Harnessing the Extracellular Electron Transfer Capability of Geobacter sulfurreducens for Ambient Synthesis of Stable Bifunctional Single‐Atom Electrocatalyst for Water Splitting

Abstract Single‐atom metal (SA‐M) catalysts with high dispersion of active metal sites allow maximum atomic utilization. Conventional synthesis of SA‐M catalysts involves high‐temperature treatments, leading to low yield with a random distribution of atoms. Herein, a nature‐based facile method to synthesize SA‐M catalysts (M = Fe, Ir, Pt, Ru, Cu, or Pd) in a single step at ambient temperature, using the extracellular electron transfer capability of Geobacter sulfurreducens (GS), is presented. Interestingly, the SA‐M is coordinated to three nitrogen atoms adopting an MN 3 on the surface of GS. Dry samples of SA‐Ir@GS without further heat treatment show exceptionally high activity for oxygen evolution reaction when compared to benchmark IrO 2 catalyst and comparable hydrogen evolution reaction activity to commercial 10 wt% Pt/C. The SA‐Ir@GS exhibits the best water‐splitting performance compared to other SA‐M@GS, showing a low applied potential of 1.65 V to achieve 10 mA cm −2 in 1.0 M KOH with cycling over 5 h. The density functional calculations reveal that the large adsorption energy of H 2 O and moderate adsorption energies of reactants and reaction intermediates for SA‐Ir@GS favorably improve its activity. This synthesis method at room temperature provides a versatile platform for the preparation of SA‐M catalysts for various applications by merely altering the metal precursors.