Photo-thermo catalytic hydrogen production along with pollutant degradation by cost-effective carbon materials

Photo-thermo catalysis represents one of the promising technologies for the use of solar energy to produce hydrogen while recovering chemical energy contained in wastewater. However, inefficient utilization of the whole solar spectrum, high water dissociation activation energy, and costly materials restrict its widespread applications. Herein, we propose to use non-plasmonic, metal-free, cost-effective and full-spectrum-responsive nitrogen-doped carbon materials prepared by using urea as a nitrogen source for photo-thermo catalytic hydrogen production in accompany with aqueous pollutant degradation. It is demonstrated that the used carbon materials can successfully produce hydrogen and decompose pollutants simultaneously via photo-thermo catalytic reactions upon illumination even with actual biogas slurry. Moreover, strong oxidants can be generated via photo-thermo catalysis in the presence of dissolved oxygen, which promotes hydrogen production. Particularly, due to the photothermal conversion, the redox reaction over carbon materials is enhanced and the activation energy is decreased, facilitating hydrogen production. The generated hydrogen radicals promote the regeneration of active sites for thermocatalytic hydrogen production. The synergy of photocatalysis and thermocatalysis leads to the promotion of actual biogas slurry degradation and hydrogen production. This work demonstrates a promising, efficient and cost-effective strategy for simultaneous solar hydrogen production and wastewater treatment.