Effect of Mie resonance on photocatalytic hydrogen evolution over dye-sensitized hollow C-TiO2 nanoshells under visible light irradiation

Morphology design and electronic configuration of MoSe2 anchored on TiO2 nanospheres for high energy density sodium-ion half/full batteries

Molybdenum selenide (MoSe2) has shown potential sodium storage properties due to its large layer spacing (0.646 nm) and high theoretical capacity and narrow band gap. However, as the anode material of sodium ion batteries (SIBs), the MoSe2's performance is not ideal, especially due to the layer agglomeration and stacking caused by volume expansion and low intrinsic conductivity. Hence, morphology design and electronic configuration of MoSe2 is proposed via building MoSe2 nanosheets and auxiliary sulfur doping on the surface of the TiO2 hollow nanosphere (S-MoSe2@TiO2). The hierarchical shaped S-MoSe2@TiO2 effectively overcomes the shortcomings of high surface energy and weak interlayer van der Waals force of MoSe2. As anode for SIBs, S-MoSe2@TiO2 delivers enhanced cycling life and rate capability (308 mAh/g at 10 A/g after 1000 cycles) with the comparison of MoSe2@TiO2 or pure MoSe2 and TiO2. Such excellent sodium storage performance is due to the fast diffusion kinetics of Na+. When it is applied in sodium ion full batteries, the S-MoSe2@TiO2 anode based cell can reach a high energy density of 187.8 W h kg-1 at 148.3 W kg-1. The design of the new MoSe2-based hybrid provides a novel scheme for the preparation of advanced anode in SIBs.

Boosting photocatalytic H2 evolution on UIO-66-NH2/covalent triazine-based frameworks composites by constructing a covalent heterojunction

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have been proved as efficient catalysts for photocatalytic hydrogen (H2) evolution, thanks to their tunable functionalities, permanent porosity, excellent visible light response, and physicochemical stability. Herein, a series of photocatalysts (termed NUBC) was fabricated by loading different amounts of Zr-UiO-66-NH2 (NU) onto a benzoic acid-modified covalent triazine-based framework (BC) based on post-synthetic covalent modification. The resulting NUBC catalysts exhibited a type-II Z-scheme heterojunction structure formed via the amide covalent bonds between the amine groups on NU and carboxyl groups on BC. The optimal loading of NU on BC is 30 wt.% (30NUBC) and the corresponding photocatalytic H2 evolution rate was 378 μmol h-1 g-1, almost 445 and 2 times than that of NU and BC, respectively. The synergistic effect between the type-II Z-scheme heterojunctions and amide bonds was conducive to boosting visible light harvesting and facilitating charge transportation and separation. Furthermore, the prepared NUBC catalysts show great reusability and stability. Overall, this work sheds light on the design of novel MOF/COF hybrid materials and provides a systematic exploration of their photocatalytic H2 evolution properties.

Integrating Co(OH)2 nanosheet arrays on graphene for efficient noble-metal-free EY-sensitized photocatalytic H2 evolution

The development of an efficient noble-metal-free cocatalyst is the key to photocatalytic hydrogen production technology. In this study, hierarchical Co(OH)2 nanosheet array-graphene (GR) composite cocatalysts are developed. With Eosin Y (EY) as a photosensitizer, the optimal Co(OH)2-10%GR hybrid cocatalyst presents excellent photocatalytic activity with an H2 production rate of 17 539 μmol g-1 h-1, and the apparent quantum yield for hydrogen production can reach 12.8% at 520 nm, which remarkably surpasses that of pure Co(OH)2 and most similar hybrid cocatalyst systems. Experimental investigations demonstrate that the excellent photocatalytic activity of Co(OH)2-GR arises from its unique nanosheet array architecture, which can collaboratively expose rich active sites for photocatalytic hydrogen evolution and facilitate the migration and separation of photogenerated charge carriers. It is desired that this study would supply a meaningful direction for the rational optimization of the constitute and structure of cocatalysts to achieve efficient photocatalytic hydrogen generation.

Limbic Inducted and Delocalized Effects of Diazole in Carbon Nitride Skeleton for Propelling Photocatalytic Hydrogen Evolution

Skeleton modification on carbon nitride (g-C₃N₄) via organic molecules is a recognized effective strategy to improve photocatalytic performance because it can powerfully improve charge separation in the skeleton plane. Herein, a diazole with a unique conjugated structure is bonded on edge of the g-C₃N₄ skeleton through a moderate polymerization of urea with 4-aminoantipyrine (4AAP). Meanwhile, the Pt nanoparticles selectively deposit on edge of the g-C₃N₄-4AAP₁₅ nanosheet. It reveals that the robust limbic inducted and delocalized effects of diazole not only facilitate photogenerated electrons aggregation toward skeleton edge to promote in-plane carrier separation but also effectively stabilize and delocalize photogenerated electrons to improve carrier lifetime for propelling the photocatalytic hydrogen evolution (PHE) reaction. Specifically, the PHE rate over optimal g-C₃N₄-4AAP₁₅ (284.2 μmol h^-1) is 10 times that of pure g-C₃N₄ (27.6 μmol h^-1) and the apparent quantum efficiency (AQE) at 420 nm reaches up to 24.2%. Through insights into the functionalized effect of small nitrogenous heterocycles introduced into the skeleton edge of g-C₃N₄, this work opens a new design thought for exploiting high-efficiency g-C₃N₄-based photocatalysts for photocatalytic application.

Simultaneous photocatalytic degradation of ibuprofen and H2 evolution over Au/sheaf-like TiO2 mesocrystals

Considerable effort has been devoted to the efficient degradation of pharmaceuticals and personal care products (PPCPs), while the chemical energy in these processes has been widely overlooked. In this study, we demonstrated the simultaneous hydrogen production and ibuprofen degradation through heterogeneous photocatalysis. By anchoring Au nanoparticles (NPs) on the (101) surface of sheaf-like TiO₂ mesocrystals with [001] orientation, efficient charge separation is achieved, which is essential for the photocatalytic redox reactions. XPS analysis showed that the binding energies of Ti 2p and O 1s indicated no shift after Au addition. Peaks observed at 81.8 and 85.5 eV due to Au 4f_7/2 and Au 4f_5/2 of metallic gold on the surface of Au/meso-TiO₂, confirmed the formation of Au NPs. The as-synthesized anatase TiO₂ mesocrystals are composed of small nanocrystals with a size of 8 nm and exhibit the uniform sheaf-like morphology along [001] orientation. As expected, the 1 wt% Au/TiO₂ mesocrystals shows the largest photocurrent density, highest H₂-evolution rate, and fastest photodegradation rate of ibuprofen under simulated sunlight irradiation among all the studied catalyst. Furthermore, the effect of solution pH, common anions (Cl^-, NO₃^-, and SO₄^2-) and cations (Na⁺, K⁺, and Ca²⁺) on photocatalytic H₂ evolution and degradation of ibuprofen were individually investigated and discussed. A mechanism for the simultaneous photocatalytic hydrogen generation and degradation of ibuprofen has also been proposed. This work opens up new opportunities for the development of energy efficient techniques for PPCPs degradation.