sharing RE4O tetrahedra are inserted. The bonding character is mostly ionic within RE-O and RE-Se blocks but mostly covalent with Ga-Se blocks, as supported by electronic structure calculations. Both compounds show a nearly direct optical band gap of 1.7 eV. Their Seebeck coefficients and electrical conductivities are predicted to be similar to other oxychalcogenides, with the thermoelectric power factors being improved by n-doping. They exhibit high electrocatalytic performance for the oxygen evolution reaction, with the Pr member demonstrating superior activity, as characterized by a low overpotential of 257 mV (at a current density of 10 mA cm-2), a high mass activity of 70.1 A g-1, and a turnover frequency of 0.0234 s-1 in 1 M KOH electrolyte.

Department(s)

Chemistry

Comments

National Science Foundation, Grant CAS-2155175

International Standard Serial Number (ISSN)

1520-5002; 0897-4756

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Chemical Society, All rights reserved.

Publication Date

23 Jan 2024

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