Biphasic Synthesis of a Sulfur-Doped Reduced Graphene Oxide-Supported Co–Fe Prussian Blue Analogue: An Efficient and Durable Non-Noble Metal-Based Bifunctional Electrocatalyst for OER–ORR

The development of cost-effective, highly efficient, and enduring oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is crucial for large-scale commercialization of fuel cells, regenerative metal–air batteries, and integrated electrolyzers. Herein, we developed a simplistic biphasic synthetic strategy to obtain a nanocomposite of a cobalt Prussian blue analogue (PBCo) uniformly rooted over sulfur-doped reduced graphene oxide (S-rGO) support, i.e., PBCo/S-rGO. The detailed physicochemical characterization of the so-crafted catalyst referred as PBCo/S-rGO in the MS, suggests that the presented synthetic plan paves the way to a rational design of morphology with uniformly dispersed PBCo nanocubes over the basal support of S-rGO. The catalyst witnesses an overpotential (η10) requirement of 340 mV for OER, surpassing commercial RuO2 in 1 M KOH. With an ORR half-wave potential (E1/2) of 0.78 VRHE and a potential gap of just 0.79 VRHE between the otherwise kinetically sluggish processes of OER and ORR, the PBCo/S-rGO outperforms the so-claimed state-of-art nanomaterials designed for the same purpose. The exhaustive structural characterization and in-depth electrochemical investigations clearly establish PBCo/S-rGO as a promising bifunctional OER–ORR electrocatalyst for portable fuel cells, metal–air, especially rechargeable metal–air, batteries, and OER- and ORR-based electrolyzers.