Enhancing Hydrogen Evolution Electrocatalytic Performance in Neutral Media via Nitrogen and Iron Phosphide Interactions

Siyu Zhao,Wenyao Li,Guoliang Chai,Ivan P Parkin,Dan J L Brett,Ruikuan Xie,Guanjie He,Ryan Wang,Manni Yang,Xingyu He,Liqun Kang

doi:10.1002/smsc.202100032

Abstract

It remains a challenge to develop efficient electrocatalysts in neutral media for hydrogen evolution reaction (HER) due to the sluggish kinetics and switch of the rate determining step. Although metal phosphides are widely used HER catalysts, their structural stability is an issue due to oxidization, and the HER performance in neutral media requires improvement. Herein, a new material, i.e., grapevine‐shaped N‐doped iron phosphide on carbon nanotubes, as an efficient HER catalyst in neutral media is developed. The optimized catalyst shows an overpotential of 256 mV at a large current density of 65 mA cm−2, which is even 10 mV lower than that of the commercial 20% Pt/C catalyst. The excellent performance of the catalyst is further studied by combined computational and experimental techniques, which proves that the interaction between nitrogen and iron phosphides can provide more efficient active structures and stabilize the metal phosphide electrocatalysts for HER.

Highlights

IntroductionProviding sufficient energy to the growing world population with adsorption free energy of the electrocatalysts.[17,18,19] The mechanism of HER in acid media is well studied and a volcano plot for metals was achieved for the further optimization of electrocatalysts.[1,20,21] the mechanism of a minimum impact on the environment requires the develop- HER in alkaline and neutral media is more complicated with ment of renewable energy sources.[1,2,3] Hydrogen can an additional water dissociation energy barrier slowing down behave as a clean fuel and as an important raw material the reaction kinetics, it is worth further investigating
The ratio of iron source and carbon nanotubes (CNTs) was optimized, and the morphology of materials were characterized by transmission electron microscopy (TEM)
The material has integrated advantages of abundant and efficient active sites provided by the unique structure that promoted intrinsic catalytic activity

Summary

Introduction

Providing sufficient energy to the growing world population with adsorption free energy of the electrocatalysts.[17,18,19] The mechanism of HER in acid media is well studied and a volcano plot for metals was achieved for the further optimization of electrocatalysts.[1,20,21] the mechanism of a minimum impact on the environment requires the develop- HER in alkaline and neutral media is more complicated with ment of renewable energy sources.[1,2,3] Hydrogen can an additional water dissociation energy barrier slowing down behave as a clean fuel and as an important raw material the reaction kinetics, it is worth further investigating. Wang et al developed Fe0.5Co0.5P nanoparticles supported on mildly oxidized multiwall carbon nanotubes (CNTs) as HER catalysts.[31] The X-ray photoelectron spectroscopy (XPS) results showed the formation of Fe–OH species during HER reaction in 1 M KOH, which is not considered as a good HER catalyst and weakened the catalytic performance. Further development is required for metal phosphide electrocatalysts to stabilize their structure under working conditions and promote their application for HER in neutral media, especially under high current densities. We develop a facile strategy to stabilize the structure of metal phosphides during HER and promote intrinsic catalytic activity by introducing N atoms into the structure of the FeP material as HER electrocatalysts for neutral media. The stabilized structure is further proved by ex situ X-ray fine structure analysis

Results and Discussion

Conclusion

Data Availability Statement