Highly efficient electrochemical hydrogenation and dehydrogenation of quinoline catalyzed by a bifunctional RuNi electrode

Abstract

Liquid organic hydrogen carriers (LOHCs) are considered highly promising materials for hydrogen storage due to their potential to store hydrogen under mild conditions. However, traditional hydrogenation and dehydrogenation methods for LOHCs often require harsh conditions and rely on exogenous hydrogen donors, limiting their practical application. Therefore, developing an efficient method to catalyze LOHCs hydrogenation and dehydrogenation at room temperature using a safe and clean hydrogen source is of significant scientific and practical importance. This paper presents an efficient and reversible electrochemical hydrogen storage system based on the nitrogen heterocyclic organic hydrogen carrier, quinoline. Here, the RuNi/NF electrode serves as an electrocatalyst to produce 1,2,3,4-tetrahydroquinoline (THQ) under ambient conditions, utilizing H₂O as a hydrogen source with up to 99% conversion and 99% selectivity. Quinoline was synthesized with 94% conversion and 92% selectivity within the same solution system. This exceptional performance is attributed to the RuNi alloying effect, which enhances both the affinity of the active hydrogen atom (H∗) in the solution and the activity of Ni²⁺ in the catalyst. Furthermore, the RuNi electrocatalyst exhibits excellent catalytic stability. The use of water as a hydrogen source eliminates the need for exogenous hydrogen, ensuring the safety of the process. This study provides an environmentally friendly and safe strategy for hydrogen storage in nitrogen heterocyclic organic carriers. By achieving efficient hydrogenation and dehydrogenation of LOHCs through electrochemical methods, this work not only expands the technical pathways for hydrogen storage but also offers important theoretical and practical insights for the development of future clean energy technologies.