Comparative Study\non Photocatalytic Hydrogen Production\nEfficiency of Benzodifuran-Based Covalent Organic Frameworks: Impact\nof Carboxamide and Ethyl Carboxylate Side Chains

Visible light-driven hydrogen production from water using\nsolar\nenergy for chemical conversion represents a promising technological\nadvancement. Among the competitive photocatalysts, covalent organic\nframeworks have garnered considerable attention. In this study, we\nintroduce carboxamide side chains into benzodifuran-based covalent\norganic frameworks (<b>BDF-COF-1</b>) to propose an efficient\nstrategy for photocatalytic hydrogen production. Additionally, a benzodifuran\ncovalent organic framework featuring ethyl carboxylate side chains\n(<b>BDF-COF-2</b>) was synthesized to contrast with <b>BDF-COF-1</b>. Notably, <b>BDF-COF-1</b> exhibited exceptional photocatalytic\nactivity under visible light irradiation, achieving a hydrogen production\nrate of 57.48 mmol g<sup>–1</sup> h<sup>–1</sup>, significantly\nsurpassing that of <b>BDF-COF-2</b> under identical conditions\n(4.40 mmol g<sup>–1</sup> h<sup>–1</sup>).