Elucidating Structural Stability, Bandgap, and Photocatalytic Hydrogen Evolution of (H₂O/DMF)@HKUST‐1 Host‐Guest Systems

Abstract

The H2O@HKUST‐1 and DMF@HKUST‐1 systems were experimental and computationally assessed, employing XRD/TGA/FT‐IR/DFT‐calculations, evidencing that H2O or DMF coordinated to Cu, modulating HKUST‐1 photocatalytic properties. DMF@HKUST‐1 has narrower bandgap promoting higher‐crystallinity and light‐harvesting. H2O@HKUST‐1 showed smaller particle sizing and sharp morphology. Theoretical models, (H2O)1@HKUST‐1 and (DMF)1@HKUST‐1, containing one coordinated molecule, elucidated bandgap modulation associated with infiltration. H2O@HKUST‐1/DMF@HKUST‐1 presented bandgaps [eV] of 3.6/3.4, by Tauc plots, and 3.55/3.26, by theoretical calculations, narrowing bandgap, compared with non‐solvated HKUST‐1(HKUST‐1NS). Both composites raised the valence band (VB) and lowered the conduction band (CB), but DMF@HKUST‐1 most raised VB. Topological analysis revealed that guests i) with higher electronic density, raised VB, and ii) induced π‐backbonding, lowering CB. DMF@HKUST‐1 presented a higher photocatalytic hydrogen evolution (µmol), 26.45, in the first 30 min of the reaction, nevertheless, H2O@HKUST‐1 presented a competitive activity, of 17.32. In large periods, H2O@HKUST‐1/DMF@HKUST‐1 showed practically the same hydrogen evolution, 45.50/49.03.

Metal–Organic Frameworks/Heterojunction Structures for Surface-Enhanced Raman Scattering with Enhanced Sensitivity and Tailorability

“…The HKUST-1-BTC system followed a previously reported semiconductor-to-molecule CT mechanism. That is, charges in the VB of HKUST-1 (−7.28 eV) are injected into the LUMO of BTC. , Figure c–e shows the Mott–Schottky spectra of HKUST-1, Cu­(OH) 2 , and HKUST-1/Cu­(OH) 2 , respectively. As displayed in Figures c–d, HKUST-1 and Cu­(OH) 2 show positive and negative slopes of the E–C 2– plots, respectively, which manifest the characteristics of n- and p-type semiconductors.…”

Elucidating, understanding, and correlating the (photo)electrochemical and physicochemical properties of HKUST-1 through an experimental and computational approach

“…An easy methodology (slow evaporation process) 24 was employed to synthesize the HKUST-1 MOF. 25 In short, 200 mg (1 mmol) of trimesic acid (BTC, Sigma Aldrich, CAS number 554-95-0, purity: 95%) was dissolved in 10 ml of dimethylformamide (DMF anhydrous; Sigma Aldrich, CAS number 68-12-2, purity 99.8%) (solution 1); then, a solution containing 689 mg of copper( ii ) nitrate hemi(pentahydrate) (Cu(NO 3 ) 2 ·2.5H 2 O, Sigma Aldrich, CAS number 19004-19-4, purity 98%) (3 mmol) and 10 ml of DMF was added into the solution 1 (drop by drop). The final solution was heated at 70 °C for 24 h. The resulting blue powder was recovered by simple filtration and dried at 90 °C for 24 h in an electric furnace.…”