 Metal-calcogenide nanomaterials have shown great promise in catalyzing the water-splitting reaction, which can be used to generate clean energy from renewable sources. These materials can be synthesized using a variety of techniques, and their morphologies and structures can be manipulated to optimize their catalytic activity. Despite these advances, there remain several challenges that need to be addressed before this technology can be fully realized. This article was authored by Jiayin, Jingjing, Honghong Lin, and others.