Simultaneous hydrogen and oxygen evolution reactions using free-standing nitrogen-doped-carbon–Co/CoOx nanofiber electrodes decorated with palladium nanoparticles. Issue 33 (21st June 2021)

• Record Type: Journal Article
• Authors: Barhoum, Ahmed; El-Maghrabi, Heba H.; Nada, Amr A.; Sayegh, Syreina; Roualdes, Stéphanie; Renard, Aurélien; Iatsunskyi, Igor; Coy, Emerson; Bechelany, Mikhael
• Is Part Of: Journal of materials chemistry. Volume 9:Issue 33(2021)
• Page Start: 17724
• Page End: 17739
• Publication Date: 2021-06-21
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1ta03704h
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Free-standing N-CNF–Co/CoO x electrodes were fabricated by electrospinning followed by thermal pyrolysis. Controlled atomic layer deposition of Pd NPs on these nanofibers significantly increased electrode electrochemical activity in water splitting. Abstract : Designing efficient electrode materials for electrochemical water splitting is the most critical challenge for next-generation hydrogen fuel production. This study describes the development of free-standing nitrogen-doped carbon nanofiber (N-CNF) electrodes that incorporated cobalt/cobalt oxide (Co/CoO x ) nanoparticles (NPs) and were decorated with palladium NPs (Pd NPs). These free-standing electrodes displayed high electrocatalytic activity during electrochemical water splitting, and were fabricated in three steps: (i) solution electrospinning of polyacrylonitrile (PAN)/cobalt acetate nanofiber mats; (ii) PAN/cobalt acetate nanofiber mat peroxidation and stabilization in air atmosphere followed by pyrolysis (carbonation) in nitrogen atmosphere; and (iii) decoration of the electrode surface with 5 and 10 nm Pd NPs by controlled atomic layer deposition (ALD) (100 and 200 cycles, respectively). The N-CNF–Co/CoO x –Pd electrode performance was tested in simultaneous hydrogen/oxygen evolution reactions (HER/OER) with an alkaline electrolyte solution (1 M KOH). The electrodes were as electroactive as Pt and IrO2 (reference electrodes) for overall electrochemical water splitting. The most efficient electrode displayed very interesting overpotential (100 mV and 160 mV @ j = 10 mA cm −2 for HER and OER, respectively), Tafel slope (33 and 113 mV dec −1 ), and exchange current density (1.15 and 22.4 mA cm −2 ) values. Interestingly, electrodes with the smallest Pd NP size (5 nm/100 ALD cycles) showed higher electrocatalytic activity for HER and OER than electrodes coated with bigger particles (10 nm/200 ALD cycles) and the reference Pt electrode. The effect of Co/CoO x NP encapsulation in the graphitic layers of N-CNFs and coating with Pd NPs on the electrode electrocatalytic activity are discussed in detail.