The article discusses the emergence of hydrogen as a promising energy carrier and its connection to solar energy for hydrogen production. It highlights copper slag, a by-product of copper smelting and refining processes, as a potential sustainable solution for solar-driven hydrogen generation. By utilizing copper slag as a photocatalyst, the waste can be diverted from landfills, and hydrogen can be produced efficiently. The review explores the chemical, physical, photocatalytic, and electrochemical properties of copper slag, evaluating its suitability for water treatment and as a material for large-scale solar hydrogen production. Moreover, the article emphasizes the importance of decarbonizing global energy systems and reducing greenhouse gas emissions to combat climate change. It underlines the potential of hydrogen gas as a clean fuel with high energy yield, surpassing fossil fuels. The article also sheds light on the economic value of copper slag, its various industrial uses, and the possibility of recovering valuable metals from this waste, contributing to sustainable mining practices. With Chile producing a significant amount of copper slag annually, the article proposes the recycling of metals from this waste as a way to recover strategic resources and promote carbon neutrality in the mining industry.