Polyarylimide-Based COF/MOF Nanoparticle Hybrids for CO2 Conversion, Hydrogen Generation, and Organic Pollutant Degradation

The continuous rise in atmospheric CO2 concentration, overconsumption of energy resources, and release of extraordinary organic pollutants are challenging issues of the modern era. Catalytic technology offers a promising solution to tackle these energy and environmental challenges in parallel by facilitating highly effective and sustainable processes. Herein, we report the fabrication of a series of different nature polyarylimide (PAI)-based covalent-organic frameworks (COFs) via the polycondensation reaction by altering linkers, organic solvents, and other experimental conditions. To optimize their catalytic performance, the resultant PAI-COFs were further decorated with metal-organic frameworks (ZIF-67). The decoration of COF4 with ZIF-67 led to adjusted bandgaps, created an active site, enhanced charge separation and migration of photoexcited electron-hole (e-h) pairs, extended the light absorption to the visible region, and also facilitated the transferring of electrons between the COFs and MOFs via the photoelectron modulation approach. Based on our findings, it is confirmed that COF4 and ZIF-67 (MOFs) are the optimal catalysts compared to the other COFs (COF1, COF2, and COF3) and MOFs (ZIF-8). Interestingly, compared to the pristine COF4, the 5ZIF-67/COF4 nanohybrid revealed similar to 8-fold and similar to 5.3-fold for CO2 conversion, direct CO2 capturing, and photoelectrochemical CO2 conversion with a faradaic efficiency of 50%. Likewise, the as-fabricated catalyst also exhibits exceptional activities for photocatalytic hydrogen production and pollutant oxidation. Ultimately, this work will provide a roadmap for the design and fabrication of COF-based nanohybrids for energy and environmental applications.