A Full-Spectrum-Responsive MOF-on-MOF Heterojunction Photocatalyst for Concurrent Nitrate Reduction and Biomass Oxidation.

Photocatalytic nitrate reduction reaction (PNitRR) offers a sustainable route for ammonia (NH3) synthesis and wastewater treatment. The insufficient utilization of near-infrared (NIR) light and sluggish reaction kinetics of coupled water oxidation result in unsatisfactory performance. Herein, a conductive metal organic framework (cMOF)-on-cMOF S-scheme heterojunction is reported as an efficient full-spectrum photocatalyst for driving an innovative hybrid system of PNitRR to NH3 and photocatalytic 5-hydroxymethylfurfural oxidation reaction (PHMFOR) to 2, 5-furandicarboxylic acid (FDCA). The integration of Co-cMOF and Ni-cMOF with dual NIR-response features and well-matched band structures into an S-scheme heterojunction enables sufficient light utilization and efficient charge separation. Moreover, the formation of interfacial Ni-Co dual sites with modulated electronic structures accounts for PNitRR and PHMFOR, respectively, with enhanced activity and selectivity. The designed cMOF-on-cMOF S-scheme heterojunction photocatalyst exhibits production rates of 4677.5 and 5932.5 µmol gcat -1 h-1 with apparent quantum yields of 13.3% and 13.1% at 500 nm for NH3 and FDCA production, respectively. This work opens new avenues for the development of advanced photocatalysts and integrated photocatalytic systems to produce valuable chemicals.