Complementary behaviour of EDL and HER activity in functionalized graphene nanoplatelets

Green hydrogen production is a vital requirement of the upcoming hydrogen fuel-based locomotion and economy. Water electrolysis facilitated by electricity derived from renewable sources and direct solar-to-hydrogen conversion centred on photochemical and photoelectrochemical water splitting is a pro...

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Bibliographic Details
Published in:Nanoscale 2020-01, Vol.12 (3), p.179-18
Main Authors: Puthirath, Anand B, Shirodkar, Sharmila, Fei, Minfei, Baburaj, Abhijit, Kato, Keiko, Saju, Sreehari K, Prasannachandran, Ranjith, Chakingal, Nithya, Vajtai, Robert, Yakobson, Boris I, Ajayan, Pulickel M
Format: Article
Language:English
Subjects:
Catalysts
Catalytic activity
Electric double layer
Electrolysis
First principles
Free energy
Graphene
Hydrogen
Hydrogen evolution reactions
Hydrogen fuels
Hydrogen production
Locomotion
Noble metals
Production methods
Strength
Water splitting
X ray photoelectron spectroscopy
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Summary:Green hydrogen production is a vital requirement of the upcoming hydrogen fuel-based locomotion and economy. Water electrolysis facilitated by electricity derived from renewable sources and direct solar-to-hydrogen conversion centred on photochemical and photoelectrochemical water splitting is a promising pathway for sustainable hydrogen production. All these methods require a highly active noble metal catalyst to make the water-splitting process more energy-efficient and in order to make it economical, metal-free hydrogen evolution catalysts such as graphene nanoplatelets (GNPs) are essential. Herein, we report the effect of a range of functionalizations on the catalytic properties of graphene nanoplatelets (GNPs) for the hydrogen evolution reaction (HER). We also account for the effect of functionalization on the strength of the electrical double layer formation on the surface of functionalized GNPs. It is observed that the catalytic activity and the electrical double layer strength are inversely related to each other. Our first-principles-based density functional theoretical (DFT) modelling unravels the origin of the observed electrocatalytic activity and its trend and the strength of the electrical double layers in terms of free energy changes during the ion absorption/desorption events on the electrode surface. Based on our observations, minimizing the electrical double layer strength is identified as an approach to improve the catalytic performance of the catalysts. The hydrogen evolution reaction (HER) and electrical double layer capacitance (EDLC) properties show a mutually exclusive behaviour in pristine and functionalized of graphene nanoplatelets.
ISSN:2040-3364
2040-3372
DOI:10.1039/c9nr08102j