Structure And Electrocatalytic Properties Of Co（OH）₂Nanosheet

Sustainable development of human is facing serious issues of energy and environmental, and the use of light or electricity to split water into hydrogen and oxygen is an effective way to resolve these crises. However, the water-splitting kinetics of oxygen production bottleneck has restricted the efficiency of the optical or electrical catalytic decomposition of water, and therefore sought a high oxygen production efficiency of the catalyst has become crucial. Currently, efficient oxygen production catalysts are IrO2, RuO2, etc., but because of its low earth reserves and high production cost limit their widespread application. So, how to find efficient, stable, environmentally friendly and inexpensive preparation of oxygen production catalyst is scientific issues need to be resolved.Inspired by graphene, when the transition metal hydroxide or oxide is thin-layered, it will exhibit peculiar physical and chemical properties, for example, after be thin-layered, Co3O4shows excellent electro-catalytic activity of oxygen production; NiCo2O4nanosheet with new nuclear ring structure exhibits superior catalytic properties for OER. In this thesis, y-CoOOH is thin-layered by hydrothermal method, showing excellent performance of water electrolysis; In addition, a-Co(OH)2compounded with graphene exhibited good electrocatalytic properties and improved the efficiency of OER. Therefore, we use characterizations methods, like TEM, XRD, XAFS, Raman and so on to explore the relationship between electronic structure and its electro-catalytic properties of a-Co(OH)-2and its composite material. Specific contents are as follows:1.The study of the electrocatalytic properties of ultra-thin y-CoOOH nanosheetBy means of a oriented growth strategy, we have realized atomically thin y-CoOOH nanosheet with half-unit-cell thickness. According to the electrochemical results, it show that the y-CoOOH nanosheet can significantly improve the catalytic efficiency of OER and reduce the oxygen evolution overpotential. The results of XAFS show that the deletion of Co ions can provide active sites of electrocatalytic reactions; Co valence is decreased to improve the oxidation property and lead to the water oxidized to oxygen more easily, thereby increasing the electro-catalytic efficiency.2.The study of the electrocatalytic properties of rGO/α-Co(OH)2nanosheet By the way of the template-assisted oriented growth strategy, we have successfully synthesized rGO/p-Co(OH)2nanosheet. The electrochemical analysis show that onset potential of the rG0/a-Co(OH)2nanosheet is lower than the onset potential of bulk and the Co3O4nanoparticle. When the current density is10mA/cm2, the overpotential of the rGO/α-Co(OH)2nanosheet is lower than bulk’s as50mV and lower than Co3O4nanoparticle’s as130mV. What’s more, the mass activity of rGO/α-Co(OH)2nanosheet was higher than the Co3O4nanoparticle’s of almost50times and performed powerful electrocatalytic reactivity. It is foreseeable that rGO/α-Co (OH)2nanosheets has rich reserves and efficient catalytic activity for OER, which will have broad applications in the field of electro-catalytic hydrolysis.