Carboxylated carbon nanotubes with high electrocatalytic activity for oxygen evolution in acidic conditions

Abstract

Since most electrocatalysts for oxygen evolution reaction (OER), except for precious metal oxides RuO2 and IrO2, are unstable in harsh acidic solutions, it is highly desirable to develop high‐performance OER electrocatalysts for acidic media, though it is still a big challenge. Herein, we report a simple strategy to produce carboxyl‐enriched multiwalled carbon nanotubes (COOH‐MWNTs) that exhibit stable and high electrocatalytic activities for OER in acidic solutions, showing an overpotential at a current density of 10 mA cm–2 and a Tafel slope as low as of 265 mV and 82 mV dec–1, respectively. As far as we are aware, these results represent the best OER performance for metal‐free electrocatalysts, even comparable to those of RuO2 and IrO2. We have further revealed the catalytic mechanism, which involves one electron lose from the COOH‐MWNTs catalyst at the beginning of the OER process to trigger H2O molecule oxidation by forming peralcohol, followed by the recapture of one electron from water molecule to oxidize water and to recover the initial state for the COOH‐MWNTs catalyst. The unravel of this new OER mechanism is important as it provides new insights into the crucial role of organic functional groups in electrocatalytic processes. Also, the mechanistic understanding can be used to guide the design and development of novel metal‐free catalysts for acidic OER electrocatalysis and beyond.

Construction of Core–Shell CoMoO4@γ-FeOOH Nanosheets for Efficient Oxygen Evolution Reaction

“…Newly developed OER catalysts can be classified into two types. Metal-free nanomaterials such as carbon nanotube (CNT), graphene, and boron nitride are reported as efficient OER electrocatalysts; however, these catalysts always require multi-step functionalization and are sensitive to pH in the system [7,8]. On the other hand, first-row transition metal-(Mn, Fe, Co, Ni, etc.)…”

Carboxylated Carbon Nanotube/Polyimide Films with Low Thermal Expansion Coefficient and Excellent Mechanical Properties

“…When the CNT content was 9 wt.%, the contact angle of CNT-PI film was increased to 81.17°, which is 45.62% higher than that of pure PI film. However, C-CNT was not so effective in improving the contact angle of PI films because the carboxyl group in C-CNT was hydrophilic, so the hydrophobicity of C-CNT was not as good as that of CNT [ 50 ]. As a result, the contact angle of C-CNT/PI films only increased to 76.23 when the content of C-CNT was 9%, which was 36.76% higher than that of pure PI films.…”

Recent advances in interface engineering strategy for highly‐efficient electrocatalytic water splitting

“…Therefore, further research and improvements are still needed to realize largescale industrial production and application. 57,176 Over the recent years, the interface engineering strategy has emerged as an extremely efficient approach to construct electrocatalysts with abundant and highly-active interfaces, which has broad application prospects. This review provided a systematic overview of the promising interface engineering strategies.…”

“…The development of catalysts with ultrahigh current density, low toxicity, high stability, and low cost is a crucial prerequisite for industrial hydrogen production, and most of the reported well‐designed catalysts cannot meet all the above requirements simultaneously. Therefore, further research and improvements are still needed to realize large‐scale industrial production and application 57,176 . Over the recent years, the interface engineering strategy has emerged as an extremely efficient approach to construct electrocatalysts with abundant and highly‐active interfaces, which has broad application prospects.…”