CeO2-Enhanced Surface Reconstruction of Ni3S2 Nanosheets for Improved Urea-Assisted Water Splitting Performance

Urea-assisted water splitting represents a prospective approach for sustainable hydrogen (H2) production. However, the challenge of designing highly efficient, durable, and economically viable bifunctional electrocatalysts hampers the practical implementation of this technology. In this work, we design a Ni3S2-CeO2 heterostructure catalyst on nickel foam, tailored to upgrade the efficiency and cost-effectiveness of urea-assisted electrolysis. The catalyst features a unique interconnected nanosheet architecture, which boosts its activity, obtaining 100 mA cm−2 for the urea oxidation reaction (UOR) with an overpotential of just 146 mV, and only 56 mV at 10 mA cm−2 for the hydrogen evolution reaction (HER). When employed at both electrodes in a urea electrolysis electrolyzer, the Ni3S2-CeO2/NF catalyst reaches a high current density of 500 mA cm−2 at 1.734 V. Experimental results and DFT calculations demonstrate that the Ni3S2-CeO2/NF heterogeneous interface facilitates electron redistribution and increases electronic density at Fermi level, thereby enhancing the conductivity. The incorporation of CeO2 facilitates the Ni3S2 surface reconstruction, forming NiOOH active species with abundant oxygen vacancies (OV) that optimize urea adsorption and improve UOR kinetics. Additionally, CeO2 reduces the hydrogen adsorption energy (ΔGH*), accelerating the HER process. These synergistic effects endow the Ni3S2-CeO2/NF catalyst to achieve outstanding bifunctional activity in UOR and HER, underscoring its potential for efficient urea-assisted electrolysis with low overpotentials at high current densities. This investigation supplies guidance for creating effective bifunctional catalysts for sustainable hydrogen production.