Electrochemical water splitting could be useful for the production of hydrogen using renewable energy. However, the oxygen evolution reaction (OER), one half-reaction in electrochemical water splitting, suffers from sluggish kinetics. High-performance electrocatalysts for this reaction are, thus, needed. Nanomaterials based on non-noble transition metals such as cobalt could be promising candidates for this. Layered cobalt hydroxide (Co(OH)2), for example, could be useful for the OER. However, it has been challenging to tune the thickness of Co(OH)2 nanomaterials.
Leigang Li, Lingzheng Bu, Xiaoqing Huang, Xiamen University, China, and colleagues have developed a ligand-assisted liquid-phase strategy to synthesize a series of Co(OH)2-CoO hybrid nanosheets with tunable thicknesses of 2–6 nm. The team used different alkylamines as ligands (i.e., ethylamine, propylamine, and butylamine) in a solvothermal synthesis of Co(OH)2-CoO nanosheets from cobalt acetate. The ligand controls the thickness of the resulting nanosheets by confining growth: Nanosheets with thicknesses of 2 nm, 4 nm, and 6 m were synthesized using butylamine, propylamine, and ethylamine, respectively.
The team found that the thinnest nanosheets with a thickness of 2 nm showed the highest OER activity and good stability. They propose that this is due to, e.g., a larger number of oxygen vacancies and active sites and faster electron transport than in thicker nanosheets. According to the researchers, the work provides an efficient method for the controlled synthesis of layered hydroxide/oxide nanosheets with tunable thickness.
- Alkylamine-Confined Thickness-Tunable Synthesis of Co(OH)2-CoO Nanosheets toward Oxygen Evolution Catalysis,
Chuansheng He, Linlin Yang, Xiaohui Peng, Shangheng Liu, Jia Wang, Chengyuan Dong, Delin Du, Leigang Li, Lingzheng Bu, Xiaoqing Huang,
ACS Nano 2023.