Related Experiment Video
Updated: Jun 17, 2026
10:15
Solar-Driven Electrochemical Green Fuel Production from CO2 and Water Using Ti3C2Tx MXene-Supported CuZn and NiCo Catalysts
Published on: November 7, 2025
Photoelectrocatalytic NOx Reduction to Ammonia: Advances and Challenges
Laura Collado1, Víctor A de la Peña O'Shea2, Miguel García-Tecedor2
1Instituto de Catálisis y Petroleoquímica (ICP), CSIC, C/Marie Curie 2, 28049 Madrid, Spain.
ACS Applied Materials & Interfaces
|June 16, 2026
Summary
Photoelectrochemical reduction of nitrogen oxides (NOxRR) offers a sustainable route to produce ammonia (NH3) using solar energy. This review highlights advancements in photocathode design and mechanistic understanding for efficient, carbon-neutral ammonia synthesis.
Area of Science:
- Materials Science and Engineering
- Electrochemistry
- Renewable Energy Technologies
Background:
- Conventional ammonia synthesis (Haber-Bosch) is energy-intensive and carbon-emissive.
- Photoelectrochemical (PEC) NOx reduction (NOxRR) presents a sustainable alternative for ammonia production.
- NOxRR utilizes solar energy to convert nitrogenous pollutants into ammonia under ambient conditions.
Purpose of the Study:
- To review recent progress in PEC NOxRR for sustainable ammonia synthesis.
- To emphasize interfacial engineering strategies for photocathode design.
- To provide mechanistic insights into multielectron, proton-coupled reduction pathways.
Main Methods:
- Analysis of fundamental electrochemical and photophysical principles of NOxRR.
- Discussion of recent developments in photocathode materials (e.g., copper oxides, bismuth vanadate, titania).
- Comparison of pure PEC and photovoltaic-electrochemical coupled systems for solar-driven NOx reduction.
Main Results:
- Recent advancements in photocathode materials and hybrid architectures enhance activity and selectivity.
- Integration of molecular catalysts, plasmonic components, and cocatalysts improves PEC NOxRR performance.
- Both pure PEC and coupled photovoltaic-electrochemical systems show promise for solar-driven ammonia production.
Conclusions:
- PEC NOxRR is a promising pathway for decentralized and carbon-neutral ammonia production.
- Addressing challenges like photocorrosion, product quantification, and scalability is crucial for future development.
- Integrated approaches in materials design, interfacial catalysis, and device engineering are key to realizing efficient solar-driven ammonia synthesis.
Related Concept Videos
02:10Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia
Alkynes can be reduced to trans-alkenes using sodium or lithium in liquid ammonia. The reaction, known as dissolving metal reduction, proceeds with an anti addition of hydrogen across the carbon–carbon triple bond to form the trans product. Since ammonia exists as a gas (bp = −33°C) at room temperature, the reaction is carried out at low temperatures using a mixture of dry ice (sublimes at −78°C) and acetone.
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
01:29Preparation of Amines: Reduction of Oximes and Nitro Compounds
Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
01:38Preparation of Amines: Reductive Amination of Aldehydes and Ketones
Carbonyl compounds and primary amines undergo reductive amination first to produce imines, followed by secondary amines in the same reaction mixture, using selective reducing agents like sodium cyanoborohydride or sodium triacetoxyborohydride. Reductive amination produces different degrees of substitution of amines depending on the starting amine substrate.
01:13Preparation of Amines: Reduction of Amides and Nitriles
Nitriles can be reduced to primary amines using reducing agents like lithium aluminum hydride or catalytic hydrogenation. The reduction introduces an amino group with an extra carbon in the skeleton. Nitriles are formed from the reaction between alkyl halides and sodium cyanide through the SN2 mechanism. Primary alkyl halides are the preferred substrates to prepare nitriles.
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
00:55Nitriles to Amines: LiAlH4 Reduction
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.