Facile Synthesis of Magnetite‐Rich Core‐Shell Catalysts with Tunable Nanostructure and Atomic Composition from Solid Waste for Superior Water–Gas Shift Reaction

Nanostructured catalysts show superior performance in terms of reaction selectivity and efficiency compared to the bulk catalysts. However, the former are normally synthesized by high‐purity chemicals of high cost, which compromises their advantages from the whole process analysis. In contrast, solid waste containing the desirable metal elements is a promising precursor to synthesize the corresponding nanostructured catalysts with comparable or even improved catalytic performance with the increased catalytic sites available via the deliberate atom doping from the co‐existing impurity cations. Herein, the core‐shell nanostructured magnetite particles are successfully prepared from red mud, a massive solid waste generated from the alumina industry, and the shell thickness, elemental composition, and porosity can be controlled simultaneously by adjusting the pH values of the precipitation. At the optimized pH value of 6, the obtained core‐shell nanostructured particles exhibit outstanding catalysts for high‐temperature water‐gas shift reaction with high reaction efficiency comparable to the literature. The work demonstrates that refining valuable metal sources from wastes is a cost‐effective alternative to prepare nanostructured catalysts of high value, which can benefit upcycling of solid waste for sustainable industry and environmental protection.