Efficient photocatalytic nitrogen fixation from air under sunlight via iron-doped WO$_3$

TL;DR

This study presents a Fe-doped WO$_3$ photocatalyst that efficiently fixes nitrogen from air under sunlight, offering a promising, cost-effective alternative to industrial processes for sustainable ammonia production.

Contribution

Development of a Fe-doped layered WO$_3$ photocatalyst with oxygen vacancies that significantly enhances nitrogen fixation efficiency under sunlight.

Findings

Photocatalytic efficiency is about 4 times higher than pure WO$_3$.

Nitrogen fixation rate reaches up to 477 μg·g$_{cat}^{-1}$·h$^{-1}$ under sunlight.

Infrared detection confirms the nitrogen fixation process.

Abstract

Photocatalytic nitrogen fixation from air directly under sunlight can contribute significantly to carbon neutralization. It is an ideal pathway to replace the industrial Haber Bosch process in future. A Fe-doped layered WO$_3$ photocatalyst containing oxygen vacancies was developed which can fix nitrogen from air directly under sunlight at atmospheric pressure. The iron doping enhances the transport efficiency of photogenerated electrons. The photocatalytic efficiency is around 4 times higher than that of pure WO$_3$. The optimum nitrogen fixation conditions were examined by orthogonal experiments and its nitrogen fixation performance could reach up to 477 $\mu \text{g} \cdot \text{g}_{\text{cat}}^{-1} \cdot \text{h}^{-1}$ under sunlight. In addition, the process of nitrogen fixation was detected by situ infrared, which confirmed the reliability of nitrogen fixation. Also, modelling on the interactions between light and the photocatalyst was carried out to study the distribution of surface charge and validate the light absorption of the photocatalyst. This work provides a simple and cheap strategy for photocatalytic nitrogen fixation from air under mild conditions.