Chem Catalysis
Volume 2, Issue 7, 21 July 2022, Pages 1764-1774
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Article
Ruthenium/titanium oxide interface promoted electrochemical nitrogen reduction reaction

https://doi.org/10.1016/j.checat.2022.05.009Get rights and content
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Highlights

  • Greatly improved ammonia Faradaic efficiency with suppressed HER

  • Interface engineering to control the binding strength of reactive intermediates

  • In situ spectroscopies to observe N–H-related intermediates during eNRR

The bigger picture

As a key process of ammonia-based energy prospective, ammonia synthesis via the electrochemical nitrogen reduction reaction (eNRR) at ambient conditions has been widely studied in recent years. However, the poor selectivity and low yield of ammonia are still the main challenges due to the slow kinetics of the eNRR and the competing hydrogen evolution reaction (HER). Herein, we present a simple method to prepare Ru/TiO2 that exhibits high Faradaic efficiency for the eNRR toward producing ammonia. By a sophisticated design of the Ru/TiO2 interface, the binding strength of H-related intermediates is weakened, while the binding strength of N2-related intermediates is strengthened, resulting in promoted reaction kinetics of the eNRR with suppressed HER. This work provides an effective and controllable method of interfacial engineering to boost the activity and selectivity of the electrochemical reaction by controlling the binding strength of reactive intermediates.

Summary

The electrochemical nitrogen reduction reaction (eNRR) offers a promising strategy to synthesize ammonia at ambient conditions. However, the selectivity and yield of ammonia are greatly impeded by the slow kinetics of the eNRR and the competing hydrogen evolution reaction (HER). Herein, we find that by growing Ru nanoparticles on rutile TiO2, the intimate electronic coupling between Ru nanoparticles and TiO2 support is able to greatly promote the first protonation of N2 via an associative mechanism in the eNRR while suppressing the HER, resulting in a greatly improved ammonia Faradaic efficiency of 40.7% and yield of 10.4 μgNH3 h−1 cm−2geometric area at −0.15 V versus the reversible hydrogen electrode (RHE) in 0.5 M K2SO4 aqueous solution at room temperature and ambient pressure. Our work provides a general approach to achieve selective electrochemical reaction by controlling the binding strength of reactive intermediates via interface engineering.

Keywords

electrochemical nitrogen reduction reaction
ruthenium
titanium oxide
interface
in situ

UN sustainable development goals

SDG7: Affordable and clean energy

Data and code availability

This study did not generate any datasets.

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6

These authors contributed equally

7

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