The bifunctional 3D-on-2D FeCo/Ni(OH)2 hierarchical nanocatalyst for industrial-level electrocatalytic water splitting

Developing high-performing and cost-effective bifunctional electrocatalysts under the industrial conditions is significant for revolutionizing the hydrogen economy. Herein, we developed a bifunctional 3D-on-2D FeCo/Ni(OH)2 hierarchical nanocatalyst on Ni mesh by a facile and low-cost method that can boost both the two half-reactions of water splitting all at once. The FeCo/Ni(OH)2/Ni mesh showed an outstanding electrocatalytic performance under the industrial conditions (3 M KOH, 90 °C) with applied voltages of 1.47 and 1.91 V to drive the electrolyzer at 10 and 500 mA/cm2, respectively, much better than the Ni(OH)2/Ni mesh, FeCo/Ni mesh, and Raney Ni/Ni mesh samples. Furthermore, it can maintain good stability for more than 192 h under the working condition of 500 mA/cm2. This promotion in electrocatalytic properties can be ascribed to the synergistic effects between 3D FeCo nanoparticles and 2D Ni(OH)2 nanosheets, including the large electrochemically active surface areas, the intense electronic interplay between the two component and the elevated interfacial contact and charge transport. Eventually, this water electrolyzer yields a 14.7% solar-to-hydrogen efficiency when integrated with Si solar cells, which exceeds analogous solar-driven systems reported so far.