Three-dimensional interconnected nanofibers consisting of ultra-small Ni-doped Co3O4 nanoparticles for acidic overall water splitting at high current density

Exploring earth-abundant electrocatalysts to replace platinum/iridium for acidic overall water splitting at high current density is an important challenge towards lowering the cost of green hydrogen production. Herein, we developed a new class of three-dimensional interconnected nanofibers (NFs) composed of ultra-small Ni-doped Co3O4 nanoparticles (Ni-Co3O4 NFs). Benefiting from the unique ultra-small Ni-doped Co3O4 composition and three-dimensional interconnected porous structure, 13.4 % Ni-Co3O4 NFs (Ni doping is 13.4 wt%) exhibits remarkable electrocatalytic performance in acidic media. Specially, in strongly acidic environments, high activity and high stability overall water splitting can be achieved at high current density. As evidenced by the fact that a voltage of 500 mA cm−2 can be achieved at only 1.86 V and operational stability can be maintained at 500 mA cm−2 for 100 h. [Display omitted] •We develop a new class of 3D interconnected nanofibers composed of ultra-small Ni-doped Co3O4 nanoparticles.•Benefiting from the unique structural, 13.4 % Ni-Co3O4 NFs exhibits remarkable HER and OER performance in acidic media.•13.4 % Ni-Co3O4 NFs exhibits highly active and stable overall water splitting at acidic high current density.•DFT calculations show that the doping of Ni optimizes the electronic structure of Co and prevents the dissolution of Co.