Ternary PdCoNi flower-like ultrathin nanosheet assembly with efficient electrocatalytic performance for formic acid oxidation

The development of high activity, high stability and low cost anode catalysts is a key challenge for the commercialization of direct formic acid fuel cells. The ternary Pd-based alloy catalyst has been proved to be an effective catalyst for formic acid electrooxidation. Herein, PdCoNi ternary alloy catalyst with flower-like ultrathin nanosheet structure are fabricated to serve as a robust electrocatalyst for formic acid oxidation reaction (FAOR) by a simple two-step wet chemical method. Surpassing binary PdCo Ns, PdNi Ns and Pd/C catalysts, the as-prepared PdCoNi Ns achieve extremely high catalytic activity of formic acid oxidation (3221.2 mA·mg⁻¹_Pd), with a mass activity 2.6 times that of PdCo Ns, 2.3 times that of PdNi Ns, and 6.3 times that of Pd/C. After undergoing 1000 cycles of aging tests, the peak current density of PdCoNi Ns catalyst remains at around 65.8%, far superior to Pd/C catalysts, demonstrating substantially improved stability. The improvement of electrocatalytic performance depends on the introduction of Co and Ni atoms, which can effectively modify electronic structure of Pd, increase the available active sites, accelerate charge transfer rate as well as promote mass transport by ultrathin nanosheet structure. Hence, PdCoNi Ns possesses a promising future as a fuel cell electrocatalyst.