Reversible hydrogen storage Liquid organic hydrogen carriers (LOHCs) is one of the key technologies for efficient utilization of hydrogen energy. How to construct efficient dehydrogenation/hydrogenation catalysts that enable low-temperature catalysis still remains challenging. Herein, we present the design and construction of single-atom Co-N-C(x) catalysts allowing significantly improved acceptorless dehydrogenation of 1,2,3,4-tetrahydroquinoline (THQ). By varying the ligand/Co ratio, the optimal Co-N-C(1.5) can achieve 97.5% dehydrogenated product and 0.82 h TOF value at ambient temperature, overperforming many reported non-noble metal even noble metal catalysts. This catalyst exhibits good recyclability and substrate versatility, enabling ambient temperature dehydrogenation of various N-heterocycles and efficient reverse hydrogenation of aromatic N-heterocycles, thus achieving the loop of reversible hydrogen storage. The active catalyst centers consist of specific Co-N moieties and nitrogen species within the carbon support. Controlled experiments reveal that the different performance of Co-N-C(x) is determined by density of the Co-N, and the rate-determining step of THQ dehydrogenation is correlated with the bond cleavages in surface-bound THQ. This work offers a promising pathway for energy-efficient and cost-effective hydrogen energy utilization under practical conditions.

中文翻译：

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单原子Co-NC催化剂上N杂环的无受体环境温度脱氢和可逆加氢

可逆储氢液态有机氢载体（LOHCs）是氢能高效利用的关键技术之一。如何构建能够实现低温催化的高效脱氢/加氢催化剂仍然具有挑战性。在此，我们介绍了单原子 Co-NC(x) 催化剂的设计和构造，可显着改善 1,2,3,4-四氢喹啉 (THQ) 的无受体脱氢反应。通过改变配体/Co的比例，最佳的Co-NC(1.5)在环境温度下可以实现97.5%的脱氢产物和0.82 h TOF值，优于许多报道的非贵金属甚至贵金属催化剂。该催化剂表现出良好的可循环性和底物通用性，能够实现各种N-杂环的常温脱氢和芳香族N-杂环的高效反向加氢，从而实现可逆储氢的循环。活性催化剂中心由碳载体内的特定Co-N部分和氮物质组成。对照实验表明，Co-NC(x) 的不同性能是由 Co-N 的密度决定的，THQ 脱氢的速率决定步骤与表面结合的 THQ 中的键断裂相关。这项工作为实际条件下高效、经济的氢能利用提供了一条有前途的途径。