Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 13, Issue 29, Pages 34093-34101Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c06187
Keywords
chlorine evolution reaction; platinum oxide; surface Pt/PtOx ratio; polarity reversal; scanning electrochemical microscopy
Funding
- National Research Foundation of Korea [NRF-2019R1C1C1003435]
- Ministry of Trade, Industry and Energy (MOTIE, Korea) [20011360]
- Korea Evaluation Institute of Industrial Technology (KEIT) [20011360] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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This study investigated the competition between the chlorine evolution reaction (CIER) and oxygen evolution reaction (OER) on Pt electrodes in dilute NaCl solutions, revealing the distinct roles of Pt(0) and Pt/PtOx in current efficiency and reversal intervals, with polarity switching affecting the selectivity for CIER. The use of SECM and XPS techniques provided insight into the mechanisms of CIER and OER, highlighting the importance of the surface Pt/PtOx ratio on the efficiency and selectivity of the reactions.
This study investigated competing chlorine evolution reaction (LEER) and oxygen evolution reaction (OER) on Pt electrodes under variable polarity reversal intervals (+/- 16.7 mA cm(-2), 30-600 s) in the context of distinctive roles of Pt(0) and Pt/PtOx on the surface in dilute (0.1 M) NaCl solutions. The substrate generation/tip collection mode of scanning electrochemical microscopy (SECM) quantified the current efficiency (CE) of ClER with a large tip-to-substrate distance (>500 mu m) to avoid intervention of bubbles and spatial variations. Surface interrogation SECM using [Ru(NH3)(6)](2+/3+) coupled with X-ray photoelectron spectroscopy (XPS) identified the Pt4+-enriched surface of Pt/PtOx with a bilayer structure to give more efficient regeneration of Pt(0) under the shorter reversal interval. The in situ SECM complemented bulk electrolysis and XPS to demonstrate that CIER on Pt(0) and OER on Pt/PtOx primarily determine the CE of CIER, in agreement with a kinetic model. The descriptive role of surface Pt/PtOx ratio rationalized the enhanced selectivity for CIER upon the polarity switching, being independent on a scaling relationship. The current reversal (not allowed to IrO2 electrodes) also alleviated calcareous scale deposit in the electrolyte with hardness.
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