Ruthenium anchored on carbon nanotube electrocatalyst for hydrogen production with enhanced Faradaic efficiency

Do Hyung Kweon,Jong-Pil Jeon,Jong-Beom Baek,Mahmut Sait Okyay,Hyuk-Jun Noh,Seok-Jin Kim,Javeed Mahmood,Noejung Park

doi:10.1038/s41467-020-15069-3

Abstract

Developing efficient and stable electrocatalysts is crucial for the electrochemical production of pure and clean hydrogen. For practical applications, an economical and facile method of producing catalysts for the hydrogen evolution reaction (HER) is essential. Here, we report ruthenium (Ru) nanoparticles uniformly deposited on multi-walled carbon nanotubes (MWCNTs) as an efficient HER catalyst. The catalyst exhibits the small overpotentials of 13 and 17 mV at a current density of 10 mA cm–2 in 0.5 M aq. H2SO4 and 1.0 M aq. KOH, respectively, surpassing the commercial Pt/C (16 mV and 33 mV). Moreover, the catalyst has excellent stability in both media, showing almost “zeroloss” during cycling. In a real device, the catalyst produces 15.4% more hydrogen per power consumed, and shows a higher Faradaic efficiency (92.28%) than the benchmark Pt/C (85.97%). Density functional theory calculations suggest that Ru–C bonding is the most plausible active site for the HER.

Highlights

Developing efficient and stable electrocatalysts is crucial for the electrochemical production of pure and clean hydrogen
Commercial multi-walled carbon nanotubes (MWCNTs) were mildly oxidized with nitric acid to introduce oxygenated functional groups on the surface of MWCNT
Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to analyze the formation of Ru carboxylate complex and local structural environment of Ru@MWCNT catalyst before and after heat-treatment (Supplementary Fig. 1)

Summary

Introduction

Developing efficient and stable electrocatalysts is crucial for the electrochemical production of pure and clean hydrogen. To ensure the hydrogen evolution reaction (HER) is efficient and continuous, the catalyst must promote proton reduction with minimal overpotential, to minimize additional energy consumption[6,7]. This requirement has made the efficient production of hydrogen using electrochemical catalysts a challenge for scientists over the last several decades[8,9,10,11,12,13,14]. In order to replace Pt, efforts have been devoted to developing earth abundant element-based catalysts for HER, e.g., phosphates[18], carbides[19,20], oxides[21], and transition metal sulfides[15,22] They typically suffer from both limited electrochemical activity and durability.

Methods

Results

Conclusion