Hierarchical nanocomposites of nickel/iron-layered double hydroxide ultrathin nanosheets strong-coupled with nanocarbon networks for enhanced oxygen evolution reaction

Nickel/iron-layered double hydroxide (NiFe-LDH) for oxygen evolution reaction (OER) was hindered insufficient active sites, low inherent conductivity and poor stability. Herein, we innovatively report a facile and costeffective in situ synthesis strategy to prepare ultrathin NiFe-LDH nanosheets coupled onto hierarchical nano carbon networks consisting of carbon nanotube and graphene nanoribbon (NiFe-LDH/CNT@GNR) forming a porous interconnected nanocomposite. Partial unzipping of CNT induced by strong oxidation leads to the creation of GNR nanolayers tightly attached to the retained CNT framework, where GNR achieves high surface areas to load NiFe-LDH nanosheets and inner CNT still enables high conductivity. The CNT@GNR nanocarbon network not only enhances accessible electrochemical active area and mass transfer, but also provides high-efficiency conductive brackets with interlinked electron transfer pathways and achieve the strong interface coupling with NiFe-LDH nanosheets, synergistically resulting in rapid electrocatalytic kinetics. Moreover, NiFe-LDH nanosheets are tightly anchored on the surface of nanocarbon networks, greatly enhanced the stability of NiFe-LDH. NiFe-LDH/CNT@GNR exhibits remarkable OER activity with a low overpotential of 261 mV at 10 mA cm(-2), Tafel slope of 78 mV dec(-1), and high stability for up to 17 h, superior to most LDH-based OER catalysts reported, and even better than commercial RuO2. Therefore, the facile synthesis and excellent hierarchical architecture endow NiFe-LDH/CNT@GNR nanocomposites as advanced electrocatalysts for outstanding OER performance. Most importantly, the design provides a simple but universal strategy to yield high performance of NiFe-LDH catalysts, facilitating the commercial process of non-noble catalysts for OER.

Automated summary

A facile and cost-effective synthesis strategy was developed to prepare NiFe-LDH/CNT@GNR nanocomposites with excellent OER performance and stability. The hierarchical nanocomposite structure, including porous nanocarbon networks and tightly anchored NiFe-LDH nanosheets, enables rapid electrocatalytic kinetics and high stability.