Journal
ACS NANO
Volume 16, Issue 8, Pages 12488-12499Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.2c03877
Keywords
selective water oxidation; seawater electrolysis; selective electrocatalysis; reduced graphene oxide; cobalt oxide; Pickering emulsion templating; phase contrast X-ray imaging
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Funding
- Canada Research Chair Foundation
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Fonds de Recherche du Quebec -Nature et Technologie [305938]
- Quebec Centre for Advanced Materials
- Canada Foundation for Innovation (CFI)
- NSERC
- National Research Council (NRC)
- Canadian Institutes of Health Research (CIHR)
- Government of Saskatchewan
- University of Saskatchewan
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This study developed a 3D macroporous reduced graphene oxide scaffold with cobalt oxide particles selectively deposited, which allows water molecules to access catalytic particles but prevents the diffusion of ions such as chlorine. The electrodes generated oxygen from simulated seawater with high pH and exhibited low chlorine generation.
The direct electrolysis of seawater is greatly inhibited by the oxidation of Cl- to free chlorine, an undesirable, corrosive byproduct. To suppress the parasitic interference of Cl- and any other ion, we developed a freestanding, electrically conducting, 3D macroporous reduced graphene oxide (rGO) scaffold with cobalt oxide particles selectively deposited on the internal walls of its closed pores (with an average diameter of similar to 180 mu m). The pore walls act as membranes composed of stacked rGO flakes; the nanochannels between rGO layers (size <1 nm) are permeable to water and gases while preventing the diffusion of dissolved ions such as Cl-. Due to this, the catalytic particles are selectively accessible to water molecules but not to ions, allowing electrolysis to occur without chlorine evolution. The electrodes developed exhibit a stable generation of O2 from simulated seawater at pH 14, reaching a specific current density of up to 25 A g-1 during continuous electrolysis with 89-98% Faradaic efficiency, while chlorine generation is below 6 ppm h-1, the sensitivity limit of the detection method employed. The strategy here proposed can be generalized to build electrodes that are inherently selective thanks to their architecture, with catalytically active particles loaded into closed pores with selective ion transport properties.
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