Novel V-doped CuCoN0.6/Ni4N heterojunction for boosting water electrolysis by facilitating water dissociation and H* adsorption-desorption kinetics

The high water dissociation energy and the slow H* adsorption-desorption kinetics are the main factors limiting hydrogen evolution reaction (HER) in neutral and alkaline solutions. Herein, V-CuCoN0.6/Ni4N is designed and fabricated by combining the advantages of V-doping and heterojunction to overcome the above two problems. Theoretical calculations proved that the simultaneous existence of heterojunction and V-doping in CuCoN0.6/Ni4N can adjust the electronic structure of the catalyst to reduce water dissociation energy for obtaining abundant H* and optimize H* Gibbs free energy close to zero for enhancing the H* adsorption-desorption process. It is found that V-CuCoN0.6/Ni4N shows low HER overpotentials (Alkaline: eta(-10/-100) = 34/129 mV; N eutral: eta(-10/-100) = 85/230 mV) and Tafel slopes (Alkaline: 73 mV dec(-1); Neutral: 89 mV dec(-1)). The catalyst synthesized in this work not only offers high HER performances, but also provides an ideal way to design and prepare catalysts for hydrogen production by water electrolysis in neutral and alkaline media.