Overall water splitting realized by overall sputtering thin-film technology for a bifunctional MoNiFe electrode: A green technology for green hydrogen

Electrode for water electrolysis needs to be prepared by a non-traditional way to overcome the peel-off problem of electrocatalysts under high current. Herein, we use the sputtering technology to prepare the ternary MoNiFe alloys with various Mo contents as bifunctional electrocatalyst for overall water splitting in alkaline solution. The incorporation of Mo atoms in the NiFe host structure improved the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) performance. The bifunctional MNF-2 electrolyte cell requires a cell potential of 1.55 V at 10 mA/cm2. The scale-up single MNF-2 stack cell of 3 × 3 cm2 needed 1.9 and 2.1 V to reach 100 and 500 mA/cm2, respectively. Stability test at 100 mA/cm2 for 100 h showed no degradation. The sputtering thin-film technology can not only deposit excellent catalyst but also provide the strong catalyst/support adherence for industrial application. The excellent activity of MoNiFe is attributed to its composition design.