Highly efficient H2 production from H2S via a robust graphene-encapsulated metal catalyst†
The electrocatalytic decomposition of the abundant and toxic H2S from industrial by-products is a promising energy conversion technology for H2 production and simultaneously removing this environmental pollutant. However, the development of such a technology has been hindered by the lack of low-cost, efficient and robust electrocatalysts. Herein, we reported a remarkable graphene-encapsulated metal catalyst, i.e., nitrogen-doped graphene encapsulating a non-precious CoNi nanoalloy as the anode for highly efficient electrocatalytic H2 production from H2S. This optimized catalyst could drive the anode reaction at an onset potential of 0.25 V, which was 1.24 V lower than that required for the water oxidation reaction, and delivered almost twice current density than that of Pt/C. Meanwhile, it exhibited approximately 98% H2 faradaic efficiency and maintained long-term durability for more than 500 h without any decay. The density functional theory calculations revealed that the CoNi and nitrogen dopants synergistically facilitated the formation of polysulfides on graphene's surfaces. Furthermore, a demo showed 1200 h stability for removing H2S impurities from industrial syngas to produce hydrogen by this graphene-encapsulated metal catalyst, demonstrating its great potential for hydrogen production toward sustainable energy applications.