Engineering electron redistribution in NiCoP/Ti3C2Tx MXene through CeO2 coupling to boost HER and OER performance

Designing transition metal phosphides (TMPs) with remarkable performance and high stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) plays a significant role in the commercial application of water splitting. Bimetallic phosphide (NiCoP) exhibits favorable electrocatalytic activity; however, it still suffers from intrinsic limitations such as insufficient intrinsic activity, inferior electrical conductivity, and a tendency toward particle agglomeration. To address these issues, a CeO 2 modified NiCoP particle catalyst (referred to as CeO 2 -NiCoP/Ti 3 C 2 T x ) loaded on a few layers of Ti 3 C 2 Tx MXene was synthesized using an HCl/LiF etching and hydrothermal phosphorization method. The CeO 2 -NiCoP/Ti 3 C 2 T x catalyst exhibits significantly lower overpotentials (287 mV for OER and 147 mV for HER) to achieve a current density of 10 mA cm −2 . Moreover, the catalyst demonstrates outstanding durability, with 93.6% and 84.6% retention of its activity after 27 h of OER and 25 h of HER, respectively.The favorable performance of CeO 2 -NiCoP/Ti 3 C 2 T x in HER and OER can be attributed to several advantages. Few-layer Ti 3 C 2 T x enhances the electrical conductivity of the material, and its large specific surface area prevents particle agglomeration, thus improving the material stability.The -O/-OH functional groups on the surface of Ti 3 C 2 T x endow the material with strong hydrophilicity, which facilitates the full contact between active sites and the electrolyte and accelerates the mass transfer and charge transfer kinetics. CeO 2 effectively optimizes the adsorption energy of NiCoP toward hydrogen intermediates by regulating the microelectronic structure of NiCoP, thereby boosting the HER kinetics.