Platinum-Anchored Iron Oxide Nanostructures for Efficient Hydrogen Evolution Reaction in Acidic Media

Metal oxides have been attracting extensive interest in the design and engineering of effective electrocatalysts owing to their unique electronic structure and natural abundance. However, the limited electrical conductivity and sluggish electrontransfer kinetics have hampered their widespread applications. These issues can be mitigated by structural engineering with the incorporation of select precious metal species. Herein, iron oxide nanostructures decorated with platinum species are prepared by the facile thermal annealing of a MIL-101 precursor along with the addition of a controlled amount of PtCl4 and exhibit apparent electrocatalytic activity toward the hydrogen evolution reaction in 0.5 M H2SO4. The best sample needs only an ultralow overpotential of -15 mV to reach the current density of 10 mA cm(-2), along with a low Tafel slope of 25.4 mV dec(-1), a performance markedly better than that of commercial 20 wt % Pt/C. This is ascribed to the synergistic interactions between the Pt and Fe2O3 scaffold that impact the material's electrical conductivity and electron-transfer kinetics and the Cl residuals that regulate the adsorption free energy of H, as confirmed in computational studies based on density functional theory. Results from this study highlight the unique potential of metal oxide-based nanocomposites as high-performance, low-cost electrocatalysts for electrochemical energy technologies where the performance can be further regulated by anion residuals.