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A fascinating pH independent catalyst for hydrogen evolution reaction: Crystalline bimetallic hcp-CoxRh1-x alloy nanofibers driven by thermally induced phase transition from a single phase of CoRh2O4

Title
A fascinating pH independent catalyst for hydrogen evolution reaction: Crystalline bimetallic hcp-CoxRh1-x alloy nanofibers driven by thermally induced phase transition from a single phase of CoRh2O4
Authors
Jin D.Lee Y.Hwa Kim M.Lee C.
Ewha Authors
이종목이영미김명화
SCOPUS Author ID
이종목scopus; 이영미scopus; 김명화scopusscopus
Issue Date
2021
Journal Title
Applied Surface Science
ISSN
0169-4332JCR Link
Citation
Applied Surface Science vol. 553
Keywords
Bimetallic cobalt rhodium alloy (CoxRh1-x)Cobalt rhodium oxide (CoRh2O4)ElectrocatalystHydrogen evolution reactionpH-universal
Publisher
Elsevier B.V.
Indexed
SCIE; SCOPUS WOS scopus
Document Type
Article
Abstract
Two distinct crystalline phases of bimetallic CoxRh1−x alloy nanofibers were synthesized through the thermal H2-reduction of single-phase CoRh2O4 nanofibers that were prepared via calcination preceded by electrospinning. By varying the reduction temperature (T) and retention time (t), it was confirmed that the formation of a fully reduced crystalline metallic alloy required T ≥ 250 °C for t ≥ 2 h. During the reduction process, the single phase of CoRh2O4 was first transformed to an intermediate face centered cubic (fcc) phase where Rh element was principally reduce to Rh(0) and Co element was present as the oxide form. Then, a fully reduced CoxRh1−x alloy was obtained in hexagonal close-packed (hcp) phase. In particular, the hcp structured CoxRh1−x showed a fascinating hydrogen evolution reaction (HER) activity (e.g., the lowest overpotential at 10 mA cm−2 and the smallest Tafel slope) pH independently that was superior to those of commercial Pt and the pure single metal (Co and Rh) nanofibers. CoxRh1−x alloy also showed a robust stability during 10 000-s continuous HER and 1000-repetitive potential sweeps in alkaline (1.0 M NaOH), neutral (1.0 M PBS, pH 7.2) and acidic (0.5 M H2SO4) media. The pH-universal HER activity was ascribed to alloying effect: Co atoms in the alloy interact O atoms in H2O molecules and therefore assist neighboring Rh atoms in adsorbing H atoms readily in alkaline and neutral condition. © 2021
DOI
10.1016/j.apsusc.2021.149568
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자연과학대학 > 화학·나노과학전공 > Journal papers
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