Mechanically Bending Centrosymmetric Nano-CeO2 for Flexoelectric N2 Fixation from Air.

Nitrogen fixation is vital for ecological balance and agricultural production, whereas the classic Haber-Bosch synthetic ammonia route is energy-intensive and environmentally detrimental. Mechanical energy is ubiquitous in nature, making its utilization for nitrogen fixation highly attractive. Flexoelectric materials can convert mechanical energy to electric energy under the excitation of mechanical strain gradients, yielding the novel catalysis technology flexocatalysis. Flexocatalysis can occur almost in all catalysts. In this work, nano-CeO2 with abundant oxygen vacancies are used as a flexocatalyst realized direct nitrogen fixation from air under vibration. The maximum NH4+ production rate reaches 181.24 μmol g-1 h-1, which is 17.9 times that of the catalyst-free control. Density functional theory (DFT) analysis confirms that in-plane anisotropy-induced lattice distortion provides direct evidence for the flexoelectricity of CeO2. This work holds potential value for future applications of ambient mechanical vibration energy in flexocatalysis for direct nitrogen fixation from air.