Electrochemical conversion of nitrate to ammonia offers an efficient approach to reducing nitrate pollutants and a potential technology for low-temperature and low-pressure ammonia synthesis. However, the process is limited by multiple competing reactions and NO3− adsorption on cathode surfaces. Here, we report a Fe/Cu diatomic catalyst on holey nitrogen-doped graphene which exhibits high catalytic activities and selectivity for ammonia production. The catalyst enables a maximum ammonia Faradaic efficiency of 92.51% (−0.3 V(RHE)) and a high NH3 yield rate of 1.08 mmol h−1 mg−1 (at − 0.5 V(RHE)). Computational and theoretical analysis reveals that a relatively strong interaction between NO3− and Fe/Cu promotes the adsorption and discharge of NO3− anions. Nitrogen-oxygen bonds are also shown to be weakened due to the existence of hetero-atomic dual sites which lowers the overall reaction barriers. The dual-site and hetero-atom strategy in this work provides a flexible design for further catalyst development and expands the electrocatalytic techniques for nitrate reduction and ammonia synthesis.

Carbon-coated SiO 2 /TiO 2 (SiO 2 /TiO 2 @C) nanosheets consisting of TiO 2 nanoparticles uniformly embedded in SiO 2 matrix and a carbon-coating layer are fabricated by using acidified titanosilicate JDF-L1 nanosheets as template and precursor. SiO 2 /TiO 2 @C has unique structural features of sheetlike nanostructure, ultrafine TiO 2 nanoparticles distributed in SiO 2 matrix, and carbon coating, which can expedite ion diffusion and electron transfer and relieve volume expansion efficiently, and thus, the synergetic combination of these advantages significantly enhances its Li storage capability. As anode of lithium-ion batteries (LIBs), SiO 2 /TiO 2 @C nanosheets exhibit a high capacity of 998 mAh g −1 at 100 mA g −1 after 100 cycles. Moreover, an ultrahigh capacity of 410 mAh g −1 retains at 2000 mA g −1 after 400 cycles. A mixed reaction mechanism of capacitance and diffusioncontrolled intercalation is revealed by qualitative and quantitative analysis.