Adsorbing and Activating N2 on Heterogeneous Au–Fe3O4 Nanoparticles for N2 Fixation

• Published in: Advanced functional materials Vol. 30; no. 4
• Main Authors: Zhang, Jin, Ji, Yujin, Wang, Pengtang, Shao, Qi, Li, Youyong, Huang, Xiaoqing
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.01.2020
• Subjects: Adsorption; Ammonia; Charge transfer; Chemical reduction; Fe3O4; Gold; heterostructure; Iron oxides; Materials science; N2 reduction; Nanoparticles; Nitrogenation; Photoelectrons; Spectrum analysis; Surface chemistry; Surface structure; Synergistic effect
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201906579

Electrochemical nitrogen reduction reaction (NRR) is a promising approach to convert earth‐adundant N2 into highly value‐added NH3. Herein, it is demonstrated that the heterogeneous Au–Fe3O4 nanoparticles (NPs) can be adopted as highly efficient catalysts for NRR. Due to the synergistic effect of the strong N2 fixation ability of Fe3O4 and the charge transfer capability of Au, the Au–Fe3O4 NPs show excellent performance with a high yield (NH3: 21.42 µg mgcat−1 h−1) and a favorable faradaic efficiency (NH3: 10.54%) at −0.2 V (vs reversible hydrogen electrode), both of which are much better than those of the Au NPs, Fe3O4 NPs, as well as core@shell Au@Fe3O4 NPs. It also exhibits good stability with largely maintained performance after six cycles. The N2 temperature‐programmed desorption, surface valance band spectra, and X‐ray photoelectron spectroscopy collectively confirm that Au–Fe3O4 NPs have a strong adsorption capacity for the reaction species and suitable surface structure for electronic transfer. The theoretical calculations reveal that Fe provides the active site to fix N2 into *N2H while introducing Au optimizes the adsorption of NRR intermediates, making the NRR pathway on Au–Fe3O4 along an energetic‐favorable process and enhancing the NRR. Au–Fe3O4 heterogeneous nanoparticles (NPs) and Au@Fe3O4 core/shell NPs are selectively prepared and directly adopted as ideal model electrocatalysts to evaluate N2 electroreduction for the first time, where the Au–Fe3O4 heterogeneous NPs have a unique synergistic effect between the high electrochemical performance of Au and the strong N2 fixation capacity of Fe3O4, resulting in enhanced nitrogen reduction reaction activity.