Bio-inspired synthesis of reduced graphene oxide wrapped Geobacter sulfurreducens as a hybrid electrocatalyst for efficient oxygen evolution reaction

Abstract

Doping/decorating of graphene or reduced graphene oxide (rGO) with heteroatoms provides a promising route for the development of electrocatalysts useful in many technologies, including water splitting. However, current doping approaches are complicated, not eco-friendly and not cost-effective. Herein, we report the synthesis of doped/decorated rGO for oxygen evolution reaction (OER) using a simple approach that is cost-effective, sustainable and easy to scale up. The OER catalyst was derived from the reduction of GO by an exo-electron transferring bacterium, Geobacter sulfurreducens. Various analytical tools indicate that OER active elements such as Fe, Cu, N, P, and S decorate the rGO flakes. The hybrid catalyst (i.e., Geobacter/rGO) produces a geometric current density of 10 mA cm−2 at an overpotential of 270 mV vs. the reversible hydrogen electrode (RHE) with a Tafel slope of 43 mV dec−1, and possesses high durability, evidenced through 10 hours of stability testing. Electrochemical analyses suggest the importance of Fe and its possible role as active site for OER. Overall, this work represents a simple approach towards the development of earth-abundant, eco-friendly and highly active OER electrocatalyst for various applications such as solar fuel production, rechargeable metal-air batteries, and microbial electrosynthesis.