Ni²⁺ Tailoring Pd Enables Nanonet-Structured Catalysts with Dual Doping of H and Ni for Enhanced Alcohol Oxidation

Abstract

Ethanol oxidation reaction (EOR) is a crucial process in direct ethanol fuel cells. Although Pd exhibits potential as a substitute for Pt in EOR, its development is still hampered by its inferior activity due to its limited ability to break C−C bonds and the poisoning by strongly adsorbed intermediates. Herein, a one-step method for the preparation of NiPdH network nanomaterials (NiPdH NNs) was proposed with ethylene glycol (EG) as a H source. We explored the influence of preparation parameters on NiPdH NNs and examined the versatility of doping Pd with multiple metals and H in a one-step preparation method. These results demonstrated that urea can significantly influence the morphology of the samples. Additionally, the addition of metal sources had a crucial impact on the insertion of H. The doping of H and Ni can modify the electronic structure of Pd and might further modulate the adsorption strength of the reaction intermediates on the catalyst surface. Compared with PdNi nanoparticles without H atoms, NiPdH nanoparticles, and commercial Pd/C, NiPdH NN catalysts possessed the largest electrochemical active surface area and the smallest charge transfer resistance. Consequently, NiPdH NNs presented a strong resistance to CO poisoning, superior mass activities and catalytic stabilities in ethanol, methanol, and EG oxidation reactions. The significant enhancement in performance can be attributed to several factors. First, the oxyphilic metal Ni can promote the generation of OH* and accelerate the removal of CO. Second, the doping of H and Ni effectively regulates the electronic structure of Pd, optimizing the adsorption behaviors of reaction intermediates. Lastly, the network structure provides an abundance of catalytic active sites, promoting efficient mass transfer and overall reaction kinetics. This study offers valuable insights for the preparation of Pd-based hydrides with specific structures.