State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, China.
Nat Commun. 2017 Jan 10;8:14136. doi: 10.1038/ncomms14136.
Incorporating oxophilic metals into noble metal-based catalysts represents an emerging strategy to improve the catalytic performance of electrocatalysts in fuel cells. However, effects of the distance between the noble metal and oxophilic metal active sites on the catalytic performance have rarely been investigated. Herein, we report on ultrasmall (∼5 nm) Pd-Ni-P ternary nanoparticles for ethanol electrooxidation. The activity is improved up to 4.95 A per mg, which is 6.88 times higher than commercial Pd/C (0.72 A per mg), by shortening the distance between Pd and Ni active sites, achieved through shape transformation from Pd/Ni-P heterodimers into Pd-Ni-P nanoparticles and tuning the Ni/Pd atomic ratio to 1:1. Density functional theory calculations reveal that the improved activity and stability stems from the promoted production of free OH radicals (on Ni active sites) which facilitate the oxidative removal of carbonaceous poison and combination with CHCO radicals on adjacent Pd active sites.
将亲氧金属纳入贵金属基催化剂中是提高燃料电池中电催化剂催化性能的一种新兴策略。然而，贵金属和亲氧金属活性位之间的距离对催化性能的影响很少被研究。在此，我们报道了用于乙醇电氧化的超小（约 5nm）Pd-Ni-P 三元纳米颗粒。通过将 Pd 和 Ni 活性位之间的距离缩短，实现了 Pd/Ni-P 杂二聚体到 Pd-Ni-P 纳米颗粒的形状转变，并将 Ni/Pd 原子比调至 1:1，活性提高到 4.95 A/mg，是商业 Pd/C（0.72 A/mg）的 6.88 倍。密度泛函理论计算表明，活性和稳定性的提高源于促进了游离 OH 自由基的生成（在 Ni 活性位上），这有利于去除碳质毒物和与相邻 Pd 活性位上的 CHCO 自由基结合。
