No abstract

Tuning the structural defects of graphite carbon nitride (g-C3N4) is an effective strategy to modify its band structure and promote charge separation, but it is still limited by complex and harsh preparation processes. Herein, g-C3N4 with nitrogen defects were fabricated by one-pot thermal polymerization of urea and fumaric acid. The N–(C)3 site, being the active site for photocatalytic hydrogen evolution, reached at a rate of 94.1 μmol·h–1, which was approximately 2.64 times that of the original g-C3N4. Nitrogen defective g-C3N4 had more electrons and stronger H2O molecule adsorption capacity, identified by systematic experiments and DFT calculations. The carboxyl group of fumaric acid reacted with amino group of urea to prevent self-polymerization process of urea and induce nitrogen defects. The changed band structures promoted the absorption of visible light, effective separation of charge, and increased hydrogen evolution driving force. This work will provide a simple and green approach to prepare nitrogen defective g-C3N4 with tunable band structures.

No abstract

The 3D/2D g-C3N4/ZnIn2S4 hollow spherical heterostructure can greatly increase visible light absorption and improve the efficiency of photo-generated electron migration and conversion, resulting in an excellent CO generation rate.

Because of spontaneous agglomeration effect and undesirable electronic state of Zr sites on the surface, zirconium (hydro)oxides generally exhibit suboptimal defluoridation capacity. Herein, a template confinement‐ligand anchoring strategy is developed by utilizing confined growth of zirconium hydroxide (ZH) inside chitosan hydrogel beads (CHB) and subsequent anchoring of fumaric acid (fm) on its surface Zr sites in a monodentate mononuclear coordination mode. This technique leads to uniform dispersion of ultrafine fmZH (≈3.4 nm) and tunable electron density at the Zr sites. Due to the electron‐withdrawing ability of fm, electron‐delocalized Zr sites increase the orbital energy level matching and vacate Zr 4d orbitals to promote hybridization with the F 2p orbitals. Ultimately, robust ZrF bond can be formed as a result of reduced the adsorption energy toward fluoride ions. The defluoridation capacity shows positive linear relationship with the electron extraction ability of ligands. The saturation adsorption capacity and dynamic treatment capacity of CHB@fmZH are 10.8 and 45.9 times higher than that of CHB@ZH, respectively, owing to high electron extraction (0.098 e−) of fm. This study offers a novel insight into the design and synthesis of high‐efficiency metal oxide adsorbents by steering its surface metal sites’ electronic state through ligand effect.