Efficient catalysis of N doped NiS/NiS2 heterogeneous structure

Boosting the catalytic ability of nickel sulfide is vital to its further application as a class of promising non-noble catalysts for energy/environmental applications. In light of the varied structure phase and heteroatom doping effect of nickel sulfide, herein, we demonstrated the excellent catalysis performance for varied reactions catalyzed by nickel sulfide with N doping and heterostructure construction. Different from the usually used corrosive precursors, amidinothiourea and thioacetamide were used as S and N source for the catalysts fabrication, and N atom was doped into the catalysts simultaneously during the sulfuration process. The spectroscopic probing and microscopic observation clearly showed the heterogeneous structure and interface formation. Benefiting from the large surface area, N-doping induced electronic effect and interfacial coupling and synergistic effect between NiS and NiS2, the as-prepared N doped NiS/NiS2 (N-NiS/NiS2) heterogeneous catalyst can realize multifunctional catalysis for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR) efficiently in terms of the high activity, favorable kinetics, rapid charge transfer and strong durability. Specifically, N-NiS/NiS2 catalyst exhibited low overpotentials of 185 and 270 mV to deliver a current density of 10 mA cm−2 for HER and OER in alkaline media, respectively. Meanwhile, the N-NiS/NiS2 catalyst could reach 100 mA cm−2 at 1.47 V for UOR, about 130 mV less for its OER. When integrated into a two-electrode system for water electrolysis, the electrode delivered a potential of 1.62 V to achieve 10 mA cm−2 for urea electrolysis which was 120 mV lower than that of conventional water electrolysis. The work shows the importance of the heterostructure interface construction and hetero-atom doping effect on catalysis ability promotion.