Ammonia (NH 3 ) is traditionally produced through the energy-intensive Haber-Bosch process which converts nitrogen (N 2 ) and hydrogen (H 2 ) into NH 3 at high temperatures (400−500 ℃) and pressures (10−30 MPa). This process consumes 1-2% of global energy and contributes about 1% of global CO 2 emission.
Electrocatalytic nitrate reduction reaction (NO 3 − RR) is a renewable energy-driven process that uses nitrate (NO 3 − ) from wastewater as N 2 source and water as H 2 source. This low-carbon route provides a sustainable solution for NH 3 synthesis under mild conditions. However, its practical application has been limited by unsatisfactory electrocatalytic activity and poor long-term stability.
A research team led by Prof. GAO Dunfeng, Prof. WANG Guoxiong, and Prof. BAO Xinhe from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), by introducing an amorphous/crystalline dual-phase Cu foam electrode with high performance, achieved high-rate and stable NH 3 electrosynthesis from NO 3 − . The study was published in Nature Communications .
Researchers fabricated the electrode by thermal annealing commercial Cu foam in air, creating a unique dual-phase structure. With an alkaline membrane electrode assembly electrolyzer, they achieved an NH 3 partial current density of 3.33 A/cm 2 and an NH 3 formation rate of 15.5 mmol/h/cm 2 at a cell voltage of just 2.6 V. The electrode maintained stable NH 3 production with a Faradaic efficiency of around 90% at an applied current density of 1.5 A/cm 2 over 300 hours.
Furthermore, researchers identified that the stable amorphous Cu domains present during the reaction are key to the outstanding catalytic performance. This integrated Cu foam electrode performs better than conventional power electrodes, and the preparation protocols are facile and easy to scale up. In a scale-up demonstration using a 100 cm 2 electrode, an NH 3 formation rate of up to 11.9 g/h at an applied current of 160 A was achieved.
"Our work also underscores the importance of stabilizing metastable amorphous structures for improving electrocatalytic reactivity and long-term stability," said Prof. WANG.
Nature Communications
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21-Feb-2025