Promoting the hydrogen evolution reaction through oxygen vacancies and phase transformation engineering on layered double hydroxide nanosheets

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 8; no. 5; pp. 249 - 2497
• Main Authors: Liu, Shujie, Zhu, Jie, Sun, Mao, Ma, Zhixue, Hu, Kan, Nakajima, Tomohiko, Liu, Xianhu, Schmuki, Patrik, Wang, Lei
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2020
• Subjects: Cobalt ferrites; Electrical conductivity; Electrical resistivity; Electrocatalysts; Electronic structure; Engineering; Etching; Evolution; Hydrogen evolution reactions; Hydroxides; Iron compounds; Metal foams; Nanosheets; Nickel; Nickel compounds; Oxygen; Oxygen evolution reactions; Phase transitions; Plasma etching; Water splitting
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta12768b

In electrocatalysis, layered double hydroxide (LDH) materials have attracted considerable interest in promoting the oxygen evolution reaction (OER). For the hydrogen evolution reaction (HER), these materials show a poor electrocatalytic activity. In this work, we take CoFe LDH grown on nickel foam as a model system, and for the first time we treat CoFe LDH under plasma etching conditions, which results in a highly active HER electrocatalyst in alkaline media. Massive defects and amorphous phase formation occur during plasma etching. More importantly, phase transformation of CoFe LDH into CoFe 2 O 4 takes place. Additional introduction of Ce leads to more active sites and improved electrical conductivity, which provide an overpotential of 73 mV at a current density of 10 mA cm −2 for V-Ce/CoFe LDH. The experimental results match well with DFT calculations, proving that defect engineering, phase transformation, and electronic structure tailoring can result in a high efficiency of HER activity. Moreover, a cell constructed of CoFe LDH|V-Ce/CoFe LDH is capable of overall water splitting with a cell voltage as low as 1.65 V at 10 mA cm −2 and a remarkable long-term stability of 60 h. The plasma etching strategy can also be effective for other LDH-based electrocatalysts ( e.g. NiFe LDH and NiCo LDH), which demonstrates the universality of the strategy for improving HER performance. This work provides a simple but feasible pathway for designing alkaline HER electrocatalysts based on advanced LDH materials. Effective HER activity on layered double hydroxide nanosheets through a plasma etching strategy.