Exploring the mechanism of electrocatalytic water oxidation on CoO decorated Ti3C2Tx nanoplatelets

Abstract

In this work, we report the facile preparation of ultrathin cobalt oxide layer decorated Ti3C2Tx nanoplatelets (CoO@Ti3C2Tx) and explore the mechanism of water oxidation reaction. Cobalt ions form complexes in the presence of ammonia, which lead to the uniform anchoring of the cobalt precursor on the surface of the nanoplatelets. Randles-Sevcik analysis revealed that water oxidation on CoO@Ti3C2Tx likely first undergoes a one-electron transfer pathway to form hydroxyl radical, two of which then combine to produce hydrogen peroxide. The latter, successfully detected via strip colorimetry, further disproportionately or electrochemically transforms to gaseous oxygen. The water oxidation reaction on CoO@Ti3C2Tx nanoplatelets with a low amount of ∼4%w.t. cobalt loading reaches 10 mA cm−2 at 1.68 V with a small Tafel slope of 72 mV dec−1 and robust stability with only 5.14% decay over 12 h. This work not only provides an important implication on the design and preparation of the cost-effective, efficient and durable MXene based electrocatalysts but also demonstrated the specific pathway of water oxidation reaction.