Applying electrochemical nitrate reduction reaction (NO3RR) to produce ammonia offers a sustainable alternative to the energy-intensive Haber-Bosch process, which is crucial for clean energy and agricultural applications. While 2D MXenes hold great promise as electrocatalysts for NO3RR, their application for ammonia production remains underexplored. This study combines experimental and theoretical approaches to evaluate the catalytic performance of a series of MXenes with different central metal atoms for NO3RR. Among the materials studied (Ti3C2Tx, Ti3CNTx, Ti2CTx, V2CTx, Cr2CTx, Nb2CTx, and Ta2CTx), Ti3-based MXenes exhibit superior faradaic efficiency, ammonia yield rate, and stability. Density functional theory calculations offer further insights explaining the structure-activity-based observations. This research establishes a foundation for future studies aimed at leveraging MXenes for electrochemical nitrate reduction for green synthesis of ammonia.

• Klíčová slova
• 2D materials, catalysis, electrochemistry,
• Publikační typ
• časopisecké články MeSH

A hollow cathode discharge with a copper nickel cathode (Cu50Ni50) was operated in an Ar/H2/N2 gas mixture. Optical emission spectroscopy revealed the formation of NH radicals, which serve as precursors for NH3 formation. Ion mass spectrometry showed the formation of NH3 + and NH4 + ions indicating NH3 formation. Gas samples taken at the exhaust of the vacuum system were analyzed by Fourier transform infrared spectroscopy. Clear evidence for NH3 formation was obtained from these measurements.

• Publikační typ
• časopisecké články MeSH

Ammonia is one of the most widely produced chemicals worldwide, which is consumed in the fertilizer industry and is also considered an interesting alternative in energy storage. However, common ammonia production is energy-demanding and leads to high CO2 emissions. Thus, the development of alternative ammonia production methods based on available raw materials (air, for example) and renewable energy sources is highly demanding. In this work, we demonstrated the utilization of TiB2 nanostructures sandwiched between coupled plasmonic nanostructures (gold nanoparticles and gold grating) for photoelectrochemical (PEC) nitrogen reduction and selective ammonia production. The utilization of the coupled plasmon structure allows us to reach efficient sunlight capture with a subdiffraction concentration of light energy in the space, where the catalytically active TiB2 flakes were placed. As a result, PEC experiments performed at -0.2 V (vs. RHE) and simulated sunlight illumination give the 535.2 and 491.3 μg h-1 mgcat-1 ammonia yields, respectively, with the utilization of pure nitrogen and air as a nitrogen source. In addition, a number of control experiments confirm the key role of plasmon coupling in increasing the ammonia yield, the selectivity of ammonia production, and the durability of the proposed system. Finally, we have performed a series of numerical and quantum mechanical calculations to evaluate the plasmonic contribution to the activation of nitrogen on the TiB2 surface, indicating an increase in the catalytic activity under the plasmon-generated electric field.

• Publikační typ
• časopisecké články MeSH