Cerium-incorporated Ni2P nanosheets for enhancing hydrogen production from overall water splitting and urea electrolysis

Abstract

Hydrogen production from water splitting is a green and efficient technology for storing clean energy. Herein, cerium-incorporated Ni 2 P nanosheets are designed as trifunctional electrocatalysts to generate hydrogen by hydrothermal self-oxidation of surface nickel foam (NF) in pure water to in-situ form Ni(OH) 2 nanosheets, followed by incorporation of Ce and phosphorization. The prepared material exhibits excellent electrocatalytic performance in hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR). When the current density is 100 mA cm −2 , the UOR potential of Ce-Ni 2 P is 1.473 V lower than that in the OER (1.731 V), suggesting a great potential to replace the sluggish OER for overall water splitting. Moreover, the Ce-Ni 2 P/NF can be applied to the electrochemical treatment of real urine electrolysis with similar performance to the urea electrolysis. Such remarkable performance is attributed to the incroporation of Ce with "Ce 3+ /Ce 4+ redox pairs", which can not only provide abundant reactive sites by the charge transfer appearance of defect sites, but also offer an effective buffering space for the pre-oxidation process from Ni 2+ to Ni 3+ . It is thus beneficial for overall water splitting and coupled urea electrolysis, providing a promising candidate for urine wastewater treatment and clean energy production. • Nanosheets are prepared by hydrothermal self-oxidation of NF in pure water. • Ce leads to the lattice distortion of Ce-Ni2P and generates abundant defects. • Such interactions between Ce and Ni2P promote HER and OER/UOR performance. • Ce-Ni2P/NF can be applied for urine wastewater treatment.