Figure 9.

Selected synthetic electrocatalysts that mimic the [Mn₄Ca]-cluster and the active sites of hydrogenases. Synthetic [Mn₃CaO₄]-clusters designed by Agapie and co-workers (a) [87] and Christou and co-workers (b) [88]; Co₄O₁₆ core stabilized within [PW₉O₃₄] ligand synthesized by Hill and co-workers (c) [89]; Nocera CoPi solid catalyst and its proposed atomic structure (d) [90]; synthetic [FeFe] and [NiFe] models designed by Pickett and co-workers [91] and Ogo and co-workers [92] (e) and (f); bioinspired model designed by Dubois and co-workers (g) [93].