Dual enhancement of water oxidation catalysis by MXene in the grass-like ZnCoCH@Ti3C2Tx heterostructure

In space, electrolysis of water is one of the main methods to generate oxygen (for life support), and its harsh environment places higher demands on the oxygen evolution reaction (OER). Cobalt-based carbonate hydroxides (CCH) have emerged as new candidates for OER catalysts in recent years. However, disadvantages such as poor catalytic activity and easy agglomeration of pristine CCH hinder its application in catalysis. Herein, we synthesized ZnCoCH@Ti3C2Tx heterostructure with a unique structure of grass-like Zn-doped bimetallic carbonate hydroxides grown in situ on MXene by a solvothermal method. The ZnCoCH@Ti3C2Tx electrocatalyst in 1 M KOH shows a low overpotential (280 mV) at 10 mA cm−2, a small Tafel slope (46.2 mV dec-1) and a Faraday efficiency of nearly 100 %. The experimental and DFT calculations show that MXene plays a dual enhancing role as a conductive carrier and a reducing agent in improving the OER performance. As a conductive carrier, MXene alleviates the agglomeration of ZnCoCH and enhances the conductivity and charge transfer ability of the heterostructure. As a reducing agent, MXene provides more redox sites by reducing ZnCoCH and promotes the adsorption of intermediate species on the catalyst. Zn is not only an economical and eco-friendly metal but also may have anti-toxicity. This study provides a reasonable idea for the design of efficient, economical, green and poison-resistant OER catalysts for electrolytic water.