Overcoming poisoning effects of heavy metal ions against photocatalysis for synergetic photo-hydrogen generation from wastewater

The concept of photocatalytic H₂ generation from wastewater provides potential simultaneous solutions for clean energy generation and wastewater remediation, which, however, suffers from the poisoning effect of wastewater-containing heavy metal ions against photocatalysis. Here, an innovative “trash-to-treasure” strategy is proposed to reuse the toxic heavy metal contaminants for enhanced H₂ generation performance from wastewater via synergetic photocatalysis. Through fabricating a transparent adsorbent polysaccharides hydrogel to incorporate photocatalyst without deteriorating its photocatalytic activities, heavy metal ions could be efficiently collected on the well-designed system to minimize their influence on photocatalytic process. Then an in-situ sulfurization process was subsequently introduced to convert the adsorbed heavy metal ions into corresponding metal sulfide semiconductors with narrowed band-gap, concurrently forming heterojunction with incorporated photocatalysts, which resulted in the significantly elevated photocatalytic activities for H₂ generation. Based on the detailed studies on both the performances and mechanism, this general and facial strategy firstly demonstrate the recycling of harmful heavy metal contaminants to overcome the adverse catalyst poisoning effect, and even to accomplish the elevated H₂ photo-generation from wastewater, which may provide a promising yet practical solution for clean energy generation and wastewater purification.