Recent advances in covalent organic framework (COF) nanotextures with band engineering for stimulating solar hydrogen production: A comprehensive review

Due to the continuous consumption of fossil fuels, natural reserves are depleting and it has been earnest need for developing new sources of energy. Among the several solar energy conversion techniques, photocatalytic hydrogen (H2) generation is regarded as one of the most promising routes. Till date, several metal-based semiconductor materials have been investigated, however, H2 generation is not substantial with the notion of sustainable development. Current research trends show the growing interest in advanced and metal free photocatalyst materials such as covalent organic frameworks (COFs) due to their several benefits such as crystalline porous polymers with pre-designed architectures, large surface area, exceptional stability, and ease of molecular functionalization. By combining COFs with other functional materials, composites may be created that display unique characteristics that exceed those of the separate components. This work provides a comprehensive development on COFs as a photocatalysts and their composites/hybrids for photocatalytic hydrogen generation with a focus on visible-light irradiation. To reduce the dependency on novel metals and overcome the drawbacks of individual material, the creation of composite materials based on covalent-organic frameworks (COFs) are sys-tematically discussed. In addition, advantages in terms of performance, stability, durability of composites/hybrids COFs for photocatalytic hydrogen production in reference to tradi-tional catalysts are investigated. Different composites such as metals loading, morpho-logical development, band engineering, and heterojunctions are systematically discussed. Finally, challenges and opportunities associated with constructing COF-based catalysts as future research prospective for chemistry and materials science are highlighted.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Due to the depletion of fossil fuels, there is an urgent need to develop new sources of energy. Photocatalytic hydrogen (H2) generation, particularly using covalent organic frameworks (COFs), has attracted increasing interest. This research provides a comprehensive overview of COFs as photocatalysts and their composites/hybrids for visible-light-induced hydrogen generation, discussing the development of composite materials and highlighting the challenges and opportunities for constructing COF-based catalysts in chemistry and materials science.