Multi‐Site Electrocatalysts Boost pH‐Universal Nitrogen Reduction by High‐Entropy Alloys

Abstract

Electrocatalytic nitrogen reduction reaction (NRR) has been an important area for many scientists. However, high voltage requirements, low NH3 yield, and poor stability remain the biggest challenges for NRR. Here, novel high‐entropy alloys RuFeCoNiCu nanoparticles with small size (≈16 nm) and uniformity, prepared in oil phase at atmospheric pressure and low temperature (≤250 °C) are reported for the first time and are applied to NRR. According to the experiments, there is a high NH3 yield at a low overpotential. It has a surprising NH3 yield of 57.1 µg h–1 mgcat−1 (11.4 µg h–1 cm–2) at 0.05 V versus RHE in 0.1 m KOH, and the corresponding Faradaic efficiency reaches 38.5%, which is the electrocatalyst with the highest NH3 yield at the voltage of 0.05 V versus RHE reported so far. Similarly, the material also exhibits excellent electrochemical properties in other electrolytes such as 0.1 m Li2SO4, 0.1 m Na2SO4, and 0.1 m HCl electrolytes. Besides, after the 100 h test, only slightly diminished in activity. Theoretical calculation shows that Fe surrounded by alloy metals is the best site for N2 adsorption and activation. Co‐Cu and Ni‐Ru couples show an excellent capacity to surface hydrogenation at a low overpotential.

Generation of high-density nanoparticles in the carbothermal shock method

“…The Cu NPs on cellulose/carbon paper (Cu/cellulose/CP) showed a high ethylene selectivity of 48.92% at a potential of −0.529 V versus the reverse hydrogen electrode (RHE) and stability over 30 hours of reaction in a 10 M KOH electrolyte. This study demonstrated how cellulose enables high surface coverage of metal NPs, which opens the possibility of applying metal NPs and multicomponent NPs to more diverse applications ( 7 , 16 – 19 ).…”

High‐entropy alloys and compounds for electrocatalytic energy conversion applications

“…The compositional and structural diversities of HEAs and HECs give us a new avenue of regulating their surface electronic structures and catalytic performances. Hence, the use of HEA and HEC NPs for electrocatalysis is highly attractive owing to their impressive catalytic activity, excellent selectivity, and good durability 3,46,48,80,81,92–97 . To highlight the potentials of HEAs and HECs, we focus on the discussion of some recent examples of important electrocatalytic reactions, including HER, OER, oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO 2 RR), nitrogen reduction reaction (NRR), MOR, and ethanol oxidation reaction (EOR).…”

“…However, the synthesis of highly efficient and robust electrocatalysts still remains to be a challenge for NRR. For the first time, Wang and coworkers designed a novel quinary HEA (RuFeCoNiCu) NPs with a small size (∼16 nm) and uniformity using the oil phase method at atmospheric pressure and low temperature (≤250 °C) 94 . The synthesized HEA NPs was then applied to the electrochemical NRR and showed extraordinary catalytic activity and stability, with a NH 3 yield rate of 11.4 μg h −1 cm −2 and a Faradaic efficiency of 38.5% at 0.05 V versus RHE in 0.1 M KOH electrolyte (Figures 9G–I).…”

Nanomaterials for the electrochemical nitrogen reduction reaction under ambient conditions

“…When multiple H atoms are adsorbed, they are mainly distributed over the hollow positions, and the adsorption energy decreases rapidly with the H coverage. 148 Fig. 7 (a) Schematic depicting functions of Pt/Au@ZIF.…”

“…Copyright 2020, Wiley-VCH. 148 Therefore, the surface H adsorption will affect the Co-Ni-Ni sites, but the optimal site of NRR, t-Fe, is not at a hollow position and will not be affected significantly. Clearly, different metals may play different roles and work in a synergetic way to provide outstanding NRR performance (Fig.…”