High-Performance N₂-to-NH₃ Conversion Electrocatalyzed by Mo₂C Nanorod

Abstract

The synthesis of NH3 is mainly dominated by the traditional energy-consuming Haber–Bosch process with a mass of CO2 emission. Electrochemical conversion of N2 to NH3 emerges as a carbon-free process for the sustainable artificial N2 reduction reaction (NRR), but requires an efficient and stable electrocatalyst. Here, we report that the Mo2C nanorod serves as an excellent NRR electrocatalyst for artificial N2 fixation to NH3 with strong durability and acceptable selectivity under ambient conditions. Such a catalyst shows a high Faradaic efficiency of 8.13% and NH3 yield of 95.1 μg h–1 mg–1cat at −0.3 V in 0.1 M HCl, surpassing the majority of reported electrochemical conversion NRR catalysts. Density functional theory calculation was carried out to gain further insight into the catalytic mechanism involved.

Recent Advanced Materials for Electrochemical and Photoelectrochemical Synthesis of Ammonia from Dinitrogen: One Step Closer to a Sustainable Energy Future

“…In 2018, the Mo 2 N nanorods developed by Ren et al achieved an FE of 4.5% and a very high NH 3 yield of 78.4 µg mg −1 cat h −1 at −0.3 V versus RHE, benefiting from the decreased free energy barrier of the NRR determining step after nitrogenization of the MoO 2 precursor, although the source of nitrogen for ammonia production became ambiguous . In 2019, Mo 2 C nanorod was reported to achieve an NH 3 yield of 95.1 µg mg −1 cat h −1 and FE of 8.13% at −0.3 V versus RHE . Similarly, Xiang et al fabricated Fe 2 O 3 nanorods capable of catalyzing NRR with an FE of 0.94% and NH 3 yield of 15.9 µg mg −1 cat h −1 in neutral 0.1 m Na 2 SO 4 .…”

High‐Performance Electrocatalytic Conversion of N2 to NH3 Using Oxygen‐Vacancy‐Rich TiO2 In Situ Grown on Ti3C2Tx MXene

“…The average NH 3 yields and the corresponding FEs at a series of potentials for TiO 2 /Ti 3 C 2 T x -CP and Ti 3 C 2 T x -CP were measured ( Figure 3B and Figure S11, Supporting Information) and compared ( Figure 3C,D). [61] Furthermore, the TiO 2 / Ti 3 C 2 T x -CP catalyst showed higher NH 3 yield and/ or FE than the behavior of most previous NRR catalysts including VN/TM (8.40 × 10 −11 mol s −1 cm −2 , 2.25%), [62] MoNNA/CC (3.01 × 10 −10 mol s −1 cm −2 , 1.15%), [63] Ag (4.62 × 10 −11 mol s −1 cm −2 , 4.8%), [64] Mo 2 N (78.4 µg h −1 mg −1 cat. at −0.55 V and FE (16.07%) at −0.45 V, which were both higher than those of Ti 3 C 2 T x -CP (NH 3 yield: 22.19 µg h −1 mg −1 cat.…”

Greatly Enhanced Electrocatalytic N2 Reduction on TiO2 via V Doping

“…Figure S5 (Supporting Information) shows the H 2 yield and the corresponding FEs of HER. Combining the data with the obtained NH 3 selectivity, the unaccounted value may be attributed to uncontrollable experimental error and the capacitance of the support as well as dynamic hydrogen adsorption and desorption on the catalyst . The above data clearly show that a highest FE of 15.3% is achieved at −0.40 V and a largest NH 3 yield of 17.73 µg h −1 mg cat.…”

“…The FEs and NH 3 yields gradually increase with negatively applied electrode potential until −0.40 and −0.50 V, respectively. When the potential is below −0.50 V, the FEs and NH 3 yields together decrease, which is attributed to the competition of hydrogen evolution reaction (HER) . Figure S5 (Supporting Information) shows the H 2 yield and the corresponding FEs of HER.…”