Highly Crystalline Mesoporous Silicon Spheres for Efficient Visible Photocatalytic Hydrogen Evolution

Abstract High‐performance and low‐cost photocatalysts from earth‐abundant sources are of great importance to realize large‐scale hydrogen production. Silicon, a naturally abundant semiconductor with narrow bandgap, is an ideal photocatalyst due to its high solar energy utilization efficiency; however, its application in photocatalytic H₂ production is mainly limited by energy band and surface structures. Here we report the facile synthesis of highly crystalline mesoporous silicon spheres to overcome the limitations by combining salt‐assisted aerosol synthesis with magnesiothermic reduction. The mesoporous silicon spheres possess high crystallinity, large specific surface area and optimal band structure, enabling efficient and stable photocatalytic H₂ evolution (1785 μmol h⁻¹ g⁻¹) under visible light without precious metal cocatalysts. This work offers a scalable approach to highly crystalline mesoporous materials and provides new prospects in developing silicon photocatalysts for solar fuel production.