Issue 44, 2018

A pyrazine-incorporated graphdiyne nanofilm as a metal-free electrocatalyst for the hydrogen evolution reaction

Abstract

A graphdiyne (GDY) analogue that features pyrazine as the aromatic core (PR-GDY) was synthesized under air using a liquid/liquid interfacial synthesis. Optical microscopy, SEM, and AFM revealed the sheet morphology of PR-GDY with a typical thickness of 20 nm in AFM, while TEM disclosed its amorphous nature. It served as a metal-free electrocatalyst for the hydrogen evolution reaction (HER) from water. The presence of the butadiynyl linker and terminal ethynyl group, respectively, was confirmed by Raman spectroscopy. Polymerization to PR-GDY afforded optical bandgap narrowing compared with the corresponding monomer. XPS provided a ratio of 2 : 1 for the sp and sp2 carbons. Moreover, a single Gaussian was fitted with the N 1s peak, ascribable to the pyridinic nitrogen. Such selective doping of heteroatoms is hard to realize in carbon materials. PR-GDY was subjected to TGA, such that its thermal stability up to 300 °C was confirmed. N2 adsorption–desorption isotherms featured a typical type I adsorption behavior with micropores, with a Brunauer–Emmett–Teller surface area and mean pore size of 408 m2 g−1 and 0.8 nm, respectively. A series of electrochemical measurements were conducted to evaluate the HER activity of PR-GDY. The HER performance of GDY was only slightly better than that of glassy carbon, while that of PR-GDY was improved significantly in both acidic and basic aqueous media with an onset potential of −275 mV (vs. the reversible hydrogen electrode, RHE), and −475 mV to achieve a current density of 10 mA cm−2 in 0.5 M H2SO4, and –270 and −710 mV in 0.1 M NaHCO3 + 0.1 M Na2CO3. The present work demonstrates experimentally that PR-GDY serves as a metal-free HER electrocatalyst, and manifests that pyridinic nitrogen enhances the electrocatalytic activity of carbon materials.

Graphical abstract: A pyrazine-incorporated graphdiyne nanofilm as a metal-free electrocatalyst for the hydrogen evolution reaction

Supplementary files

Article information

Article type
Paper
Submitted
30 júl 2018
Accepted
23 aug 2018
First published
23 aug 2018

J. Mater. Chem. A, 2018,6, 22189-22194

Author version available

A pyrazine-incorporated graphdiyne nanofilm as a metal-free electrocatalyst for the hydrogen evolution reaction

R. Sakamoto, R. Shiotsuki, K. Wada, N. Fukui, H. Maeda, J. Komeda, R. Sekine, K. Harano and H. Nishihara, J. Mater. Chem. A, 2018, 6, 22189 DOI: 10.1039/C8TA07347C

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