Encapsulated Rh nanoparticles in N-doped porous carbon polyhedrons derived from ZIF-8 for efficient HER and ORR electrocatalysis

Abstract

Searching for efficient and durable electrocatalysts toward hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) is highly desirable for the development of sustainable energy conversion technologies, but still remains a great challenge. Here, high-dispersed Rh nanoparticles are successfully encapsulated in the pores of N-doped porous carbon polyhedrons (NPCP) derived from ZIF-8 to avoid their aggregation and detachment, which makes the electrocatalyst (Rh@NPCP) have high activity and good stability. With an accepted metal loading (9.84 wt% Rh), Rh@NPCP exhibits excellent activity for HER electrocatalysis with ultralow overpotentials of 20, 23 and 45 mV to reach a current density of 10 mA cm−2 in alkaline, acidic and neutral media. Besides, remarkable ORR electrocatalytic activity with a half-wave potential of 0.84 V in alkaline media is achieved. Compared to the commercial Pt/C catalyst (20 wt% Pt), the prepared Rh@NPCP catalyst demonstrates significantly superior electrocatalytic performance toward pH-universal HER and alkaline ORR, especially in stability. This work provides a highly efficient, durable and affordable electrocatalyst for HER and ORR, which may have practical applications in water splitting and fuel cells.