Enhanced Photosensitized Hydrogen Production by Encapsulation of Ferrocenyl Dyes into Single-Walled Carbon Nanotubes

van der Waals one-dimensional atomic crystal heterostructure derived from carbon nanotubes

One-dimensional (1D) van der Waals (vdWs) heterojunctions, due to the dimensional reduction leading to 1D quantum confinement effects and interface effects of the heterojunctions, typically exhibit discrete energy levels and strong electron interactions, resulting in unique conductive and optical behaviors. Carbon nanotube (CNT)-derived 1D atomic crystal vdWs heterojunctions represent a new class of 1D vdWs heterojunctions. They leverage the excellent chemical stability, nanoscale cavities, and adjustable diameters provided by CNTs as templates, ensuring controlled synthesis and precise structural tuning. The 1D radial pathways can alter the photonic-electronic propagation characteristics. At the same time, their unique metal-semiconductor-like electronic structure creates conditions for constructing various types of heterojunctions. The CNTs and their encapsulated 1D materials can lead to synergistic enhancement in the fields of electronics, magnetism, and optics. Currently, research is concentrated on understanding the synthesis mechanisms, integration characteristics, and host-guest interactions, and the exploration of novel 1D atomic crystal vdWs heterojunctions derived from CNTs. This review is focused on the latest progress made in 1D vdWs heterojunctions using CNTs as growth templates, emphasizing the construction methods, selection criteria, and the unique properties and applications arising from these complex interfacial electronic or phonon interactions. We also propose several future directions for the development of CNT-derived 1D atomic crystal vdWs heterojunctions. This review aims to enhance the understanding of their synthesis mechanisms and fundamental properties, broaden the range of available materials, and explore new and broader applications.

A De Novo Auto-Activated Solar-Driven Biohybrid System for Hydrogen Production in Methanotrophic Cells

Climate change driving by greenhouse gas emissions from petroleum-based energy has garnered significant attention. Renewable energy production via a sustainable system that integrates the cell factory and visible-light-driven photocatalysts offers a novel approach for upcycling methane and addressing global energy challenges. Here, an auto-activated biohybrid system driven by solar energy is developed for converting methane into hydrogen fuel, which incorporated thienoviologen (S-MV2+) and genetically engineered methanotrophic bacteria. In this system, S-MV2+ functioned as photosensitizer and electron mediator, capturing solar energy and supplying electrons for an enzyme-catalyzed bioprocess. The genetically modified Methylomicrobium buryatense 5GB1 mutant, lacking methanol dehydrogenase but overexpressing hydrogenase, is able to convert methane into methanol that maintains the electron flow cycle by quenching photogenerated holes for both hydrogen biosynthesis and methane oxidation. Finally, the highest H2 production of 272.96 μM from this biohybrid system was achieved with methanol as a sacrificial agent generated by the H2-producing mutant, resulting in a 140-fold enhancement. This innovative method showcases the potential of coupling photocatalysis with methanotrophic biocatalysis for sustainable energy production. Additionally, the system introduces a new strategy for self-regeneration of sacrificial agents, offering a promising avenue for hydrogen production using greenhouse gases in an eco-friendly manner.

MoSe2-Sensitized Water Splitting Assisted by C60-Dendrons on the Basal Surface

To facilitate water splitting using MoSe2 as a light absorber, we fabricated water-dispersible MoSe2/C60-dendron nanohybrids via physical modification of the basal plane of MoSe2. Upon photoirradiation, the mixed-dimension MoSe2/C60 (2D/0D) heterojunction generates a charge-separated state (MoSe2⋅+/C60⋅-) through electron extraction from the exciton in MoSe2 to C60. This process is followed by the hydrogen evolution reaction (HER) from water in the presence of a sacrificial donor (1-benzyl-1,4-dihydronicotinamide) and co-catalyst (Pt-PVP). The apparent quantum yields of the HER were estimated to be 0.06 % and 0.27 % upon photoexcitation at the A- and B-exciton absorption peaks (λmax=800 and 700 nm), respectively.

Advanced 1D heterostructures based on nanotube templates and molecules

Recent advancements in materials science have shed light on the potential of exploring hierarchical assemblies of molecules on surfaces, driven by both fundamental and applicative challenges. This field encompasses diverse areas including molecular storage, drug delivery, catalysis, and nanoscale chemical reactions. In this context, the utilization of nanotube templates (NTs) has emerged as promising platforms for achieving advanced one-dimensional (1D) molecular assemblies. NTs offer cylindrical, crystalline structures with high aspect ratios, capable of hosting molecules both externally and internally (Mol@NT). Furthermore, NTs possess a wide array of available diameters, providing tunability for tailored assembly. This review underscores recent breakthroughs in the field of Mol@NT. The first part focuses on the diverse panorama of structural properties in Mol@NT synthesized in the last decade. The advances in understanding encapsulation, adsorption, and ordering mechanisms are detailed. In a second part, the review highlights the physical interactions and photophysics properties of Mol@NT obtained by the confinement of molecules and nanotubes in the van der Waals distance regime. The last part of the review describes potential applicative fields of these 1D heterostructures, providing specific examples in photovoltaics, luminescent materials, and bio-imaging. A conclusion gathers current challenges and perspectives of the field to foster discussion in related communities.

An All-In-One Integrating Strategy for Designing Platinum(II)-Based Supramolecular Polymers for Photocatalytic Hydrogen Evolution

Organic polymer photocatalysts have achieved significant progress in photocatalytic hydrogen evolution, while developing the integrated organic polymers possessing the functions of photosensitizer, electron transfer mediator, and catalyst simultaneously is urgently needed and presents a great challenge. Considering that chalcogenoviologens are able to act as photosensitizers and electron-transfer mediators, a series of chalcogenoviologen-containing platinum(II)-based supramolecular polymers is designed, which exhibited strong visible light-absorbing ability and suitable bandgap for highly efficient photocatalytic hydrogen evolution without the use of a cocatalyst. The hydrogen evolution rate (HER) increases steadily with the decrease in an optical gap of the polymer. Among these "all-in-one" polymers, Se-containing 2D porous polymer exhibited the best photocatalytic performance with a HER of 3.09 mmol g-1 h-1 under visible light (>420 nm) irradiation. Experimental and theoretical calculations reveal that the distinct intramolecular charge transfer characteristics and heteroatom N in terpyridine unit promote charge separation and transfer within the molecules. This work could provide new insights into the design of metallo-supramolecular polymers with finely tuned components for photocatalytic hydrogen evolution from water.

Theoretical insights into the spectroscopic properties of ferrocenyl hetaryl ketones

Quantum chemical calculations have been carried out to elucidate the electronic structure as well as to draw structure-property relationships for a series of ferrocenyl hetaryl ketones by means of simulated NMR, IR and UV-vis spectra. In this series, the list of hetaryl groups included furan-2-yl, thiophen-2-yl, selenophen-2-yl, 1H-pyrrol-2-yl and N-methylpyrrol-2-yl. Density functional theory was employed to determine the ground-state properties of the five ketones while their excited-state properties were modeled using a broad range of theoretical methods, namely from time-dependent density functional theory to multiconfigurational and multireference ab initio approaches. The patterns in the ¹³C and ¹⁷O chemical shifts of the carbonyl group were explained by the geometrical twist of hetaryl rings and by the electronic parameters corresponding to π-bonds conjugation and group hardness. Furthermore, the corresponding ¹³C and ¹⁷O shielding constants were analyzed in terms of both their dia/paramagnetic and Lewis/non-Lewis contributions within the framework of natural chemical shielding theory. The pattern in the vibrational frequency of the carbonyl bond was connected with changes in its bond length and bond order. It was established that the electronic absorption spectra of the studied ketones are largely characterized by low-intensity d → π* transitions in the visible region and the dominant high-intensity π → π* transition in the UV region. Finally, the theoretical methods best suited for modeling the excited-state properties of such ketones were designated.

Tailoring biochar for persulfate-based environmental catalysis: Impact of biomass feedstocks

Biochar, a carbonaceous material with engineering potential, has gained attention as an efficient catalyst in persulfate-based advanced oxidation processes (PS-AOPs). Although biomass feedstocks are known as a critical factor for the performance of biochar, the relationship between the catalytic efficiency/mechanism and the types of biomass feedstocks is still unclear. Thus, according to recent advances in experimental and theoretical researches, this paper provides a systematic review of the properties of biochar, and the relationship between catalytic performance in PS-AOPs and biomass feedstocks, where the differences in physicochemical properties (surface properties, pore structure, etc.) and activation path of different sourced biochars, are introduced. In addition, how the tailoring of biochar (such as heteroatomic doping and co-pyrolysis of biomass) affects its activation efficiency and mechanism in PS-AOPs is summarized. Finally, the suitable application scenarios or systems of different sourced biochars, appropriate methods to improve the catalytic performance of different types of biochar and the prospects and challenges for the development of biochar in PS-AOPs are proposed.

Efficient Photoinduced Electron Transfer from Pyrene-o-Carborane Heterojunction to Selenoviologen for Enhanced Photocatalytic Hydrogen Evolution and Reduction of Alkynes

A series of pyrene or pyrene-o-carborane-appendant selenoviologens (Py-SeV²⁺ , Py-Cb-SeV²⁺ ) for enhanced photocatalytic hydrogen evolution reaction (HER) and reduction of alkynes is reported. The efficient photoinduced electron transfer (PET) from electron-rich pyrene-o-carborane heterojunction (Py-Cb) with intramolecular charge transfer (ICT) characteristic to electron-deficient selenoviologen (SeV²⁺ ) (k_ET = 1.2 × 10¹⁰ s^-1 ) endows the accelerating the generation of selenoviologen radical cation (SeV^+• ) compared with Py-SeV²⁺ and other derivatives. The electrochromic/electrofluorochromic devices' (ECD and EFCD) measurements and supramolecular assembly/disassembly processes of SeV²⁺ and cucurbit[8]uril (CB[8]) results show that the PET process can be finely tuned by electrochemical and host-guest chemistry methods. By combination with Pt-NPs catalyst, the Py-Cb-SeV²⁺ -based system shows high-efficiency visible-light-driven HER and highly selective phenylacetylene reduction due to the efficient PET process.

Organic Functionalized Carbon Nanostructures for Solar Energy Conversion

This review presents an overview of the use of organic functionalized carbon nanostructures (CNSs) in solar energy conversion schemes. Our attention was focused in particular on the contribution of organic chemistry to the development of new hybrid materials that find application in dye-sensitized solar cells (DSSCs), organic photovoltaics (OPVs), and perovskite solar cells (PSCs), as well as in photocatalytic fuel production, focusing in particular on the most recent literature. The request for new materials able to accompany the green energy transition that are abundant, low-cost, low-toxicity, and made from renewable sources has further increased the interest in CNSs that meet all these requirements. The inclusion of an organic molecule, thanks to both covalent and non-covalent interactions, in a CNS leads to the development of a completely new hybrid material able of combining and improving the properties of both starting materials. In addition to the numerical data, which unequivocally state the positive effect of the new hybrid material, we hope that these examples can inspire further research in the field of photoactive materials from an organic point of view.

Carbon Nanotube Films for Energy Applications

This perspective article describes the application opportunities of carbon nanotube (CNT) films for the energy sector. Up to date progress in this regard is illustrated with representative examples of a wide range of energy management and transformation studies employing CNT ensembles. Firstly, this paper features an overview of how such macroscopic networks from nanocarbon can be produced. Then, the capabilities for their application in specific energy-related scenarios are described. Among the highlighted cases are conductive coatings, charge storage devices, thermal interface materials, and actuators. The selected examples demonstrate how electrical, thermal, radiant, and mechanical energy can be converted from one form to another using such formulations based on CNTs. The article is concluded with a future outlook, which anticipates the next steps which the research community will take to bring these concepts closer to implementation.

Predicting whether aromatic molecules would prefer to enter a carbon nanotube: A density functional theory study

The interaction of a carbon nanotube (CNT) with various aromatic molecules, such as aniline, benzophenone, and diphenylamine, was studied using density functional theory able to compute intermolecular weak interactions (B3LYP-D3). CNTs of varying lengths were used, such as 4-CNT, 6-CNT, and 8-CNT (the numbers denoting relative lengths), with the lengths being chosen appropriately to save computation times. All aromatic molecules were found to exhibit strong intermolecular binding energies with the inner surface of the CNT, rather than the outer surface. Hydrogen bonding between two aromatic molecules that include N and O atoms is shown to further stabilize the intermolecular adsorption process. Therefore, when benzophenone and diphenylamine were simultaneously allowed to interact with a CNT, the aromatic molecules were expected to preferably enter the CNT. Furthermore, additional calculations of the intermolecular adsorption energy for aniline adsorbed on a graphene surface showed that the concavity of graphene-like carbon sheet is in proportion to the intermolecular binding energy between the graphene-like carbon sheet and the aromatic molecule.

Enhanced Light-Driven Hydrogen-Production Activity Induced by Accelerated Interfacial Charge Transfer in Donor-Acceptor Conjugated Polymers/TiO2 Hybrid

Donor-acceptor (D-A) conjugated polymers have proved to be desired candidates to couple with inorganic semiconductors for enhanced photocatalytic activity. Herein, the matched energy levels between polymer BFB and TiO₂ make them form BFB-TiO₂ composites with moderate photocatalytic H₂ evolution rate (HER). To further enhance the interfacial interaction, BFB was modified with a carboxylic acid end group, which reacted with surface OH of TiO₂ to form an ester bond. As a result, the functionalized BFBA-TiO₂ composites exhibited superior photocatalytic activity. Especially, HER of 4 % BFBA-TiO₂ can reach up to 228.2 μmol h^-1 under visible light irradiation (λ>420 nm), which is about 2.02 times higher than that of BFB-TiO₂ . The enhanced photocatalytic activity originated from the formed ester bond between polymer and TiO₂ , and photogenerated electrons injection from lowest unoccupied molecular orbital (LUMO) of the exited polymer to conduction band of TiO₂ were accelerated. Therefore, based on an intermolecular interaction mechanism, more suitable D-A conjugated polymers with anchoring groups could be designed to couple with other semiconductors for enhancing photocatalytic activity.

Relationships Between Crystal, Internal Microstructures, and Physicochemical Properties of Copper-Zinc-Iron Multinary Spinel Hierarchical Nano-microspheres

Rational design and fabrication of high quality complex multicomponent spinel ferrite with specific microstructures and solar light harvestings toward CO₂ reduction and antibiotic degradation to future energetic and catalytic applications are highly desirable. In this study, novel copper-zinc-iron multinary spinel hierarchical nano-microspheres (MSHMs) with different internal structures (solid nano-microspheres, yolk-shell hollow nano-microspheres, and double-shelled hollow nano-microspheres) have been successfully developed by a facile self-templated solvothermal strategy. The morphology and structure, optical, as well as photoinduced redox reactions including interfacial charge carrier behaviors and the intrinsic relationship of structure-property between intrinsic nano-microstructures and physicochemical performance of copper-zinc-iron ferrite MSHMs composites were systematically investigated with the assistance of various on- and/or off- line physical-chemical means and deeply elucidated in terms of the research outcomes. It is demonstrated that the modification of the interior microstructures can be applied to tune the catalytic properties of multinary spinel by tailoring the temperature programming to fine control the two opposite forces of contraction (Fc) and adhesion (Fa). Among various internal microstructures, the obtained double-shelled copper-zinc-iron MSHMs exhibited the superior catalytic performance toward 8.8 and 38 μmol for H₂ and CO productions as well as 80.4% removal of sulfamethoxazole antibiotics. As evidenced from primary characterizations, for example, combined steady-state PL, ns-TAS, and Mössbauer and sequential investigations, the remarkable improvements in the catalytic activity can be primarily attributed to several crucial factors, for example, the more effective e^--h⁺ spatial separations and interfacial transfers, multiple internal light scattering, higher photonic energy harvesting and effective reactive oxygen species generation with long radical lifetimes. The current research provides new insights into the molecular design of novel copper-zinc-iron multinary spinels and the intrinsic relationship of structure-property between interior structures (e.g., different crystal texture, morphologies structures) and the physicochemical performance of the aforementioned multinary spinels.