A review of metal-organic frameworks/graphitic carbon nitride composites for solar-driven green H2 production, CO2 reduction, and water purification

The rapid increase in population growth and economic development led to the increase in utilization of fossil fuels energy per capita. Thus, the consumption of these fossil fuel's energy resources poses serious implications for our environment. Photocatalysis plays an essential role in sustainable energy development and environmental remediation. The graphitic carbon nitride (g-C3N4) has been efficiently employed in photocatalysis due to its abundance, low price, high stability, appropriate band gap, and encouraging environmental impacts. As the photocatalytic efficiency of single component g-C3N4 is still not satisfactory for efficient photocatalysis. Hence, its composites with various functional nanomaterials have been widely prepared and employed for efficient photocatalysis. Among the widely coupled functional nanomaterials, metal-organic frameworks (MOFs) have been widely explored for energy production and controlling environmental pollution due to their large surface area, tunable pore size and window, and tailored functionalities. The significance of MOF/g-C3N4 composites flourished for green hydrogen (H2) production, carbon dioxide (CO2) conversion, and environmental pollution control. In this review, we comprehensively highlighted the recent advancements and challenges of g-C3N4 and MOFs heterojunctions in the field of green H2 production. Besides, we discussed the up-to-date applications of g-C3N4-based composites with MOFs for CO2 conversion to useful fuels. Furthermore, the association between MOFs and g-C3N4 composites and their performance for water purification are also discussed. Finally, we proposed the future potential of MOF/g-C3N4 composites to be used for the generation of green energy in order to solve environmental issues. We suggest that this review can help to design MOF/g-C3N4 composite photocatalysts for prospective applications in energy harvesting and controlling environmental pollution.