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Thermo–Electrochemical Coupled Proton Relay Unlocks Efficient Nitrate-to-Ammonia Conversion on Metal-Free Catalysts in Neutral Electrolytes
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AI
G
杨
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B
M
高
H
DOI：10.1002/adfm.77625.png)
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Abstract
En 中文
Electrochemical nitrate reduction to ammonia (NitRR) represents a promising strategy for sustainable ammonia production. However, efficient operation in neutral electrolytes remains challenging because proton-coupled electron transfer is kinetically limited by the slow water-dissociation-mediated proton transfer process. Here we report a thermally activated interfacial proton-transfer mechanism that enables efficient neutral NitRR on a metal-free sulfonated carbon nitride catalyst (NC─SO3). DFT calculations reveal that electrochemical protonation of surface sulfonate groups transiently generates ─SO3H intermediates, which act as local proton donors during electrocatalysis. Subsequent thermally enhanced proton transfer from these transient ─SO3H intermediates to nitrate intermediates adsorbed on neighboring graphitic nitrogen sites accelerates the hydrogenation steps without altering the adsorption centers of the NitRR pathway. This thermally-electrochemically coupled process becomes increasingly effective at elevated temperatures. At 80°C, the catalyst exhibits activity surpassing state-of-the-art nitrate reduction systems reported for both neutral and alkaline electrolytes. The mechanism is validated by the loss of thermal enhancement in alkaline electrolytes, where transient ─SO3H intermediates cannot be regenerated because the surface remains predominantly in the deprotonated ─SO3 state. These results demonstrate that thermo-electrochemically coupled proton relays provide an effective strategy to overcome proton-transfer limitations in neutral electrolyts and enable efficient nitrate-to-ammonia conversion under practically relevant conditions.
Keywords:
interfacial engineering
metal-free catalysts
neutral electrolytes
nitrate reduction reaction
proton relay
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19
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3.4W
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32.1W
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