Synergistic coupling of NiFe-layered double hydroxide nanosheets with Co-doped porous interconnecting carbon frameworks for efficient bifunctional electrocatalysis

The design of low-cost and durable electrocatalysts with high catalytic performance of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for the development of sustainable energy technologies. NiFe-layered double hydroxide (NiFe-LDH) is a promising electrocatalyst for OER, but the poor ORR activity limits its large-scale application as a bifunctional electrocatalyst in energy storage and conversion devices. The rational design of hierarchical nanohybrids is an effective strategy to construct bifunctional OER/ORR electrocatalysts. Herein, a high-performance OER/ORR bifunctional non-noble metal electrocatalyst (NiFe-LDH/CoNC-PIN) was projected. The Co-doped carbon frameworks with porous interconnecting networks (CoNC-PIN) is prepared by pyrolysis of ZIF-8/67 via a salt template strategy, followed by the uniform in situ growth of ultrathin NiFe-LDH nanosheets on CoNC-PIN to construct the hierarchical NiFe-LDH/CoNC-PIN hybrid. The molten NaCl template in pyrolysis activates the surface of ZIF-8/67 and connects them into porous carbon networks to improve the surface area, porosity and electronic conductivity of catalysts. Due to the efficient electron transfer and strong coupling between CoNC-PIN and NiFe-LDH, the NiFe-LDH/CoNC-PIN exhibits a small OER overpotential of 249 mV at 10 mA/cm2, a low Tafel slope of 27.7 mV/dec, an ORR half-wave potential of 0.80 V, and excellent durability and structural stability. This strategy provides a novel insight to fabricate advanced OER/ORR bifunctional non-noble metal electrocatalysts.