Tong Miaomiao, Yu Peng, Xie Ying, Wang Lei, Wang Ying, Fu Honggang
Key Laboratory of Superlight Materials and Surface Technology of the Ministry of Education of the People's Republic of China, Harbin Engineering University, Harbin, 150080, China.
Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin, 150025, China.
Small. 2022 Jun;18(22):e2201255. doi: 10.1002/smll.202201255. Epub 2022 May 7.
Introducing heteroatoms into atomically dispersed Fe-N sites with symmetric electron distribution can adjust the imperfect oxygenated adsorption-activation and promote oxygen reduction reaction (ORR) activity. However, the relevant design synthesis and deeply understanding the electrocatalytic mechanism of such an asymmetric structure by introducing Fe-C coordination remains challenging. Herein, the structural stability of Fe-N C (x = 0 ≈ 4, y = 4-x) is first theoretically predicted and indicates that the energy of Fe-N in the two most stable structures is greater than that of Fe-N C. Subsequently, Fe-N and Fe-N C configurations are controlled synthesized by adjusting pyrolytic temperature. The Fe-N C-based electrocatalyst displays a boosted ORR activity with a half-wave potential of 0.91 V and superior long-term stability, outperforming Fe-N , Pt/C, and state-of-the-art noble metal-free electrocatalysts. Density functional theory calculations unveil that Fe-N C is much more favorable for electron delocalization than Fe-N . Furthermore, the residual Zn atom derived from ZIF-8 would give its d-orbit electron to the Fe atom, so the synergy between Fe-N C and Zn-N makes an enhanced ORR activity.
将杂原子引入具有对称电子分布的原子分散的Fe-N位点可以调节不完善的氧吸附活化，并促进氧还原反应（ORR）活性。然而，通过引入Fe-C配位来设计合成这种不对称结构并深入理解其电催化机理仍然具有挑战性。在此，首先从理论上预测了Fe-N C（x = 0≈4，y = 4-x）的结构稳定性，结果表明，在两种最稳定的结构中，Fe-N的能量高于Fe-N C。随后，通过调节热解温度来控制合成Fe-N和Fe-N C构型。基于Fe-N C的电催化剂表现出增强的ORR活性，半波电位为0.91 V，具有优异的长期稳定性，优于Fe-N、Pt/C和目前最先进的无贵金属电催化剂。密度泛函理论计算表明，Fe-N C比Fe-N更有利于电子离域。此外，源自ZIF-8的残留Zn原子会将其d轨道电子给予Fe原子，因此Fe-N C和Zn-N之间的协同作用增强了ORR活性。
