Ultralow-content Pt nanodots/Ni3Fe nanoparticles: interlayer nanoconfinement synthesis and overall water splitting

Abstract

Minimizing precious metal loading into electrocatalysts for water splitting is vital to promoting hydrogen energy technology toward practical applications. Low-content loading of precious-metal electrocatalysts is achieved by decorating precious metal nanostructures on co-electrocatalysts typically via surface confinement. Here, an electrocatalyst of ultralow-content Pt nanodots (0.71 wt%)/Ni₃Fe nanoparticles on reduced oxidation graphene (Pt/Ni₃Fe/rGO) is constructed for overall water splitting by pyrolyzing a single-source precursor PtCl₆³⁻ guest-intercalated MgNiFe-layered double hydroxide (MgNiFe-LDH) host via a distinctive interlayer confinement. Consequently, Pt/Ni₃Fe/rGO demonstrates attractive overpotentials of 240 and 76 mV at 10 mA cm⁻² for the oxygen and hydrogen evolution reactions (OER and HER), respectively, outperforming those of its /Ni₃Fe/rGO counterpart. Moreover, the Pt/Ni₃Fe/rGO∥Pt/Ni₃Fe/rGO electrolyzer generates a current density of 10 mA cm⁻² at 1.55 V, with a retention of 92.4% after 50 h. Furthermore, the measured specific activity and low transfer resistance, as well as the density functional theory (DFT) calculations, indicate that the active Pt/Ni₃Fe in Pt/Ni₃Fe/rGO can optimize the adsorption/desorption of reaction intermediates and thus boost OER/HER kinetics, all of which lead to enhanced performance. The results demonstrate that such an interlayer confinement-based synthesis strategy can allow for the design of cost-effective precious nanodots as potential electrocatalysts.