# Defect-Rich Gas–Solution Photocatalytic Systems for Nitrogen Reduction Reactions: Enabling Energy and Carbon Reductions

## TL;DR

This study introduces a new photocatalytic system that uses ambient air to produce ammonia efficiently and sustainably.

## Contribution

A novel gas–solution photocatalytic system using MoO3@CFP and ambient air for ammonia production is developed.

## Key findings

- The system achieved a high ammonia production rate of 15.144 mmol·g–1·h–1 under optimized conditions.
- The catalyst maintained performance over five consecutive cycles, showing structural and compositional stability.
- Defect sites and Mo–O–Mo linkages were identified as key to electron transfer and nitrogen activation.

## Abstract

The efficient and sustainable production of ammonia is
pivotal
for global food security and energy sustainability. In this study,
we developed a novel gas–solution (G–S) photocatalytic
nitrogen reduction reaction (PNRR) system utilizing molybdenum oxide
deposited onto carbon fiber paper (MoO3@CFP) and a low-cost
24 W plant lamp as the illumination source. The G–S system
eliminates the need for nitrogen gas bubbling by relying on ambient
air as the nitrogen source and was demonstrated to be a simplified
and scalable approach to ammonia production. The amorphous structure
of MoO3@CFP provides abundant active sites and defect centers,
enabling effective nitrogen activation and reduction. Under optimized
conditions (current = 0.25 A, deposition time = 600 s, stirred), the
system achieved a mass-normalized ammonia production rate of 15.144
mmol·g–1·h–1 and sustained
performance over five consecutive cycles (1 h per cycle). Material
characterization confirmed the structural integrity and compositional
stability of the catalyst after repeated use. A working mechanism
is proposed in which Mo–O–Mo linkages and defect sites
facilitate electron transfer and nitrogen activation. Overall, this
study introduces a cost-effective route to photocatalytic ammonia
synthesis using ambient air in a G–S configuration.