Strongly coupled hollow-oxide/phosphide hybrid coated with nitrogen-doped carbon as highly efficient electrocatalysts in alkaline for hydrogen evolution reaction

Abstract

Exploring and developing highly efficient, cost-efficient and stable electrocatalyst for hydrogen evolution reaction (HER) in alkaline solutions is a meaningful but challenging task. Herein, we present the design and synthesis of a novel hollow-cerium oxide/nickel phosphide heterostructure encapsulated by ultrathin nitrogen-doped carbon layer (H-CeO2-x/Ni2P@NC) as efficient electrocatalysts for HER in alkaline media. Both experimental and theoretical analysis suggests that the presence of CeO2-x not only serves as a site for adsorption of water molecules, but also has a strong ability to cleave H-O bonds in H2O molecules. More importantly, X-ray photoelectron spectroscopy (XPS) and differential charge density showed that the strong interaction between the components caused the change of charge distribution at the interface, that is, the charge accumulated to the phosphorus atoms. And that will greatly optimize the adsorption strength of the hydrogen intermediate species on the Ni2P surface. In addition, the nitrogen-doped ultrathin carbon layer on the outer surface can not only effectively accelerate the electron transfer to the active site, but avoid the catalyst deactivation caused by the falling off or segregation of the active species. Therefore, the as-prepared H-CeO2-x/Ni2P@NC ternary hybrid electrode exhibit outstanding HER catalytic performance with low onset potential, high catalytic activity and excellent stability. Our work might shed some new lights on the design of efficient and robust three-dimensional hybrid catalyst for a variety of electrochemical applications.