Data_Sheet_1_Bimetallic Metal-Organic Framework Derived Metal-Carbon Hybrid for Efficient Reversible Oxygen Electrocatalysis.PDF

Development of cost-effective electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is key to enabling advanced electrochemical energy conversion technologies. Here, a novel nitrogen-doped metal-carbon hybrid (NiCo/CN) with a unique 3D hierarchical structure, consisting of uniformly distributed bimetallic nanoparticles encapsulated by partially graphitized N-doped carbon shells, is fabricated by a one-step pyrolysis of a nanoscale metal-organic framework as precursor, which exhibits excellent activity for both ORR and OER. The surface chemical changes on the carbon hybrid probed by X-ray photoelectron spectroscopy (XPS) reveal the presence of favorable electronic interaction at the metal-nitrogen-carbon interface. Remarkably, the NiCo/CN catalyst prepared at high temperature (800°C) manifests a comparable performance to a commercial Pt/C catalyst for the ORR, but also superior stability, path selectivity and methanol tolerance. On the other hand, the Eonset (1.48 V vs. reversible hydrogen electrode) and Ej=10mA/cm2 of NiCo/CN-800 for OER is very close to the state-of-the-art noble catalyst RuO2 (Eonset = 1.46 and Ej=10mA/cm2) along with superior stability over 20 h of operation. The excellent catalytic property is attributable to the unique nanostructure, high porosity and the constructive synergistic effects of the elements M, N, and C.

开发适用于氧还原反应（oxygen reduction reaction, ORR）与氧析出反应（oxygen evolution reaction, OER）的高性价比电催化剂，是实现先进电化学能源转换技术的核心关键。本研究以纳米级金属有机框架为前驱体，通过一步热解法制备得到一种具有独特三维分级结构的新型氮掺杂双金属碳复合材料（NiCo/CN）：该材料由均匀分散的双金属纳米颗粒被部分石墨化的氮掺杂碳壳包覆而成，对ORR与OER均表现出优异的催化活性。
通过X射线光电子能谱（X-ray photoelectron spectroscopy, XPS）对该碳复合材料的表面化学变化进行表征，结果揭示了金属-氮-碳界面处存在有利的电子相互作用。值得注意的是，在800℃高温下制备得到的NiCo/CN催化剂，其ORR催化性能可与商用Pt/C催化剂相媲美，同时具备更优异的稳定性、反应路径选择性与甲醇耐受性。
另一方面，NiCo/CN-800用于OER催化时，其起始电位（Eonset，1.48 V vs. 可逆氢电极）与电流密度达10 mA/cm²时的电位（Ej=10mA/cm²）与当前主流贵金属催化剂二氧化钌（RuO2）的对应参数（Eonset=1.46 V，Ej=10mA/cm²）极为接近，且在20小时持续运行中展现出更优的稳定性。
该复合材料的优异催化性能，可归因于其独特的纳米结构、高孔隙率以及金属（M）、氮（N）与碳（C）三种元素间的协同增效作用。