Confining intermediates within a catalytic nanoreactor facilitates nitrate-to-ammonia electrosynthesis

Electrocatalytic nitrate reduction reaction (NitRR) has gained attention because of its potential to mitigate environmental nitrogen pollution and recycle artificial nutrients. NitRR produces ammonia through complicated pathways that involve multistep electron transfer, while the formation of byproducts, e.g. toxic nitrite (NO2-), leads to lower energy efficiency and recontamination. In this work, we report the incorporation of CuOx active species into a TiO2-nanotube reactor (TiO2 NTs/CuOx) for the highly selective NitRR. In particular, the NO2- intermediate is diminished due to the hindered diffusion within the nanoconfined space. Thus, the CuOx modified nanoreactor performs a maximum faradaic efficiency of 92.23% and a yield rate of 1241.81 mu g h(-1) cm(-2) for nitrate-to-ammonia conversion. Theoretical insights further support a fundamental understanding of a cross scale interaction over the surface and interface. The findings suggest a promising approach for enhancing reaction activity and selectivity enabled by rationally designed active sites coupled with geometrically regulated structures.

Automated summary

This work demonstrates the incorporation of CuOx active species into a TiO2 nanotube reactor for selective electrocatalytic nitrate reduction reactions. The diffusion of the intermediate NO2- is hindered due to the nanoconfined space, leading to a high faradaic efficiency and conversion rate of nitrate to ammonia. Theoretical insights further support the understanding of the surface and interface interactions.