Efficient Water Splitting Using a Simple Ni/N/C Paper Electrocatalyst

An efficient water splitting electrocatalyst is presented. Cheap and sustainable cellulose filter paper, infiltrated with nickel acetate as the nickel source, and phenanthroline as a ligand and nitrogen source are carbonized together. Nitrogen functionalities turn out to be crucial coordination sites for the supported Ni/NiO(OH) particles. This simple and scalable one step procedure leads to powders, but also to complete membranes made of ≈10 wt% Ni, supported on nitrogen functionalized carbon. The non‐noble catalyst shows a low onset potential (330 mV vs reversible hydrogen electrode), high current density (e.g., j > 25 mA cm^?­2 at η = 430 mV), excellent kinetics (Tafel slope of 44 mV dec^?1), and a very favorable stability (<5% decay after 10 h electrolysis) in the oxygen evolution. The performance is similar or even better compared to state‐of‐the‐art noble metal catalysts (e.g., IrO₂, Ir/C, Ru/C, and Pt/C). Because of the simple, cheap, and scalable preparation procedure the catalyst is highly promising for practical low price/tech applications. Interestingly, the system is also active in the hydrogen evolution reaction, leading to a promising bifunctional catalyst. The benchmark characteristics are η₁₀ = 390 mV for oxygen evolution and η₁₀ = 190 mV for hydrogen evolution, that is, an overall efficiency of 68% at 10 mA current density.