A pyrazine-incorporated graphdiyne nanofilm as a metal-free electrocatalyst for the hydrogen evolution reaction. Issue 44 (10th September 2018)

• Record Type: Journal Article
• Authors: Sakamoto, Ryota; Shiotsuki, Ryo; Wada, Keisuke; Fukui, Naoya; Maeda, Hiroaki; Komeda, Joe; Sekine, Ryosuke; Harano, Koji; Nishihara, Hiroshi
• Is Part Of: Journal of materials chemistry. Volume 6:Issue 44(2018)
• Page Start: 22189
• Page End: 22194
• Publication Date: 2018-09-10
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c8ta07347c
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : A graphdiyne analogue featuring pyrazine as the aromatic center was synthesized under air using a liquid/liquid interfacial synthesis. It served as a metal-free electrocatalyst for the hydrogen evolution reaction (HER) from water. 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 ofPR-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 toPR-GDY afforded optical bandgap narrowing compared with the corresponding monomer. XPS provided a ratio of 2 : 1 for the sp and sp 2 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 m 2 g −1 and 0.8 nm, respectively. A series of electrochemical measurements were conducted to evaluate the HER activity ofPR-GDY . The HER performance ofGDY was only slightly better than that of glassy carbon, while that ofPR-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 H2 SO4, and –270 and −710 mV in 0.1 M NaHCO3 + 0.1 M Na2 CO3 . The present work demonstrates experimentally thatPR-GDY serves as a metal-free HER electrocatalyst, and manifests that pyridinic nitrogen enhances the electrocatalytic activity of carbon materials.