Flexible Bifunctional Electrode for Alkaline Water Splitting with Long-Term Stability

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Abstract

Progress in electrochemical water-splitting devices as future renewable and clean energy systems requires the development of electrodes composed of efficient and earth-abundant bifunctional electrocatalysts. This study reveals a novel flexible and bifunctional electrode (NiO@CNTR) by hybridizing macroscopically assembled carbon nanotube ribbons (CNTRs) and atmospheric plasma-synthesized NiO quantum dots (QDs) with varied loadings to demonstrate bifunctional electrocatalytic activity for stable and efficient overall water-splitting (OWS) applications. Comparative studies on the effect of different electrolytes, e.g., acid and alkaline, reveal a strong preference for alkaline electrolytes for the developed NiO@CNTR electrode, suggesting its bifunctionality for both HER and OER activities. Our proposed NiO@CNTR electrode demonstrates significantly enhanced overall catalytic performance in a two-electrode alkaline electrolyzer cell configuration by assembling the same electrode materials as both the anode and the cathode, with a remarkable long-standing stability retaining ∼100% of the initial current after a 100 h long OWS run, which is attributed to the “synergistic coupling” between NiO QD catalysts and the CNTR matrix. Interestingly, the developed electrode exhibits a cell potential (E10) of only 1.81 V with significantly low NiO QD loading (83 μg/cm2) compared to other catalyst loading values reported in the literature. This study demonstrates a potential class of carbon-based electrodes with single-metal-based bifunctional catalysts that opens up a cost-effective and large-scale pathway for further development of catalysts and their loading engineering suitable for alkaline-based OWS applications and green hydrogen generation.
Original languageEnglish
Pages (from-to)12339-12352
Number of pages14
JournalACS Applied Materials & Interfaces
Volume16
Issue number10
Early online date29 Feb 2024
DOIs
Publication statusPublished online - 29 Feb 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. Published by American Chemical Society.

Keywords

  • bifunctional and flexible electrode
  • macroscopically assembled carbon nanotube (CNT) ribbons
  • nickel oxides (NiO) quantum dots (QDs)
  • plasma-induced nonequilibrium electrochemistry (PiNE)
  • hydrogen evolution reaction (HER)
  • oxygen evolution reaction (OER)
  • water electrolysis
  • overall water splitting (OWS) in alkaline media
  • alkaline electrolyzer cell
  • long-term OWS stability

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