Comprehensive analysis of catalysts, reaction mechanisms, and efficiency factors in photocatalytic nitrate-to-ammonia conversion

Varghese, Ajith P.; Lakhera, Sandeep Kumar

doi:10.1016/j.rser.2024.114537

Cited by 2 publications

(4 citation statements)

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“…A significant amount of nitrate contamination (132 Tg N yr −1 ) in surface and groundwater arises from the use of nitrogen-containing fertilizers in agriculture and emissions from industrial waste. 6,7 The presence of nitrates in drinking water can cause numerous health risks, such as blue baby syndrome, birth defects, and cancer. 8 The photocatalytic reduction of NO 3 − to NH 3 , powered by solar energy, presents a groundbreaking solution that addresses both environmental pollution and the rising demand for NH 3 .…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the hydrogen evolution reaction in aqueous media can divert energy from the desired NO 3 − to NH 3 conversion. 6 advanced photocatalysts with high activity and selectivity is essential to optimizing this promising approach for sustainable NH 3 production. In photocatalytic nitrate reduction reactions, the initial step involves destabilizing the nitrate by injecting an electron into its LUMO π* orbital, a process that demands substantial energy.…”

Section: Introductionmentioning

confidence: 99%

“…This has led to significant interest in photocatalytic nitrogen (N 2 ) fixation, which utilizes solar energy to convert abundant atmospheric N 2 into NH 3 . , Nevertheless, the process faces major challenges due to the high dissociation energy, limited aqueous solubility, and low proton affinity of N 2 molecules, resulting in low NH 3 yields. , Nitrate (NO 3 – ) offers a compelling alternative for ammonia production due to its lower dissociation energy (204 kJ/mol vs 941 kJ/mol of N 2 ), high water solubility, and strong proton affinity. A significant amount of nitrate contamination (132 Tg N yr –1 ) in surface and groundwater arises from the use of nitrogen-containing fertilizers in agriculture and emissions from industrial waste. , The presence of nitrates in drinking water can cause numerous health risks, such as blue baby syndrome, birth defects, and cancer . The photocatalytic reduction of NO 3 – to NH 3 , powered by solar energy, presents a groundbreaking solution that addresses both environmental pollution and the rising demand for NH 3 .…”

Section: Introductionmentioning

confidence: 99%

“…Despite its potential, the NO 3 – reduction pathway is complex, yielding various intermediates and end products such as N 2 , NO 2 – , N 2 H 4 , and NH 3 . Furthermore, the hydrogen evolution reaction in aqueous media can divert energy from the desired NO 3 – to NH 3 conversion . Thus, developing advanced photocatalysts with high activity and selectivity is essential to optimizing this promising approach for sustainable NH 3 production.…”

Section: Introductionmentioning

confidence: 99%

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Advancing the Understanding of Photocatalytic Nitrate Reduction for Ammonia Synthesis: Copper Catalysts and Formic Acid Synergy

Varghese,

T. P.,

Neppolian

et al. 2024

ACS Appl. Energy Mater.

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In recent years, photo-and electrocatalytic nitrate reductions have emerged as promising methods for sustainable ammonia production. Among the catalysts studied, copper-based systems have shown superior efficiency and selectivity in nitrate conversion, especially in the presence of sacrificial formic acid. However, the catalytic activity of copper is often hindered by its unstable oxidation state, primarily due to surface oxidation, and the underlying reaction mechanism remains poorly understood. This study reports that the scavenger formic acid plays a versatile role in the CuO x :TiO 2 catalytic system: first, it stabilizes the Cu 2 O phase on the TiO 2 surface. Second, it acts as a hole scavenger, reducing electron−hole recombination. Third, as formic acid undergoes oxidation, it produces CO 2•− radicals with significant reduction potential. These radicals effectively facilitate the reduction of nitrate ions, resulting in ammonia production. Moreover, copper's unique ability to degrade formic acid contributes to the creation of bound atomic hydrogen on its surface. This, in turn, promotes selective nitrate hydrogenation and subsequent formation of ammonia within the catalytic system. The CuO x :TiO 2 produced 1.639 mmol/g/h ammonia with an 82% nitrate-to-ammonia conversion rate. These findings not only deepen our comprehension of photocatalytic nitrate reduction processes but also highlight the potential of Cu:TiO 2 /Cu 2 O catalysts for sustainable ammonia production and environmental remediation applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%