Bimetallic Phosphide-Sulfide Nanoparticles Embedded in S-Doped Three-Dimensional Porous Carbon as Efficient Electrocatalysts for OER

Abstract

Porous carbon has been extensively employed as a support for phosphide and sulfide nanoparticles to develop efficient and low-cost oxygen evolution reaction (OER) catalysts, owing to its superior electrical conductivity. This paper utilizes a cation exchange process in which the cations in the cation exchange resin (CER) are readily replaced by transition metal ions. Moreover, utilizing the inherent carbon-rich and sulfur-rich characteristics of CER, carbonization and phosphidation treatments were performed. The study successfully synthesizes a novel bimetallic phosphide-sulfide nanoparticle embedded in S-doped three-dimensional porous carbon electrocatalyst, NiCoPS@SC. The electrocatalyst exhibits exceptional catalytic performance in the OER: a low overpotential (329 mV) at 10 mA cm⁻² current density, a Tafel slope of 87.0 mV dec⁻¹, and a charge transfer resistance (2.47 Ω). The improved activity of NiCoPS@SC is attributed to the distinctive three-dimensional porous structure of the carbon nanomaterials and excellent electrical conductivity, which significantly increase the specific surface area (228.82 m² g⁻¹) and the density of active sites. Furthermore, the synergistic interaction between transition metal phosphide and sulfide nanoparticles, in conjunction with the strong integration with carbon nanostructures, improves interfacial interactions. This reduces metal particle agglomeration and erosion, thus enhancing catalytic performance while ensuring the structural stability and durability of the electrocatalyst. This three-dimensional porous transition bimetallic phosphide-sulfide carbon nanostructure offers a novel approach for developing practical transition metal OER catalysts.