Highly efficient and robust noble-metal free bifunctional water electrolysis catalyst achieved via complementary charge transfer

Nam Khen Oh,Hyesung Park,Jihyung Seo,Sangjin Lee,Hyung-Jin Kim,Ungsoo Kim,Junghyun Lee,Young-Kyu Han

doi:10.1038/s41467-021-24829-8

Abstract

The operating principle of conventional water electrolysis using heterogenous catalysts has been primarily focused on the unidirectional charge transfer within the heterostructure. Herein, multidirectional charge transfer concept has been adopted within heterostructured catalysts to develop an efficient and robust bifunctional water electrolysis catalyst, which comprises perovskite oxides (La0.5Sr0.5CoO3–δ, LSC) and potassium ion-bonded MoSe2 (K-MoSe2). The complementary charge transfer from LSC and K to MoSe2 endows MoSe2 with the electron-rich surface and increased electrical conductivity, which improves the hydrogen evolution reaction (HER) kinetics. Excellent oxygen evolution reaction (OER) kinetics of LSC/K-MoSe2 is also achieved, surpassing that of the noble metal (IrO2), attributed to the enhanced adsorption capability of surface-based oxygen intermediates of the heterostructure. Consequently, the water electrolysis efficiency of LSC/K-MoSe2 exceeds the performance of the state-of-the-art Pt/C||IrO2 couple. Furthermore, LSC/K-MoSe2 exhibits remarkable chronopotentiometric stability over 2,500 h under a high current density of 100 mA cm−2.

Highlights

The operating principle of conventional water electrolysis using heterogenous catalysts has been primarily focused on the unidirectional charge transfer within the heterostructure
LSC and K-MoSe2 were synthesized via the sol-gel method and molten-metal-assisted intercalation[26], respectively; the as-prepared LSC and K-MoSe2 were mixed via ball milling at specified weight percent ratios
All relevant components (La, Sr, Co, O, Mo, Se, and K) were uniformly distributed in the heterostructure, and the elemental compositions of each component of LSC/K-MoSe2 obtained from the transmission electron microscopy (TEM)–energy-dispersive spectroscopy (EDS) spectrum are presented in Supplementary Fig. 2 with the prescribed elemental ratio

Summary

Introduction

The operating principle of conventional water electrolysis using heterogenous catalysts has been primarily focused on the unidirectional charge transfer within the heterostructure. Multidirectional charge transfer concept has been adopted within heterostructured catalysts to develop an efficient and robust bifunctional water electrolysis catalyst, which comprises perovskite oxides (La0.5Sr0.5CoO3–δ, LSC) and potassium ion-bonded MoSe2 (K-MoSe2). Excellent oxygen evolution reaction (OER) kinetics of LSC/K-MoSe2 is achieved, surpassing that of the noble metal (IrO2), attributed to the enhanced adsorption capability of surface-based oxygen intermediates of the heterostructure. Most bifunctional heterostructure-based catalysts have primarily utilized unidirectional charge transfer effects between heterostructure components[17,18], which can potentially limit an optimized electronic structure to achieve ideal HER and OER catalytic activities. The integrated overall water electrolysis exhibits excellent operational stability (over 2,500 h) without the decomposition of the catalyst under a high current density of 100 mA cm−2

Methods

Results

Conclusion