Abstract: Sn₃O₄, a common two-dimensional semiconductor photocatalyst, can absorb visible light. However, owing to its rapid recombination of photogenerated electron−hole pairs, its absorption is not sufficient for practical application. In this work, a Sn nanoparticle/Sn₃O_4−x nanosheet heterostructure was prepared by in situ reduction of Sn₃O₄ under a H₂ atmosphere. The Schottky junctions formed between Sn and Sn₃O_4−x can enhance the photogenerated carrier separation ability. During the hydrogenation process, a portion of the oxygen in the semiconductor can be extracted by hydrogen to form water, resulting in an increase in oxygen vacancies in the semiconductor. The heterostructure showed the ability to remove Rhodamine B. Cell cytocompatibility experiments proved that Sn/Sn₃O_4−x can significantly enhance cell compatibility and reduce harm to organisms. This work provides a new method for the fabrication of a Schottky junction composite photocatalyst rich in oxygen vacancies with enhanced photocatalytic performance.