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Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists. In this work, it is demonstrated that the COF-TpPa with keto-enol tautomerism equilibrium structure shows excellent performance (yield>99% after 8 h) in the selective photocatalytic oxidative coupling of amines to imines under visible light irradiation. It is revealed that three kinds of reactive oxygen species (superoxide radical, hydroxyl radical and singlet oxygen) participate in this photocatalytic oxidation reaction. In addition, hydrogen protons cleaved from the benzyl are proven to be reduced to hydrogen in the conduction band of COF-TpPa in anaerobic atmosphere, accompanied with the formation of imines. The direct hydrogen evolution from amine provides an effective way to extract clean energy from organic molecule as well as the production of value-added chemicals. As a contrast, COF-LZU1 with similar structure and chemical composition to COF-TpPa but without keto-enol tautomerism exhibits worse optical properties and photocatalytic performance. It is also demonstrated that keto-enol tautomerism favors the adsorption of benzylamine based on the characterization results and theoretical calculations.

Compared with pristine phase change materials (PCMs), nanopore-based composite PCMs generally have significant differences in thermophysical properties due to the nanoconfinement effect. However, experimental data are difficult to accurately reveal the microscopic molecular interaction mechanism between PCMs and nanoporous supporting materials. To overcome this difficulty, we systematically explored the molecular interactions between C18-PCM molecules with different functional groups (stearic acid, octadecanol, octadecylamine and octadecane) and methyl-modified carbon nanotubes (CNTs), and analyzed the spatial distribution and thermal characteristics of C18-PCM molecules in the pores of CNTs using molecular dynamics simulations. Molecular insights into the microscopic interaction mechanism between C18-PCM molecules and nanoporous CNTs were comprehensively proposed at the molecular scale. These constructive understandings provide meaningful theoretical references for the targeted construction of high-performance CNT-based composite PCMs for thermal storage applications.

Carbon -MoS2−x@CdS (C-MoS2−x@CdS) core-shell nanostructures with controlled surface sulfur (S) vacancies were prepared via a glucose assisted hydrothermal growth method. The glucose acted as a reducing agent of C-MoS2−X to partially reduce Mo4+ ions to Mo3+ and served as a carbon source to insert the amorphous carbon into the layered MoS2−X simultaneously. The presence of Mo3+ result in the surface S-vacancies, which can provide more additional active sites and enhance the photocatalytic performance. Moreover, the inserted carbon in layered MoS2−X enhanced the electron mobility and decreased the resistance electron transfer. Density functional theory (DFT) calculation confirmed that the surface S-vacancies and the amorphous carbon increase the projected density of states at the conduct band edge, which could enhance the photo-absorption and photo-responsibility. The result is consistent with the photocatalytic H2 production experiment. C2-10%MoS2−x@CdS presented a high H2 evolution rate of 61,494 μmol h−1 g−1 under visible light irrigation (λ ≥ 420 nm), which is 1.98 times and 158 times higher than that of sample without S-vacancies (10%MoS2@CdS) and pure CdS, respectively.

Interfacial conjugation was employed to engineering preparation of TiO2@NH2-MIL-101(Fe) heterojunction photocataysts through carboxylate bidentate linkage with TiO2 and NH2-MIL-101(Fe), which can enhance the electron transfer capability from metal-organic frameworks (MOFs) to TiO2 and photocatalytic activity. The carbon nanospheres derived from glucose act as reducing agent and template to synthesize oxygen vacancies TiO2 hollow nanospheres. Then, the oxygen vacancies were employed as antennas to connect 2-aminoterephtalic acid as bidentate carboxylate chelating linkage on TiO2, which have been proved by the density functional theory (DFT) calculations. Subsequently, NH2-MIL-101(Fe) was coordinatingly formed on the surface of TiO2. The conjugation effects between TiO2 and NH2-MIL-101(Fe) enhanced the electron transfer capability and could also induce the band tail states to narrow bandgap of the composites. Thus, the photodegradability of methylene blue was remarkably enhanced under visible light irradiation. The degradation rate of TiO2@17%NH2-MIL-101(Fe) was 0.131 min−1, which was about 3.5 and 65 times higher than that of NH2-MIL-101(Fe) and TiO2, respectively.

Conventional single thermal nature of phase change materials (PCMs) seriously obstructs their frontier applications. Herein, we designed advanced carbon nanotube (CNT) bundles assembled flexible hierarchical framework based phase change material composites for high-performance thermotherapy of allergic rhinitis. Hierarchically interconnected 3D freestanding flexible CNT sponge was constructed via a facile organic solvent-free route using table salt as a sacrificial template. The resulting hierarchical CNT sponge serves as an ideal compatible supporting host and polyethylene glycol (PEG) serves as an excellent thermal energy guest. Subsequently, we designed advanced portable integrated functional mask consisting of outer air purification layer and inner thermal regulation layer for the thermotherapy of allergic rhinitis, in which pristine CNT sponge serves as an excellent particulate matter capturer and PEG-infiltrated CNT sponge serves as a superior thermal regulator. Strikingly, our uniquely constructed flexible CNT sponge-involved composite PCMs assisted by polyvinylidene fluoride (PVDF) harvest high-performance thermotherapy (~33 ​min of the plateau at ~43.5 ​°C). The corresponding medical results (HE staining and Wrights staining) further indicate that our designed thermotherapy mask can significantly reduce the inflammatory injury of nasal mucosa. Additionally, pristine hierarchical CNT sponge guarantees the inhaled air quality and enhances the thermotherapy effect. This synthetic strategy can be scaled up for large-scale production. This novel functional host-guest strategy creates an innovative platform for developing advanced multifunctional PCMs with multiple fascinating peculiarities and desired functional properties and teaches an old dog new tricks.

Owing to the high abundance, good conductivity and excellent tolerance to harsh environment, carbon host materials have recently attracted considerable research interest in the fields of electrochemical hydrogen evolution reaction (HER). However, the deficiency of intrinsic active sites within the carbon host materials substantially gives rise to an inferior HER performance. In this work, atomically dispersed ruthenium active sites are deliberately introduced into the carbon host structure by controlled pyrolysis of Ru-doped ZIF-8. With atomic Ru sites on a unique whisker-like secondary microstructure and a favorable porous texture, the optimal product exhibits a high intrinsic activity as well as robust durability, which especially outperforms the Pt/C benchmarking in alkaline media. A combination of control experiments and theoretical calculations demonstrates that atomically dispersed Ru sites within the carbon host matrix serve as the dominant catalytically active sites, and remarkably optimize the free energy of water molecule dissociation during the Volmer step, thus boosting the HER performance.

Two-dimensional (2D) metal-organic frameworks (MOFs) are promising materials for catalyzing the oxygen evolution reaction (OER) due to their abundant exposed active sites and high specific surface area. However, how to rapidly screen out highly-active 2D MOFs from numerous candidates is still a great challenge. Herein, based on the high-throughput density functional theory (DFT) calculations for 20 kinds of different transition metal-based MOFs, we propose a factor for fast screening of 2D MOFs for the OER under alkaline conditions (pH = 14.0), that is, when the Gibbs free energy change of the O-O bond formation (defined as Δ

The oxidation of mercaptans under mild and base-free conditions is of vital importance in terms of economy and environment for petroleum processing industry. Here, we developed a series of MOF-derived cobalt-based nitrogen-doped (N-doped) carbon (Co/CN-x) catalysts for the base-free catalytic oxidation of mercaptans. The optimal Co/CN-900 showed excellent catalytic activity for the oxidation of mercaptans under base-free conditions, yielding complete conversion of various mercaptans and > 99.0% selectivity of disulfides. The high performance can be contributed to the advantages of hierarchical pore structure for the diffusion and migration of substrates, self-carrying alkalinity for the formation of mercaptide anion, abundant active Co sites for catalytic oxidation of mercaptans as well as the synergistic effects between the Co nanoparticles (NPs) and N-doped carbon supports. Furthermore, a possible mechanism for base-free catalytic oxidation of mercaptans over Co/CN-x catalysts is proposed based on a set of control experiments and density functional theory (DFT) calculations.

Fully releasing the thermal storage capacity of Phase change materials (PCMs) requires the integration of surface functionalization and nanoconfinement effect and therefore ingenious design of the pore size and surface property of supports. Herein, this work thoroughly explores the influence of synergistic coupling between nanoconfinement effect and interfacial hydrogen bonding strength from the carriers and the core materials on the crystallization behavior of C18 PCMs molecules. Rejoicingly, the fusion enthalpy of octadecanol/NH2-LP-SBA-15-CH3 composite can be as high as 186.08 J/g, which is much higher than those of other composite PCMs. The interfacial interaction plays a dominant role in the crystallization of C18 PCMs in large nanopores (e.g., 6.79 ~ 12.55 nm), hence the more suitable hydrogen bond strength between the supports and C18 may be advantageous to trigger the nucleation of more molecular chains. However, the decisive factor for the crystallization of C18 PCMs will be converted to nanoconfinement effect in small nanopores (e.g., 2.53 ~ 3.78 nm). Density functional theory (DFT) calculations are employed to propose atomic-level surface interactions. The obtained shape-stable composite PCMs exhibit excellent chemical compatibility, ultrahigh thermal stability, elevated thermal conductivity and outstanding cyclability, which are important prerequisites for the fascinating energy storage system.

A novel and facile post-grafting strategy, via a Schiff base chemical reaction between aldehyde and −NH2 groups within NH2-MIL-125(Ti) has been developed to construct aromatic heterocycle-grafted metal organic frameworks (MOFs) photocatalysts. The improved conjugated system in MOFs showed lower band gaps and their excellent catalytic activities were manifested by selective oxidation of alcohols to corresponding aldehydes under visible light irradiation with high conversion and selectivity. Density functional theory (DFT) was applied for simulating the band gaps and electron orbits of heterocycle-grafted MOFs. The post-synthetic aromatic heterocycles in the MOFs network did not influence the original framework, but effectively expanded its π-delocalized system and promoted the separation and transfer of photo-excited charge carriers. As a result, the aromatic heterocycle-grafted MOFs exhibit significantly enhanced visible-light photo-catalytic activity for selective oxidation of alcohols over pristine NH2-MIL-125(Ti). Especially, the NH2-MIL-125(Ti) grafted by 2-quinolinecarboxaldehyde and 3-thiophenecarboxaldehyde showed better performance (more than 85% conversion of benzyl alcohol) due to the excellent photon adsorption and charge carriers transfer of aromatic heterocycles grafted on MOFs. This general grafting strategy can be utilized to graft large numbers of aromatic rings with different molecular structures onto NH2-MIL-125(Ti).

Synthesis of high-performance electrocatalysts is significant for energy conversions. The oxygen evolution reaction (OER) is a fundamental process in such energy conversions. Here, we first report the synthesis of NiFe-bimetal two-dimensional (2D) ultrathin metal-organic frameworks (MOFs) nanosheets (NiFe-UMNs) with a uniform thickness of ~10 nm, which show excellent catalytic activity for OER in alkaline conditions. The as-prepared NiFe-UMNs can deliver the current density of 10 mA cm−2 at a low overpotential of 260 mV. Moreover, NiFe-UMNs possess by far the lowest Tafel slope of 30 mV dec−1 for OER. The high-performance activity is the result of abundant surface coordinatively unsaturated metal atoms, as well as the addition of Fe that is also crucial to enhance the activity.

A dual-Z-scheme heterojunction consisting of WS2-WO3·H2O and g-C3N4-WO3·H2O was prepared through coupling partially oxidized WS2 with g-C3N4. The suitable band matching among WS2, WO3·H2O and g-C3N4 realize the directional separation of electrons and holes from g-C3N4 to WS2 and WO3·H2O respectively, and the holes of WS2 are also quenched with electrons of WO3·H2O in the WS2-WO3·H2O heterostructure. Thereby, photogenerated carrier recombination is efficiently suppressed, and a strong reducibility of WS2-WO3·H2O/g-C3N4 catalyst is stabilized. The WS2-WO3·H2O nanodots with a tight contact provide a short diffusion channel to facilitate the rapid migration of the g-C3N4 carriers from the vicinity of the cocatalyst to the target reaction sites, further, the active sites of WS2 edges are heavily exposed to improve the H2 evolution rate. Benefiting from such a dual-Z-scheme heterojunction, the optimized dual-Z-scheme WS2-WO3·H2O/g-C3N4 catalyst shows a high H2 evolution rate (1276.9 μmol h−1 g−1), which is 57 times higher than that of the original g-C3N4. This work raises a new design approach for heterostructure photocatalyst and provides a valuable reference for future research of photocatalytic H2 production.

Selective oxidation of saturated C H bonds to value-added chemicals under mild conditions is of great importance in chemical community. In this work, conjugated polymer (PMPTA) coated MIL-125(Ti) composites with type I heterojunction structure were obtained from the mixture of MIL-125(Ti), melamine and terephthalaldehyde via a solvent-free hydrothermal method. The MP-30 with optimal composition has excellent photocatalytic activity for the selective oxidation of benzylic C H bonds to their corresponding aldehydes and ketones under the illumination of 420 nm light using O2 as oxidant and N-Hydroxyphthalimide (NHPI) as co-catalyst. The conversions of fluorene catalyzed by MIL-125(Ti) and PMTPA are 32% and 65%, respectively, while the conversions of fluorene over MP-20, MP-30 and MP-40 are significantly improved, which are 86%, 99% and 77%, respectively. The characterization results from photoluminescence spectroscopy, photocurrent and band gap positions demonstrate that the one-way transfer of electrons and holes between the MIL-125(Ti) and PMTPA through the heterojunction structure allows the substrate to react rapidly on the outer layer of heterostructured MIL-125(Ti)/PMTPA, resulting an increase in photocatalytic efficiency. Moreover, the introduced heterojunction structure reduces the recombination of photo-generated electrons and holes and improves the efficiency of the conversion of holes into reaction intermediates.

Carbon -MoS

Regulation of the electronic structure of metal oxo clusters in metal organic frameworks (MOFs) is a promising way to modulate charge transfer efficiency and photocatalytic performance. Herein, a series of Ni2+ doped NH2-MIL-125-Ti (NH2-MIL-125-Nix/Ti) with different Ni2+/Ti4+ molar ratio (x = 0.5%–1.5%) are prepared via an in-situ doping method. Correlations between the electronic structure of (Ti/Ni)8O8(OH)4 nodes and charge transfer efficiency, bandgap and energy position of band edges of the NH2-MIL-125-Nix/Ti are systematically investigated based on experimental and computational method. The doped Ni2+ was confirmed to be an efficient mediator to promote the electron transfer from photoexcited terephthalate ligand to the (Ti/Ni)8O8(OH)4 nodes in NH2-MIL-125-Nix/Ti. The NH2-MIL-125-Ni1%/Ti exhibited the highest CO2 conversion rate with 98.6% CO selectivity and the factors affecting the photocatalytic CO2 reduction performance are also studied. It provides some guidance for developing MOFs photocatalyst with targeted performance via modification of the electronic structure of metal oxo clusters.

Hybridization of Metal-Organic frameworks (MOFs) with conductive materials has proven to be an efficient way to enhance their oxygen evolution reaction (OER) performance. Here we present a novel primer-induced in situ hybridization method to covalently link the nickel-based two-dimensional (2D) ultrathin MOFs nanosheets and graphene. By considering the energetically favorable anchoring process, thermodynamically prohibited self-polymerization side reaction and high delocalization of lowest unoccupied molecular orbitals (LUMO), the optimal phenylenebisboronic acid (PBA) primer were rapidly identified by screening thousands of primers via a high-throughput periodic density functional theory (DFT) workflow. Aided by the computational results, the PBA molecules were used to be covalently bonded to graphene successfully and then induce the in-situ growth of ultrathin Ni-MOFs nanosheets with terephthalic acid (TPA) as the ligand (denoted as Ni-HMOF@GE-PBA). The as-prepared Ni-HMOF@GE-PBA was demonstrated as a high-performance electrocatalyst for OER, delivering a much lower onset potential than that of simple blending of graphene and Ni-MOFs nanosheets by 150 mV. This design and construction strategy would pave an efficient pathway to rapid exploration and synthesis of new 2D–2D hybrid catalytic materials with excellent performance for OER.