Hydrogel-Based Photocatalysts: Applications in Environmental Remediation and Energy Conversion

Photocatalysis, a green energy technology that effectively addresses environmental pollution and energy scarcity, has garnered significant attention. However, the widespread use of powdered photocatalysts poses low utilization of irradiation light and separation efficiency, and recycling challenges. To address these challenges, hydrogel photocatalysts with enhanced activity and stability have been developed by incorporating active substances into hydrogels for environmental remediation and energy conversion. In this review, we summarize various studies conducted in recent years, focusing primarily on diverse hydrogel-based photocatalysts that exhibit significant potential for the removal of pollutants from wastewater and in energy conversion applications. The review offers a classification of hydrogel-based photocatalysts, encompassing graphene hydrogel-based, natural polymer hydrogel-based, and free-radical polymerization hydrogel-based photocatalysts. Furthermore, it systematically summarizes the recent advancements in the application of hydrogel-based photocatalysts for environmental remediation, including the treatment of dyes, antibiotics, heavy metal ions, and pesticides, as well as for energy conversion processes such as hydrogen production, H2O2 generation and CO2 conversion. Finally, this review offers insights and recommendations for the further development of hydrogel-based photocatalysts, aiming to foster the progress of photochemical catalysis in the future.