Tuning Morphologies of Metal-Organic Framework-Derived Ni₃P/Ni Carbon Nanocomposites for Water Oxidation

The oxygen evolution reaction (OER) frequently acts as a kinetic bottleneck in various energy storage and conversion systems. Effective electrocatalysts for the OER play a crucial role in reducing the reaction barrier and expediting the reaction. Multicomponent transition metal phosphides (TMPs) have garnered an extensive amount of attention as a result of their exceptional performance in the OER. Here, we present a direct method for preparing two intrinsic morphologies of metal-organic frameworks (MOFs), barrel-like BMM-10 and pancake-like BMM-10(Ac), achieved by establishing a protonation/deprotonation equilibrium with varying NO₃^-/Ac^- ratios. The BMM-10(Ac)-C catalyst was synthesized via heat treatment of the BMM-10(Ac) precursor, exhibiting superior OER performance. It realized an overpotential of 286 mV at a current density of 10 mA cm^-2, with a Tafel slope of 111.17 mV decade^-1 and a current retention of 98.03%. This improvement arises from the synergistic interaction between Ni₃P/Ni nanoparticles and the partially graphitic carbon layer, augmenting the exposure of active sites. Furthermore, alterations in the morphological features of MOF-derived Ni₃P/Ni carbon nanocomposites adjusted the active electrochemical surface area, thereby modulating the overall OER performance of the corresponding TMP carbon nanocomposites. This methodology can be extended to control the morphology of other MOFs and their derivatives, providing innovative avenues for the design and synthesis of new MOF-based TMP nanomaterials.