Manipulating electron redistribution in platinum for enhanced alkaline water splitting kinetics

Abstract

The potential of hydrogen production via water splitting technology makes it urgent to develop low-cost and highly active bifunctional catalysts for hydrogen and oxygen evolution reactions (HER/OER). In this study, a low platinum (Pt) bimetallic phosphide heterostructure (Pt-NiFe-P/NF), derived from three-dimensional NiFe metal–organic framework (NiFe-MOF) nanorods on nickel foam (NF), was developed using a two-step hydrothermal and phosphorization process. The nickel-iron phosphide nanorod array heterostructure boasts a large surface area with numerous active sites, which enhances charge and substance transfer. The integration of metallic Pt with NiFe-P heterostructures subtly adjusts the electronic redistribution between them, thereby improving the kinetics of water splitting. Consequently, the Pt-NiFe-P/NF catalyst demonstrated exceptional HER and OER performance in a 1 M KOH solution, with overpotentials of 97 and 266 mV at 100 mA cm⁻², respectively. Remarkably, an electrolyzer utilizing this catalyst requires just a 1.65 V potential to achieve a current density of 100 mA cm⁻², exceeding the capabilities of conventional Pt/C||RuO₂ systems, which require 2.10 V and outperforming many advanced electrochemical water splitting catalysts currently in use.