介孔钯-硼合金纳米颗粒的制备和甲醇氧化电催化性能北大核心CSCD

合金化可以调节贵金属纳米材料的物理化学性质,从而显著提升它们的电催化性能。尽管合金化在过去的20多年里已取得诸多成果,但是如何充分发挥纳米合金的组分优势仍需深入的探究。本研究通过一步溶液相合成法实现了类金属硼(B)合金化的钯基介孔纳米催化剂材料的合成,同时探究了B原子的组分优势和介孔形貌的结构优势在碱性介质中电化学甲醇氧化反应(MOR)的协同作用。最优PdCuB介孔纳米催化剂表现出优异的电化学MOR活性和稳定性。机理研究表明,优异的催化活性源于B原子在Pd基介孔纳米催化剂中的积极协同作用;该协同作用通过电子效应(改变Pd的表面电子结构从而减弱CO基中间体的吸附)和双功能效应(促进OH_(2)的吸附从而氧化CO基中间体)在动力学上加速了有毒CO基中间体的去除(提高甲醇氧化的决速步骤)。同时,B原子的间隙插入和介孔结构抑制了物理奥斯特瓦尔德(Ostwald)熟化过程,显著增加了催化剂的稳定性。

Mesoporous Palladium⁃Boron Alloy Nanocatalysts： Synthesis and Performance in Methanol Oxidation Electrocatalysis

Alloying is able to adjust physical and chemical properties of noble metal-based nanocatalysts， thus significantly improving their electrocatalytic performance. Although alloying has made many achievements in the past two decades， it still needs in-depth research and understanding to make full use of the advantages of nano-alloys. In this study， we reported a one-step solution-phase synthesis method to co-alloy metalloid boron （B） in palladium-based mesoporous nanocatalysts and further demonstrated their high electrochemical methanol oxidation reaction （MOR） performance in alkaline media. The best PdCuB mesoporous nanocatalyst shows excellent electrochemical MOR activity （2.48 A mg_Pd^-1） and stability. The catalytic mechanism studies shows that B atom not only changes the electronic structure of Pd sites which directly weakens the adsorption strength of CO-based intermediates but also promotes the adsorption of OH^－ which optimizes the oxidation of CO-based intermediates （the rete-determining step）. Such a synergy remarkably improves the MOR kinetics and enhances its catalytic performance accordingly. Meanwhile， interstitially inserting metallic B atoms and structural mesoporosity also inhibites the physical Ostwald ripening process and thus stabilizes the catalyst.