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Title: ZrB 2-HfB 2 solid solutions as electrode materials for hydrogen reaction in acidic and basic solutions

Spark plasma sintered transition metal diborides such as HfB 2, ZrB 2 and their solid solutions were investigated as electrode materials for electrochemical hydrogen evolutions reactions (HER) in 1 M H 2SO 4 and 1 M NaOH electrolytes. HfB 2 and ZrB 2 formed complete solid solutions when mixed in 1:1, 1:4, and 4:1 ratios and they were stable in both electrolytes. The HER kinetics of the diborides were slower in the basic solution than in the acidic solutions. The Tafel slopes in 1 M H 2SO 4 were in the range of 0.15 - 0.18 V/decade except for pure HfB 2 which showed a Tafel slope of 0.38 V/decade. In 1 M NaOH the Tafel slopes were in the range of 0.12 - 0.27 V/decade. The composition of Hf xZr 1-xB 2 solid solutions with x = 0.2 - 0.8, influenced the exchange current densities, overpotentials and Tafel slopes of the HER. As a result, the EIS data were fitted with a porous film equivalent circuit model in order to better understand the HER behavior. In addition, modeling calculations, using density functional theory approach, were carried out to estimate the density of states and band structure of the boridemore » solid solutions.« less
Authors:
 [1] ;  [1] ;  [1]
  1. Univ. of Idaho, Moscow, ID (United States)
Publication Date:
Grant/Contract Number:
FE0022988
Type:
Accepted Manuscript
Journal Name:
Materials Letters
Additional Journal Information:
Journal Name: Materials Letters; Journal ID: ISSN 0167-577X
Publisher:
Elsevier
Research Org:
Univ. of Idaho, Moscow, ID (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 25 ENERGY STORAGE; electroceramics; energy storage and conversion; solar energy materials; borides; ceramic composites
OSTI Identifier:
1331595
Alternate Identifier(s):
OSTI ID: 1411449