Biology‐Based Synthesis of Nickel Single Atoms on the Surface of Geobacter sulfurreducens as an Efficient Electrocatalyst for Alkaline Water Electrolysis

Abstract Single‐atom metal catalysts are promising electrocatalysts for water electrolysis. Nickel‐based electrocatalysts have shown attractive application prospects for water electrolysis. However, synthesizing stable Ni single atoms using chemical and physical approaches remains a practical challenge. Here, a facile and precise method for synthesizing stable nickel single atoms on the surface of Geobacter sulfurreducens using a microbial‐mediated extracellular electron transfer (EET) process is demonstrated. It is shown that G. sulfurreducens can effectively anchor nickel single atoms on their surface. X‐ray absorption near‐edge structure and Fourier‐transformed extended X‐ray absorption fine structure spectroscopy confirm that the nickel single atom is coordinated to nitrogen in the cytochromes. The as‐synthesized nickel single atoms on G. sulfurreducens exhibit excellent bifunctional catalytic properties for alkaline water electrolysis with low overpotential ( η ) to achieve current density (10 mA cm ⁻² ) for both hydrogen evolution reactions ( η = 80 mV) and oxygen evolution reaction ( η = 330 mV) with minimal catalyst loading of 0.0015 mg Ni cm ⁻² . The nickel single‐atom catalyst shows long‐term stability at a constant electrode potential. This synthesis method based on the EET capability of electroactive bacteria provides a simple and scalable approach for producing low‐cost and highly efficient nonnoble transition metal single‐atom catalysts for practical applications.