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

Sep 29, 2026

Efficient, sustainable ammonia production is crucial for global food security and energy sustainability. This study develops a defect-rich gas–solution (G–S) photocatalytic nitrogen reduction reaction system using molybdenum oxide deposited on carbon fiber paper (MoO3@CFP) and a low-cost 24 W plant lamp. The setup avoids nitrogen gas bubbling by using ambient air, leverages amorphous structure for active sites and defect centers, and reports a mass-normalized ammonia rate of 15.144 mmol·g−1·h−1 sustained across five cycles. Characterization confirms catalyst integrity, and a mechanism involving Mo–O–Mo linkages and defect sites is proposed.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages11

Reading Time28 min

AccessFree to download

Abstract

Introduction

Challenges in conventional systems

Strategies for photocatalytic nitrogen reduction

Defect engineering and interfacial charge transfer

Conclusions

This article is licensed under CC-BY 4.0 [http://pubs.acs.org/journal/acsodf](http://pubs.acs.org/journal/acsodf) Article Defect-Rich Gas−Solution Photocatalytic Systems for Nitrogen Reduction Reactions: Enabling Energy and Carbon Reductions Shih-Mao Peng, Muhammad Saukani, Jen-Chang Yang, and Tsung-Rong Kuo* Cite This: ACS Omega 2025, 10, 58821−58831 Read Online | | | | | | | | --- | --- | --- | --- | --- | --- | | ACCESS | Metrics & More | | Article Recommendations | | *sı Supporting Information | 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. 1. INTRODUCTION Ammonia (NH3) has garnered significant attention for its broad applications as a green fertilizer, carbon-free fuel, and efficient energy carrier, offering practical solutions to carbon neutrality and the intermittency of renewable energy. Its high energy density, carbon-free fuel, and established global supply chain make NH3 a leading candidate for zero-carbon fuels, particularly in heavy transportation, fuel cells, gas turbines, and marine engines.1,2 However, conventional ammonia synthesis via the Haber−Bosch process remains energy-intensive, as it requires high temperatures and pressures, which raises environmental and sustainability concerns.3,4 In contrast, renewable-energy-driven catalytic approaches for “green ammonia” production provide sustainable alternatives with immense potential for large-scale fossil fuel displacement.5−7 As energy systems worldwide advance toward decarbonization, the versatility and scalability of ammonia reinforce its pivotal role in shaping the future of sustainable energy.8,9 Catalytic ammonia synthesis methods include photocatalysis, 10, 11 electrocatalysis, 12, 13 and biocatalysis. 14−16 Among these, photocatalysis, inspired by natural photosynthesis, directly converts solar energy into chemical energy and has emerged as a promising strategy for photoreactions. This sunlight-driven approach not only eliminates the energy input required for electrocatalysis but also enables sustainable NH3 production using natural energy sources. Conventional photocatalysts, including metals (noble metals, 17−19 main group metals,20−24 and transition metals25−30), sulfides,31−35 and carbon-based structures,36−48 have been extensively studied for this reaction. However, their catalytic efficiency is often constrained by an insufficient number of active sites for binding and activating the strong N􀀁N triple bond (941 kJ mol−1) . Single-atom catalysts (SACs) offer a compelling alternative by increasing the availability of active sites and maximizing atomic efficiency. Despite these advantages, achieving precise control over the local chemical environment surr

FAQs

How does the gas–solution (G–S) system enable nitrogen reduction without nitrogen gas bubbling?

It uses ambient air as the nitrogen source in the gas–solution configuration, removing the need for bubbling nitrogen gas through the reaction medium.

What catalyst design features improve nitrogen activation in MoO3@CFP?

The amorphous MoO3@CFP structure provides abundant active sites and defect centers that facilitate nitrogen activation and electron transfer.

What performance and stability results are reported under optimized conditions?

With optimized parameters (current 0.25 A, deposition time 600 s, stirred), the system achieves 15.144 mmol·g−1·h−1 ammonia production and maintains performance over five consecutive 1-hour cycles, with characterization confirming structural and compositional stability.

Sep 29, 2026

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