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06:32
A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions
Published on: August 17, 2016
Transition metal sulfide hydrogen evolution catalysts for hydrobromic acid electrolysis
Anna Ivanovskaya1, Nirala Singh, Ru-Fen Liu
1Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States. annai@seamedical.com
Langmuir : the ACS Journal of Surfaces and Colloids
|December 5, 2012
Summary
Cobalt and nickel-substituted ruthenium disulfide (RuS2) show promise as electrocatalysts for the hydrogen evolution reaction (HER) in hydrobromic acid (HBr). Optimized Co-Ru disulfide exhibits high HER activity and stability, comparable to platinum.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- Developing efficient electrocatalysts for the hydrogen evolution reaction (HER) is crucial for renewable energy technologies.
- Aqueous hydrobromic acid (HBr) is a challenging medium for HER electrocatalysis due to its corrosive nature.
Purpose of the Study:
- To synthesize and screen mixed metal sulfides for HER activity and stability in aqueous HBr.
- To identify and optimize specific compositions of cobalt- and nickel-substituted RuS2 as potential HER electrocatalysts.
Main Methods:
- High-throughput screening (HTS) of mixed metal sulfides (W, Fe, Mo, Ni, Ru).
- Optimization of promising Co- and Ni-substituted RuS2 compositions (Co(0.4)Ru(0.6)S(2) and Ni(0.6)Ru(0.4)S(2)).
- Electrochemical characterization, structural analysis (X-ray diffraction), and density functional theory (DFT) calculations.
Main Results:
- Co- and Ni-substituted RuS2 were identified as active HER electrocatalysts.
- Co(0.4)Ru(0.6)S(2) demonstrated HER activity comparable to Pt and commercial RhxSy in HBr.
- Co-substituted RuS2 formed a homogeneous solid solution with a pyrite structure, showing initial Co loss followed by stable HER activity.
- DFT calculations indicated that S(2)(2-) sites are key for HER, with Co influencing hydrogen binding energy.
Conclusions:
- Co(0.4)Ru(0.6)S(2) is a promising electrocatalyst for HER in HBr, offering high activity and stability.
- While RuS2-based catalysts show good HER activity, their slow hydrogen oxidation limits their use in regenerative HBr cells.
- Rhodium sulfide remains the most suitable tested material for regenerative HBr cells due to its superior stability.
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