Hollow Co₃O₄/CeO₂ Heterostructures in Situ Embedded in N-Doped Carbon Nanofibers Enable Outstanding Oxygen Evolution

Abstract

Exploring highly efficient and cost-effective electrocatalysts with more feasible synthesis strategies toward oxygen evolution reaction (OER) is highly desirable for a broad range of advanced sustainable energy conversion systems. Herein, we develop a feasible electrospinning strategy for the facile fabrication of a Co 3 O 4 /CeO 2 heterostructure in situ embedded in N-doped carbon nanofibers (h-Co 3 O 4 /CeO 2 @N-CNFs) as a high-performance electrocatalyst for the OER. Unlike previously reported Co 3 O 4 /CeO 2 composites, the as-prepared Co 3 O 4 /CeO 2 heterostructure presents hollow and porous features. The nanopores can develop within Co 3 O 4 /CeO 2 nanocrystals with an analogous mechanism to void formation in the Kirkendall effect. Electrochemical measurements demonstrate that h-Co 3 O 4 /CeO 2 @N-CNFs can enable high OER activity with a low overpotential of 310 mV to achieve 10 mA cm −2 current density and good stability that can maintain 40 000 s without perceptible attenuation, outperforming those of the commercial RuO 2 catalyst. The outstanding OER performance originates from the important synergies by combining hollow Co 3 O 4 /CeO 2 heterostructures and three-dimensional porous N-CNF networks.

Electronic modulation and interface engineering of electrospun nanomaterials‐based electrocatalysts toward water splitting

“…In fact, to tune the OER performance, the interface between the active electrocatalyst and CNFs is very important 171‐198 . Li et al 197 developed an electrospinning and carbonization process to prepare CoFe 2 O 4 nanoparticles encapsulated in N‐doped CNFs (CoFe 2 O 4 /NCNFs) as an OER electrocatalsyt.…”

“…As CeO 2 usually possesses a good redox capability, it can be utilized to tune the OER activity of Co 3 O 4 materials through an interface effect. Toward this end, a distinct heterostructure consisting of Co 3 O 4 and CeO 2 embedded in N‐doped CNFs (Co 3 O 4 /CeO 2 @NCNFs) has been fabricated as OER electrocatalyst 198 . This catalyst for OER application has the following advantages: (1) the interface between CeO 2 and Co 3 O 4 affords abundant exposed active sites and facilitates the charge transport to enhance the OER activity.…”

“…(G) Comparison of the stability test of Co 3 O 4 /CeO 2 @N‐CNFs and commercial RuO 2 catalyst. Reproduced with permission: Copyright 2019, American Chemical Society 198 . CNF, carbon nanofiber; LSV, linear sweep voltammetry; OER, oxygen evolution reaction…”

Ce‐Doped Ordered Mesoporous Cobalt Ferrite Phosphides as Robust Catalysts for Water Oxidation

“…[14][15][16] However,t he relatively high overpotential of the current catalysts is far from sat-isfactory. [17][18][19] To increase the performance of electrocatalysts, doping suitable components is considered as an efficient way to regulate the electronic structure and optimize the structure morphology. [20][21][22] Ce with variable valence exhibits good conductivity and high oxygen storagea bility,w hich offerst he opportunity to generate strong electron coupling with other materials,t hus enhancing the electrocatalytic performance for OER.…”

“…The bimetallic transition metal phosphides exhibit superior OER activity owing to their intrinsic electronic conductivity . However, the relatively high overpotential of the current catalysts is far from satisfactory . To increase the performance of electrocatalysts, doping suitable components is considered as an efficient way to regulate the electronic structure and optimize the structure morphology .…”