Enhancing ethanol electrooxidation efficiency by co-modulating the electronic structure of Pd with B and Cu

The formidable challenge of CC bond cleavage during ethanol electrooxidation, coupled with the susceptibility of Pd-based catalysts to intermediate toxic species, poses a significant obstacle to the advancement of direct ethanol fuel cells. The present work reports a Graphene (GN)-supported Pd nanocatalyst co-modulated by B and Cu synthesized by a hydrothermal reduction method. The Pd₉₀Cu₁₀B/GN catalyst with optimized Pd/Cu ratio shows a high ethanol electrooxidation current density of 975 mA mg_Pd⁻¹, which is twice that of Pd/GN, and an excellent catalytic stability, which maintains 65.4 % of the highest current density after 1000 cycles. The remarkable catalytic performance of Pd₉₀Cu₁₀B/GN mainly stems from three aspects. First, B in the ternary alloy can adsorb more oxygen-containing species to oxidize the toxic species adsorbed on the adjacent Pd. Second, the electronic effect between Cu and Pd increases the d-band center of Pd, enhancing the adsorption ability of Pd to ethanol molecules and making them easier to be oxidized. Third, the appropriate ratio of Pd, Cu, and B, along with their interactions, results in an uniform and stable distribution of their alloy on GN, maximizing the exposure of active sites and allowing more ethanol molecules to be completely oxidized through an indirect pathway.