Engineering bidirectional CMC-foam-supported HKUST-1@graphdiyne with enhanced heat/mass transfer for the highly efficient adsorption and regeneration of acetaldehyde

Abstract

Carboxymethyl cellulose-foam-supported HKUST-1@graphdiyne (HK@GDY/CMC-B) was constructed with high thermal conductivity and directional channels to enhance the ad-/de-sorption efficiency of acetaldehyde. Characterization results showed that (1) HKUST-1 grew within CMC and GDY via an in situ tri-phase cross-linking strategy, forming a special “alkynyl|Cu|COOH” interface, which maintained the high BET surface area (945.1 m² g⁻¹) of the HK@GDY/CMC-B foam and established a tight connection among the different components of the composite; (2) the π-conjugated carbon structure of GDY and the unique “alkynyl|Cu|COOH” interface within HK@GDY/CMC-B accelerated the phonon conduction and significantly enhanced the thermal conductivity of HK@GDY/CMC-B (336 mW m⁻¹ K⁻¹); (3) the directional channels and the hierarchical pore structure with a unique interface in the HK@GDY/CMC-B foam facilitated the diffusion and adsorption of VOCs; (4) the compact “alkynyl|Cu|COOH” interface generated more unsaturated Cu(II) and Cu(I) sites and increased adsorbent surface polarity to capture acetaldehyde. Consequently, the obtained HK@GDY/CMC-B exhibited an excellent acetaldehyde adsorption capacity of up to 11.0 mmol g⁻¹, which was 1.3–3.4 times higher than that of many state-of-the-art adsorbents. Kinetics performance data revealed that the diffusivity of acetaldehyde on the HK@GDY/CMC-B foam increased by 60% compared to that of the pristine HKUST-1. Similarly, the desorption rate of HK@GDY/CMC-B was 2.2–6.5 times faster than that of several state-of-the-art adsorbents under similar temperature programmed desorption. This greatly realized an energy-conserving approach for adsorbent regeneration. Based on these findings, the current tri-phase cross-linking strategy can be deemed as an efficient tactic to further improve the adsorption efficiency of MOFs for fast adsorption of VOCs on the commercial level.