Promoting electrocatalytic nitrogen reduction to ammonia via Fe-boosted nitrogen activation on MnO2 surfaces†
The electrocatalytic nitrogen (N2) reduction reaction is recognized as a green and sustainable approach for ammonia (NH3) synthesis alternative to the traditional industrial method – the Haber–Bosch process, while an efficient electrocatalysis of such a process is a prerequisite for N2 reduction. Developing a cost-effective electrocatalyst for the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions with an excellent catalytic performance remains a great challenge. Here, we report a facile hydrothermal reaction to synthesize Fe-doped manganese oxide (MnO2) with a nanoneedle morphology as a cost-effective electrocatalyst for the NRR. It is verified that Fe plays a critical role in the NRR. This catalyst shows an excellent catalytic performance with a high faradaic efficiency of 16.8% and a high NH3 formation rate of 39.2 μg h−1 mgcat.−1 at −0.29 V vs. the reversible hydrogen electrode in 0.1 M Na2SO4, which are much higher than those of all reported Mn-based NRR catalysts and many other previously reported catalysts. This catalyst also shows excellent durability during electrolysis and recycling tests. In addition, the electrocatalyst mechanism is also assessed in combination with density functional theory.