CeO₂ nanoparticles decorated on porous Ni–Fe bimetallic phosphide nanosheets for high-efficient overall water splitting

Figures & data

Figure 1. (a) Schematic illustration of the preparation of CeO₂/NiFeP/NF. (b) SEM, (c) TEM, and (d) HRTEM images of CeO₂/NiFeP. The inset of (c) shows a particle size distribution analysis. (e) XRD pattern of CeO₂/NiFeP. (f) N₂ adsorption/desorption isotherms and pore size distribution (the inset) of CeO₂/NiFeP. (g) EPR spectra of CeO₂/NiFeP and NiFeP.

Figure 2. High-resolution XPS spectra of (a) Ni 2p, (b) Fe 2p, (c) Ce 3d, and (d) O 1s for CeO₂/NiFeP/NF and NiFeP/NF.

Figure 3. (a) Polarization curves of the CeO₂/NiFeP/NF, NiFeP/NF, CeO₂/NiFe LDH/NF, NiFe LDH/NF, RuO₂/NF, and pure NF electrodes. (b) The corresponding Tafel plots. (c) Capacitive current densities at −0.25 V (vs. Hg/HgO) plotted against scan rates. (d) Chronopotentiometric test of the CeO₂/NiFeP/NF electrode at a current density of 50 mA cm⁻². The insets of (d) are SEM and TEM images of CeO₂/NiFeP after the durability test. (e) Polarization curves of the CeO₂/NiFeP/NF||CeO₂/NiFeP/NF electrolyzer and the Pt/C/NF||RuO₂/NF electrolyzer with a scan rate of 1 mV s^–1 in 1 M KOH.

Figure 4. (a) XRD pattern of the post-OER sample. (b) EPR spectra of CeO₂/NiFeP before and after the durability test. High-resolution XPS spectra of (c) Ce 3d, (d) O 1s, for the post-OER sample.

Figure 5. DFT simulation results. (a) Schematic profile of adsorption atomic configuration on the Ce–Ni_site during the OER elementary steps. (b) Free energy diagrams along the reaction pathways on Ce–Ni_site, Fe–Ni_site and CeO₂ (111) plane. (c) Representation of the theoretical overpotential as a function of the difference in O* and OH* adsorption Gibbs energies. (d) PDOS of Ce–Ni_site 3d orbitals and Fe–Ni_site 3d orbitals. The Fermi energy was set to zero.