Nitrogen source-regulated biomass-based COF@CNF aerogel: achieving efficient photothermal–photocatalytic synergy

Abstract

The scarcity of freshwater resources and the increasing demand for high-value chemicals have positioned solar-driven energy conversion technologies that integrate efficient photothermal conversion with photocatalytic reactions as key solutions. In this context, COFs have demonstrated unique advantages in bimodal energy conversion. Based on this, a synergistic strategy of “macro-oriented structure and micro-molecular design” is proposed to construct two porous COF@CNF aerogels (TpTt@CNF and TpHt@CNF) and their corresponding evaporators TpTt@CNF@CNT and TpHt@CNF@CNT, denoted as TCE and HCE. The two COFs (TpTt and TpHt) incorporate triazine and heptazine nitrogen sources, respectively, endowing the materials with tunable water-binding capabilities and electronic structures. Coupled solar thermal-photocatalytic experiments demonstrate that oriented 25%-HCE maintains an evaporation rate of 3.27 kg m⁻² h⁻¹ and a H₂O₂ production rate of 16.82 mmol m⁻² h⁻¹ under one sun irradiation. Additionally, in single-performance tests, the oriented 30%-TpHt@CNF achieved the highest hydrogen peroxide generation rate (19.4 mmol m⁻² h⁻¹), while the oriented 25%-HCE exhibited the highest evaporation rate (3.46 kg m⁻² h⁻¹). In summary, the synergistic interaction between the macro-oriented pore structure and nitrogen source regulation within the COF enables efficient coupling of photothermal evaporation and photocatalytic reactions within the same system.