Investigation of anion doping effect to boost overall water splitting

Abstract Developing effective and earth-abundant non-noble electrocatalysts for water splitting to produce clean and eco-friendly hydrogen is necessary in conversion of renewable energy. Pyrite nickel disulfide (NiS2) and nickel diselenide (NiSe2) as electrocatalysts have been extensively researched, but controllable component and superior structure for them are still a huge challenge. For this work, we report a series of flower-like electrocatalysts with Ni(SxSe1−x)2 nanoparticles encapsulated by porous graphitized carbon nanosheets (PGCNS) through regulating molar ratio of S/Se, and reveal ultra-sensitive S/Se species-induced behaviors and the enhanced inherent electrocatalytic activity. The electrocatalytic activities of these anion-tuned sulfoselenides nanoparticles for both HER and OER can be further enhanced by insertion these nanoparticles into PGCNS. By virtue of the most rational doping and the unique architecture, Ni(S0.61Se0.39)2@PGCNS shows the remarkable HER activity While Ni(S0.24Se0.76)2@PGCNS exhibits the excellent OER activity. When these two electrocatalysts with outstanding performance are assembled in a typical two-electrodes system (Ni(S0.61Se0.39)2@PGCNS || Ni(S0.24Se0.76)2@PGCNS) for overall water splitting in 1 M KOH, a current density of 10 mA cm−2 is generated at a low cell potential of 1.54 V. This work emphasizes the significances of anion doping and unique architecture to enhance the activities for electrocatalytic water splitting in energy conversion.