Carbon supported photocatalytic sponges for CO2 reduction and H2 production: Synthesis, properties, future directions

The increasing demand for sustainable and energy-efficient technologies underscores the importance of advancing photocatalysis for environmental and energy applications. This review examines the synthesis, properties, and applications of carbon-supported photocatalytic sponges, which address the challenges of catalyst recovery, reusability, and scalability in current photocatalytic systems. Photocatalytic sponges, offering substantial surface area and structural versatility, are effective for hydrogen production and COQ reduction. Various fabrication methods such as polymerization, freeze-drying, and sol-gel processes enable the development of sponges with tailored properties suitable for these applications. A significant achievement highlighted is the creation of a reusable Ag/AgCl-coated melamine sponge microreactor that fully degrades pollutants like methylene blue in minutes and demonstrates high reusability. Additionally, the pyridazine-doped carbon nitride sponge exhibits enhanced hydrogen evolution rates, attributable to its porous architecture and nitrogen defects. The sponge-based approaches' advantages in environmental remediation and renewable energy production address the scalability and economic considerations critical for real-world applications. Future research directions emphasize optimizing structural and catalytic characteristics of sponges and exploring advanced multifunctional materials to enhance their stability, efficiency, and environmental impact.