Hydrogen-bond induced and hetero coupling dual effects in N-doped carbon coated CrN/Ni nanosheets for efficient alkaline freshwater/seawater hydrogen evolution.

Developing efficient and robust non-precious-metal-based hydrogen evolution reaction (HER) catalysts is highly desirable but remains quite challenging for alkaline freshwater/seawater electrolysis. In the present study, we report a theory-guided design and synthesis of a nickel foam (NF) supported N-doped carbon-coated (NC) nickel (Ni)/chromium nitride (CrN) nanosheets (NC@CrN/Ni) as a highly active and durable electrocatalyst. Our theoretical calculation firstly reveals that CrN/Ni heterostructure can greatly promote the HO dissociation via hydrogen-bond induced effect, and the N site can be optimized by hetero coupling to achieve a facile hydrogen associative desorption, thereby significantly boosting alkaline HER. Guided by theoretical calculation, we prepared the nickel-based metal-organic framework as a precursor, and introduced the Cr by the subsequent hydrothermal treatment, finally obtained the target catalyst by ammonia pyrolysis. Such a simple process ensures the exposure of abundant accessible active sites. Consequently, the as-prepared NC@CrN/Ni catalyst exhibits outstanding performance in both alkaline freshwater and seawater, with the respective overpotential of only 24 and 28 mV at a current density of 10 mA cm, respectively. More impressively, the catalyst also possesses superior durability in the constant-current test of 50 h at the different current densities of 10, 100, and 1000 mA cm.