Transforming Ni‐Coagulated Polyferriertic Sulfate Sludge into Porous Heteroatom‐Doped Carbon‐Supported Transition Metal Phosphide: An Efficient Catalyst for Oxygen Evolution Reaction

The transformation of sludge waste from wastewater treatment plants into functional materials is an attractive prospect. Herein, the successful synthesis of mesoporous heteroatom‐doped carbon‐supported NiFe phosphide (FeNi 2 P@HDC) from Ni‐coagulated iron sludge by forming a biogenic precursor via incubation of the sludge with Shewanella oneidensis MR‐1, followed by a simple pyrolysis process, is reported. The incubation results in the formation of a solid chemical bonding between bacteria and the surface of the newly formed mineral, which is beneficial for producing a desirable microstructure and chemical composition. The as‐synthesized FeNi 2 P@HDC shows a superior oxygen evolution reaction (OER) performance, evident from the data, including a low overpotential of 280 mV to reach a current density of 10 mA cm −2 and a small Tafel slope of 56 mV dec −1 under alkaline conditions, which is comparable with that of the majority of the reported Ni and/or Fe phosphide catalysts in the literature and better than the state‐of‐the‐art RuO 2 catalyst. Such a good performance seems to be the result of the synergistic effect of the intrinsic activity of FeNi 2 P nanoparticles and the strong interaction between FeNi 2 P and heteroatom‐doped graphene‐like carbon support.