Facile synthesis of ultrasmall amorphous PdP/rGO nanocatalysts for high-performance formic acid electrooxidation

Amorphous noble metal nanomaterials have been emerging as high-performance electrocatalysts due to their numerous coordination unsaturated sites and isotropic characteristics. Nevertheless, the synthesis of amorphous noble metals with small sizes and high surface areas remains a formidable challenge due to the lack of an effective preparation strategy. Herein, we report the successful synthesis of sub-3 nm amorphous palladium phosphide (a-PdP) nanoparticles decorated on reduced graphene oxide (rGO) via a facile one-pot liquid phase reduction process by using sodium hypophosphite as both reductant and phosphorus source. When evaluated as electrocatalysts for formic acid oxidation (FAOR), the resulting a-PdP/rGO composites exhibited a significant mass activity of 3.65 mA μg⁻¹, surpassing most previously reported Pd-based electrocatalysts. Moreover, the a-PdP/rGO composites exhibit a significant enhancement in electrochemical stability, maintaining 60 % of their initial activity after 1000 cycles, far exceeding rGO-supported pure crystalline Pd (c-Pd/rGO) (25 %) and the commercial Pd/C (22 %). Density functional theory (DFT) simulations confirm that the amorphous structure of PdP facilitates efficient C–H bond activation while mitigating CO poisoning effects. These synergistic properties accelerate reaction kinetics and improve the tolerance of a-PdP/rGO nanocatalysts, contributing to enhancing performance in FAOR.