Photocatalysis offers a credible and prompt approach to solving the growing problems of environmental pollution and energy shortages. However, the practical application of photocatalytic materials still faces the challenge of the efficient catalytic system without secondary recovery. Herein, hollow Fe2O3 mi-crospheres with uniform size (polydispersity index = 0.067) were synthesized using an innovative microgel template-assisted solvothermal method with high yield. Via direct writing three-dimensional printing, the as-prepared Fe2O3 microspheres and graphene oxide were fabricated into an ultralight, stable, and high-performance aerogel microreactor, achieving wastewater treatment without catalyst recovery. Photocatalytic degradation efficiency of rhodamine B achieved 97.8% by the microreactor under simulated sunlight irradiation for 120 min. The rich porous structures and highly interconnected net-works of the microreactor provide high specific surface area and increased numbers of multidimensional mass transfer channels, further enabling the catalytic performance and reusability for photocatalytic degradation. (C) 2021 Elsevier Ltd. All rights reserved.