Ultrathin Ti2NTx MXene-wrapped MOF-derived CoP frameworks towards hydrogen evolution and water oxidation

Abstract Hydrogen evolution is of great significance for reducing carbon emissions and realizing carbon-neutral. Hydrogen evolution reaction (HER) by water splitting has no carbon emissions and pollution, but it is still necessary to reduce cost and enhance catalytic activity. Herein, we report an ultra-thin Ti2NTx MXene-wrapped metal-organic frameworks (MOFs)-derived CoP composite (Ti2NTx@MOF-CoP), which is a bifunctional catalyst with low cost and high activity. We synthesize the Ti2NTx@MOF-CoP composite by phosphating the precursor ZIF-67 self-assembled with Ti2NTx MXene nanosheets. The Ti2NTx@MOF-CoP electrode shows competitive hydrogen evolution performance in a wide pH-range (current density of 10 mA cm−2) and has a low overpotential (η) of 112 mV in pH = 14 especially. The Ti2NTx@MOF-CoP electrode for OER also has a low η = 241 mV at 50 mA cm−2. Based on the bifunctional activity of Ti2NTx@MOF-CoP in alkaline, we set a dual-electrode configuration for HER and OER. It has a bias of 1.61 V at 10 mA cm−2, with impressive catalytic stability during a 20 h measurement. MOFs-derived CoP has a large specific surface area and strong catalytic activity. Ti2NTx as a novel member of the MXene family not only can increase the active sites, but also can improve the stability of heterojunction catalysts. It reveals that the Ti2NTx@MOF-CoP composite has great potential in hydrogen evolution and water oxidation, thus reducing carbon emissions and protecting the environment.