Hierarchical macro-mesoporous g-C3N4 with an inverse opal structure and vacancies for high-efficiency solar energy conversion and environmental remediation

Hierarchical macro-mesoporous structures with an efficient mass transfer and light harvesting offer great advantages for photocatalysis. Nitrogen vacancy modified ordered hierarchical macro-mesoporous g-C₃N₄ (Nv MM CN) was fabricated by a dual-templating method combining an ordered SiO₂ colloidal crystal and NH₄Cl. The as-prepared Nv MM CN was applied for photocatalytic degradation of antibiotics and production of hydrogen. Nv MM CN showed 27 times higher photocatalytic degradation efficiency and 7.5 times higher hydrogen production than bulk g-C₃N₄ (Bulk CN) under visible light irradiation. The 3D well interconnected macro-mesoporous structure and the porous system accelerated adsorption as well as the reaction rate and the inverse opal photonic crystals provided multiple scattering effects to strengthen light absorption. Meanwhile, the nitrogen vacancy introduced acted as a separation center to capture electrons or holes to improve the separation efficiency of charges. This efficient, stable, and environmentally friendly visible light-driven Nv MM CN may be an alternative for effective implementation in wide-ranging energy and environmental applications.