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The replacement of the oxygen evolution reaction with a higher valuable oxidation process can overcome the sluggish kinetics to promote renewable hydrogen production, simultaneously achieving energy storage and environmental protection. However, the effective integration of two redox half-reactions in one photocatalytic reaction system is still a challenge. Here the p-diethynylbenzene and dibenzothiophene sulfone copolymer (PEB-DBT) is well-designed to couple with α-Fe2O3via a palladium-catalyzed Sonogashira cross-linking reaction, forming a heterojunction with strong interfacial interaction. In particular, there is a different preferred charge transfer path of PEB-DBT/α-Fe2O3via modulating the work function difference in various solutions. The results suggest that the Z-scheme electron transfer pathway is predominant in triethanolamine (TEOA) and ofloxacin (OFL) solutions, instead of the type-II heterojunction that forms in H2O or methylene blue (MB). The Z-scheme PEB-DBT/α-Fe2O3 heterojunction has excellent performance in the hydrogen evolution half-reaction and OFL degradation, which is about 2.7 times and 3.3 times higher than that of pure PEB-DBT, respectively. Finally, it successfully achieved simultaneous photocatalytic H2 evolution and OFL degradation under visible light. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) simulations were performed to study the effects of structure, interaction and mechanical properties of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/benzotrifuroxan (CL-20/BTF) under a hydrostatic pressure in the range of 0–100 GPa. The calculated structure agrees well with the experimental data at ambient pressure and 293 K. The CL-20/BTF cocrystal exhibits an anisotropic compression behavior, as shown by the change in lattice constants with pressure, because it is more difficult to compress along the b-axis. In addition, the band gap values decrease rapidly from 0 GPa to 40 Gpa and then decrease slowly with pressure increasing from 50 GPa to 100 GPa. Furthermore, the analysis of the active bond reveals that two types of O–N bonds in the furoxan group and four types of N–N bonds in CL-20 have significant responses to pressure. The Hirshfeld surface gives an insight into intermolecular interaction, and combining the analysis of the Hirshfeld surface and two-dimensional fingerprint plots shows that intermolecular interaction mainly comes from hydrogen bonding interactions and NO2–π interaction in CL-20/BTF cocrystal. According to the stronger intermolecular interaction (sum of O⋯H/H⋯O, N⋯H/H⋯N, O⋯N/N⋯O and O⋯O) decreasing with increasing pressure, it can be speculated that the impact sensitivity of CL-20/BTF increases as the pressure increases. The mechanical properties reveal that this cocrystal shows an increase in ductility, deformation resistance and stiffness with increasing pressure. The elastic anisotropy indicates that the CL-20/BTF varies anisotropically under pressure in the range of 0–100 GPa but is near isotropy level under 20 GPa. [ABSTRACT FROM AUTHOR]

The development of novel catalysts to regulate product selectivity and insight into the mechanism of lignin hydrogenolysis are important for the comprehensive utilization of lignocellulose. Herein, we present a non-precious bimetallic catalyst Ni5Fe5/Al2O3 with improved catalytic performance relative to commercial Pd/C and Ni10/Al2O3 for hydrogenolysis of woody sawdust. In particular, the selectivity of propylguaiacol and propylsyringol is 79.1%. We developed kinetic experimental studies on β-O-4 model compounds and directly monitored the coniferyl alcohol or sinapyl alcohol intermediates in the reaction system for the first time. This directly demonstrates the lignin hydrolysis reaction pathway with simultaneous breakage of Cα-OH and Cβ-O. In the catalytic system, the reason for the difference in selectivity between Ni5Fe5/Al2O3 and other catalysts is their different hydrogenation pathways for intermediates coniferyl alcohol or sinapyl alcohol. Our work provides both an efficient catalyst and insight into understanding and regulating the mechanism of lignin hydrogenolysis. [ABSTRACT FROM AUTHOR]

CO2 reduction reactions (CO2RRs) are considered as one of the most potential strategies to realize the effective capture and conversion of CO2, which can not only reduce the globally accelerating CO2 emission but also generate high-value-added products. In this study, the electronic structure of transition metal atom-doped Mo2C (TM-Mo2C), CO2 adsorption, activation and the performance for CO2 reduction into CH4 were investigated by density functional theory. Spontaneously CO2 capture and activation abilities were observed in TM-Mo2C electrocatalysts due to the enhanced interaction between CO2 and Mo-3d/TM-3d orbitals. TM doping can increase the interaction between CHOH/CH2O and active sites, and decrease spin up and down integrated-crystal orbital Hamilton population (ICOHPspinup and ICOHPspindown). Thus, TM doping promotes the adsorption of CHOH/CH2O and decreases the Gibbs free energies of *CHO → *CHOH (ΔG*CHO→*CHOH) and *CHO → *CH2O (ΔG*CHO→*CH2O) reaction steps, in which ΔG*CHO→*CH2O of Co/Cu/Cr/Mn/Ni-Mo2C has a linear relationship with ICOHPspinup and ICOHPspindown. Moreover, the limiting potentials (UL) are −0.58, −0.69, −0.38, −0.67, and −0.61 for Co/Cu/Cr/Mn/Ni-Mo2C, respectively, which are not only more positive than that of pure Mo2C (UL = −1.35 eV) but also equal to or more positive than that of the reported Cu (−0.81 and −0.60 eV) catalyst. Our present results provide not only reference for the enhanced CO2RR performance of Mo2C with TM doping but also primary insights into the relationship between the spin up/down anti-bonding states filling and the reaction rate of CHO conversion into CH2O. [ABSTRACT FROM AUTHOR]

Modifying the backbone, side chains and end groups of non-fullerene acceptors (NFAs) in organic photovoltaics (OPVs) can tune their properties and impact performance. Hence, understanding how different functional groups influence properties and performances is critical for developing novel NFAs for OPVs. Herein, to investigate the effects of introducing methyl groups and substituting dicyano with O, based upon extensive quantum chemistry calculations, we selected a PM6:IT-4F heterojunction as the reference system and studied the geometries, electronic structures, excitation properties, and electrostatic potentials (ESPs) of PM6, IT-4F, IM-4F, and IO-4F as well as PM6:IT-4F, PM6:IM-4F, and PM6:IO-4F complexes as interface models. The rate constants of the charge transfer (CT), exciton dissociation (ED), and charge recombination processes at the heterojunction interface were also calculated. The results indicated that the superior performance of PM6:IM-4F and PM6:IT-4F systems could be ascribed to the redshift of optical absorptions that assure more photon harvest, larger ESP difference between PM6 and NFAs, and larger excitation energy difference between NFA's local excitation and CT that is favorable for efficient ED. However, the larger open-circuit voltage of PM6:IO-4F OPV results from the substitution of dicyano with O, causing a significant increase in the lowest unoccupied molecular orbital and CT excitation energies of PM6:NFA complexes, whereas the smallest short-circuit current density is mainly related to less CT excitations, blue-shift optical absorption that is not complementary with that of PM6, inefficient ED, and the smaller ESP difference between PM6 and IO-4F. [ABSTRACT FROM AUTHOR]

Single-atom catalysts with magnetic elements as the active center have been widely exploited as efficient oxygen evolution reaction (OER) electrocatalysts. Here, different contents of transition metal atom Mn adsorbed on graphitic carbon nitride (g-C3N4) were investigated for OER properties by first-principles calculations. Based on the Gibbs free energy, 2Mn–C3N4 possesses higher OER properties, and has a lower over-potential (1.22 V) than Mn–C3N4 (2.42 V). 2Mn–C3N4 has moderate absorption energies for OH and OOH, which benefits the first one-electron reaction and the O2 desorption during the OER. Additionally, by analyzing the partial density of states and projected crystal orbital Hamilton population, the anti-bonding states become less occupied and the adsorption strength of OH is enhanced in 2Mn–C3N4. Thus, the adsorptive strength of 2Mn–C3N4 for OH is stronger than that of Mn–C3N4, which causes 2Mn–C3N4 to show a higher OER activity. The metal–support interaction can alter the local electronic characteristics. The interaction between the metal active center and the reaction intermediates can influence the OER performance, where the specific orbital hybridization plays an important role. Therefore, our results provide a primary understanding of the influence of orbital hybridization intensity on effective OER catalysts. [ABSTRACT FROM AUTHOR]

In order to reveal the correlation effect on the electronic properties in particular 5f electron occupation numbers of Pu/U ions in a (Pu,U) mixed oxide-PuUO4, a first principles calculation is performed by using density functional theory (DFT) plus a dynamical mean field theory (DMFT) scheme with the spin–orbit coupling (SOC) and on-site Coulomb repulsion for correlation effect due to localized Pu/U 5f orbitals. Results demonstrate that Pu/U 5f electron occupation numbers in the ground state of PuUO4 are mainly composed of 5f4/5f5 and 5f2/5f3 configurations, and exhibiting the intermediate occupation (IO) numbers with average 5f occupation numbers of about nf = 4.879 and 2.423 for Pu and U ions, respectively, irrespective of different Pu and U lattice sites in PuUO4. Pu 5f j = 5/2 and j = 7/2 components are in moderately and weakly correlated states, respectively, while U 5f j = 5/2 and j = 7/2 manifolds are both in weakly correlated states. jj and LS coupling schemes are feasible for Pu and U 5f electrons, respectively. In order to directly compare with the experimental angle-resolved photoemission spectrum (ARPES), we also estimate the momentum-resolved electronic spectrum function for this system. [ABSTRACT FROM AUTHOR]

The industrialization of perovskite solar cells (PSCs) is based on the development of efficiency and stability. Here, a composite film of a polyethylenimine ethoxylated (PEIE) and tellurophene-based two-dimensional metal–organic framework (2D MOF) was introduced to realize the nondestructive passivation of TiO2. This interfacial layer can not only realize the effective passivation of TiO2, but can also further improve the morphology of the perovskite film. After the modification of the PEIE-2D MOF composite film, the morphology and crystallinity of the perovskite film are greatly optimized, the trap states in the TiO2 layer are reduced, and the electron transport in the device is enhanced, thus finally achieving highly efficient and stable FA0.25MA0.75PbI3 PSCs with a maximum efficiency of 22.22%. It was demonstrated that the reduced trap states and the smooth surface of the TiO2 electron transport layer are the reasons for the high performance of modified PSCs. This method provides a new way for improving the interface state to achieve highly efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

Methylcyclopentadiene dimer and trimer based fuels are synthesized from 5-methyl furfural for the first time with yields as high as 74.4%. They exhibit both high density and high thermal stability that are better than those of widely used fossil based jet fuels such as JP-10 and JP-7, and represent types of high-performance fuels. This work also provides a potential and scale-up feasible route for synthesizing high-performance jet fuels from biomass. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT)-supported Ni-modified MoS2 catalysts with ultra-high loading were synthesized with the assistance of citric acid. The morphology of the nanoflake arrays could be controlled to give abundant stepped sites, which favored the hydrogenation desulfurization pathway of dibenzothiophene. The catalyst exhibited excellent performance and stability for hydrodesulfurization of model oil and coal-to-liquid fuel. [ABSTRACT FROM AUTHOR]

The major challenge in the synthesis of high-density biofuels is to identify the bio-based source for C–C cyclic compounds and C–C coupling reactions with a suitable selectivity. Herein, we selectively synthesize 1,2,4-benzenetriol (BTO) with a yield of 51.4% from cellulose-derived 5-hydromethylfurfural via a ring-rearrangement reaction. The cellulose-derived route is a more meaningful route for the C–C cyclic compounds compared to the traditional hemicellulose- and lignin-derived routes. Furthermore, BTO is very easily dimerized via a C–C oxidative coupling reaction, showing a yield of 94.4% and selectivity of nearly 100% under environmentally friendly reaction conditions. After hydrodeoxygenation, bicyclohexane is obtained with a yield of 87.4%. This work not only provides a promising route to produce C–C cyclic fine compounds based on a cellulose-derived route, but also shows a highly efficient synthesis route for high-density biofuels via the C–C oxidative coupling reaction. [ABSTRACT FROM AUTHOR]

Herein, novel green synthetic routes to 4-hydroxy-2-cyclopentenone (HCP) and 2-cyclopentenone (CPE) from biomass-derived furfuryl alcohol via double-metal cyanide catalysis are proposed. For the synthesis of HCP, in comparison to conventional solid acids (i.e., Amberlyst-15), MOFs with coordinatively unsaturated metal ions as pure Lewis acid sites exhibit advantageous catalytic selectivity in the reaction under an N2 atmosphere in a bi-phasic water/n-hexane solvent system. FeZn and FeZn-P result in an HCP yield of 77.4% and 88.2%, respectively. For the CPE synthesis, the reaction conditions are the same as those for HCP, except a mono-phasic water solvent system and H2 atmosphere were employed. In addition to the acid-catalyzed rearrangement reaction, FeZn-DMC exhibits catalytic hydrogenation capability via heterolytic cleavage of the H–H bond over Zn–N frustrated Lewis pairs, and a CPE yield of 61.5% is obtained. The DFT simulation indicates that the acid sites and catalytic acid sites are ascribed to the tri-coordinatively unsaturated Zn2+ site (Zn(N)3) on the catalyst surface. Moreover, the DMC catalyst shows excellent stability and recycling performance. This work not only provides an efficient and green catalytic system for CPE and HCP preparation but also demonstrates the interesting bifunctional catalysis of both acid and hydrogenation catalysis over DMC. [ABSTRACT FROM AUTHOR]

The photoinduced conversion of biomass-derived chemicals to high value chemicals and advanced fuels is of great significance but still challenging. Herein, a green and efficient self-sensitized [2 + 2] cycloaddition process is developed to convert biomass-derived β-pinene and isophorone to spirocyclic molecules, which cannot be achieved by thermal catalytic conversion. The photoreaction can take place with isophorone as the self-sensitizer, with high selectivity and a yield of up to 91.1%. A triplet sensitization mechanism is disclosed by a combination of triplet quenching, phosphorescence quenching, Stern–Volmer kinetic analysis, DFT calculations and photochemical kinetic studies. When combined with hydrodeoxygenation, spiro-fuel is obtained with an overall yield of 85.0% showing a high density of 0.911 g mL−1 which is 16.8% higher than that of conventional aviation kerosene (ca. 0.78 g mL−1), along with excellent cryogenic properties. Notably the self-sensitized cycloaddition strategy can be extended to a wide range of biomass derived α,β-unsaturated ketones and alkenes. Thus, this work provides a promising ring-increasing route to upgrade low-density bio-derived feedstocks to high-density hydrocarbons. [ABSTRACT FROM AUTHOR]

Intrinsic activity and electrical conductivity play key roles in the hydrogen evolution reaction (HER). We herein design and synthesise nanocomposites of metallic cobalt and molybdenum nitride on a nitrogen-doped carbon matrix (Co–Mo2N@NC). The electrocatalyst exhibits extraordinary HER performance with an overpotential of only 47 mV at a current density of 10 mA cm−2 and Tafel slope of 43 mV dec−1 in a 1 M KOH solution, which is comparable to that of commercial 20 wt% Pt/C (43 mV at 10 mA cm−2). At high current density it even exhibits better performance than Pt/C (170 mV vs. 220 mV at 100 mA cm−2). The excellent activity stems from the roles of Co nanoparticles in improving electrical conductivity, optimizing the electronic structure and thus speeding up hydrogen desorption from Mo2N, and of the in situ formed Co(OH)2 in boosting water dissociation. Therefore, this work provides a low-cost potential electrocatalyst to replace Pt/C. [ABSTRACT FROM AUTHOR]

An oxidation-mediated defect and porosity enrichment strategy is developed for the synthesis of a new electrocatalyst consisting of cobalt (oxy)hydroxide nanosheet arrays (denoted as CoOxHy NSAs) grown on carbon cloth (CC), which feature a 3D hierarchical nanostructure with exceptional porosity and rich defects. The CoOxHy/CC shows exceptional activity and stability for the oxygen evolution reaction under neutral conditions, as indicated by its high current density of 38 mA cm−2 at 1.8 V, small Tafel slope of 121 mV dec−1, low overpotential of 430 mV, and 24 h durability at 10 mA cm−2 in 0.1 M phosphate buffer solution (PBS). [ABSTRACT FROM AUTHOR]

Defect engineering through grain boundaries, disordered regions, and atomic vacancies has the potential to achieve novel physical and chemical properties by modulating the atomic arrangements and electronic configurations. In particular, grain boundaries facilitates superior synergistic effects of different crystals. This work proposes an ingenious binder strategy to introduce grain boundaries in metal/semiconductor (M/MOx, M = Co, Ni) architectures via the thermal calcination of layered Co/Ni glycerolates bonded by melamine. XAFS and HRTEM results illustrate the abundant grain boundaries and disordered regions among the different crystals. DFT calculations demonstrate that the metal/semiconductor composite has metallic electrical conductivity with fast electron mobility, and the deformation of the electronic structure at the interface produces abundant reactive sites to improve the intrinsic activity. Therefore, this architecture (CoNim) shows excellent properties for electrocatalytic OER and ORR with a potential gap of 0.72 V at 10 mA cm−2, good stability (＞13 h for OER and ＞29 h for ORR) and perfect selectivity (electron transfer number, N = 4.0). As an air electrode for Zn–air batteries, it shows a long discharge time (23 h) and a peak power density of 81.7 mW cm−2. The facile binder strategy provides a new defect manufacturing method for the development of highly efficient bifunctional nanomaterials to be applied in energy devices. [ABSTRACT FROM AUTHOR]

It is of significant importance to capture and separate organic pollutants from water sources to combat the growing environmental problems. Advanced sorbent materials with rapid, high-capacity and selective sorption performances are desirable. Herein, a coordination framework (LIFM-WZ-4) containing micro-channels with a large percentage (70%) of “naked” nitrogens is reported, affording donor–acceptor (D–A) interaction abilities with specific selectivity for electron-deficient CO2 gases or cationic dyes. Especially, although with a neutral network, exclusively selective, fast and large adsorption capacities for cationic dyes from aqueous solutions were achieved, with a record high value of 1492.0 mg g−1 for MB+ among the materials reported to date. The underlying adsorption mechanism was probed from both kinetic and thermodynamic considerations, revealing a pseudo-second-order kinetic model and a D–A inducing chemisorption process accounting for the unique selectivity. The saturated sorbent can then be readily recovered by dye release in CH3CN. This easy recyclability provides potential for practical applications in water sanitation and dye separation. [ABSTRACT FROM AUTHOR]

Despite great progress, the development of anode materials with excellent properties for high-performance lithium-ion batteries (LIBs) remains challenging. Rational design and synthesis of novel hybrid nanomaterials that synergistically integrate the structural/compositional advantages of their components provides exciting opportunities and solutions. Here, we demonstrate a dilute atmosphere pyrolysis strategy for the one-step synthesis of a new hybrid nanomaterial, CoO/C yolk–shell nanostructures (CoO/C YSNSs), from a Co-containing metal–organic framework precursor, ZIF-67. The CoO/C YSNSs integrate CoO and carbon into a unique hierarchical and quasi-homostructural architecture, in which both the yolk and shell comprise ultrafine CoO nanoparticles homogeneously embedded in highly porous, conductive and N-doped carbon. Benefiting from such structural and compositional features, CoO/C YSNSs deliver ultrahigh and stable lithium storage performances (retained capacity up to 1970 and 680 mA h g−1 even after 1000 charge/discharge cycles at a current density of 100 and 1000 mA g−1, respectively), and rank among the best cobalt oxide-based anode materials. The formation of CoO/C YSNSs is also investigated and attributed to two synergistic processes of dynamic redox competition and heterogeneous contraction. Our work provides new stimuli to the development of complex hybrid nanostructure-based advanced electrode materials for high-performance batteries. [ABSTRACT FROM AUTHOR]

Through dynamic spacer installation, five fluorescent metal–organic frameworks (MOFs) have been constructed based on a proto-MOF LIFM-28 and multivariate ligands as fluorophores. The emissions are tunable via insertion of fluorescent ligands, demonstrating a versatile approach for luminescence tuning by virtue of dynamic spacer installation using swing-role MOFs. [ABSTRACT FROM AUTHOR]

2D graphitic carbon nitride (g-C3N4) has attracted great attention as one of the rising-star candidates for prominent water-splitting photocatalysts. Here, we report an extremely facile one-step, template-free method to synthesize ultrathin g-C3N4 nanosheets (CN-UMF) by thermal polycondensation of urea simply covered with kitchen-available melamine foam (MF). Compared with g-C3N4 agglomerates (CN-U) prepared without the covering of MF, the as-synthesized CN-UMF has an average thickness of about 4.5 nm and an enlarged surface area of 150.3 m2 g−1, leading to enhanced visible light absorption and charge carrier separation abilities. Therefore, it is able to serve as an efficient water-splitting photocatalyst to result in an outstanding hydrogen production rate of 5498 μmol g−1 h−1. This work provides a new facile strategy for the scalable synthesis of 2D g-C3N4 photocatalysts and paves the way for batch and green production of other 2D materials with good performance. [ABSTRACT FROM AUTHOR]

A metalloporphyrin Cu5-cluster based MOF (metal–organic framework), [Cu4.5((H4TZPP)(TZPP)Cl2)(H2O)0.5]·CH3NH2CH3·7EtOH·8H2O (LIFM-WZ-3) was synthesized from the tetrapodal ligand 5,10,15,20-tetrakis[4-(2,3,4,5-tetrazolyl)phenyl]porphyrin (H6TZPP) and copper chloride. LIFM-WZ-3 exhibits a rare 2D + 3D → 3D interpenetration topology, of which the frl-type 3D MOF and a layered 2D HOF (hydrogen bond organic framework) are intertwined, leading to an anionic framework with 1D spindle-like channels. Powder X-ray diffraction analysis reveals that the framework is stable in acid, base and various organic solvent environments. LIFM-WZ-3 exhibits moderately high separation performances for CO2/CH4, CO2/N2, C3H6/CH4, C2H6/CH4, and C2H4/CH4 at room temperature. Specifically, the anionic framework in LIFM-WZ-3 containing dimethylamine cations can selectively adsorb cationic organic dyes from aqueous pollutants for recycle purpose. The high adsorption capacity for methylene-blue (MB+, 983 mg g−1) and crystal violet (CV+, 713.5 mg g−1) ranks the highest among those MOFs ever reported. [ABSTRACT FROM AUTHOR]

Mitochondria targeted phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has excelled as an effective approach among other non-specific techniques for its high selectivity, non-invasiveness and low systemic toxicity. Derivatives of porphyrins, indocyanine dyes and rhodamine are widely utilized for cancer PDT or PTT. However, limitations, such as hypoxia and heat resistance of PDT and PTT, have restricted their efficacy in tumor treatment, making it urgent to develop highly efficient theranostic agents with synergistic effects. Aza-boron-dipyrromethene (aza-BODIPY) has shown promising prospects for synergistic phototherapy due to its outstanding reactive oxygen species (ROS) generation and photothermal effect. Herein, we designed and synthesized a near-infrared (NIR) aza-BODIPY derivative MeOABBr (ΦΔ = 84%). By encapsulating it with polyethylene glycol–folic acid (PEG–FA) and polyethylene glycol–triphenylphosphonium (PEG–TPP), tumor and mitochondria dual targeting nanoparticles (FMAB NPs) have been obtained. Triggered by NIR irradiation, FMAB NPs could generate ROS and hyperthermia (η = 40%) to cause mitochondrial dysfunction, resulting in cell apoptosis. Simultaneously, FMAB NPs, with unique optical properties, can be monitored precisely by photoacoustic, fluorescence and photothermal imaging in vivo. In particular, as proved by both in vitro and in vivo experiments, tumor-mitochondria dual targeted FMAB NPs exhibit high phototherapeutic efficacy without toxicity to normal tissues. [ABSTRACT FROM AUTHOR]

Hydrophilic zwitterionic guest encapsulation by metallo-supramolecular cages through synergetic coordination, H-bonding and hydrophobic interactions. [ABSTRACT FROM AUTHOR]

Through stepwise post-synthetic spacer insertion and click reactions, six Zr-MOFs with different types and amounts of functional groups have been constructed based on proto-MOF PCN-700. Their gas adsorption capacities and selectivities have been greatly improved and finely tuned, demonstrating the combinatorial effect of pore surface modification and pore space partition. [ABSTRACT FROM AUTHOR]

Well-dispersed and highly efficient molybdenum nitrides on a nitrogen-doped carbon matrix (Mo2N@NC) are reported as a new and active electrocatalyst for hydrogen evolution in alkaline electrolyte. The key point in fabricating this catalyst is using HNO3-treated melamine, other than pristine melamine, as carbon and nitrogen pools to realize the complete nitridation of MoO3 to Mo2N nanoparticles of 4 nm size and at the same time to generate a nitrogen-doped carbon matrix to support these nanoparticles by thermolysis under an Ar atmosphere. The as-prepared Mo2N@NC exhibits excellent HER activity in 1 M KOH with a pretty low overpotential of 85 mV to achieve a current density of 10 mA cm−2 and a small Tafel slope of 54 mV dec−1, which is among the best for Mo-based compounds and better than those of most non-noble metal electrocatalysts to date in alkaline media. It is also much better than those of the incomplete nitride compounds (MoO2/Mo2N@NC) and the mixture of nitrides and carbides (Mo2N/Mo2C@NC) fabricated under similar conditions, from aspects of overpotential, Tafel slope, exchange current density, conductivity, active surface area and turnover frequencies. Therefore, Mo2N represents a new kind of very active HER catalyst in alkaline electrolyte. Also, this work provides an effective method to fabricate metal nitrides/carbon composites for other applications. [ABSTRACT FROM AUTHOR]

The structure of the perovskite solar cells (PSCs) is either mesoporous or planar. Here, a novel structure for highly efficient and stable PSCs is proposed, i.e., an embedded structure, which combines the advantages of the mesoporous and planar structures. The embedded structure utilizes a TiO2 nanoparticle embedded perovskite (CH3NH3PbI3) film as the absorption layer. The presence of TiO2 nanoparticles in the perovskite film could improve the electron extraction, and promote the formation of a compact perovskite layer with large grains. Consequently, the performance of the PSCs is significantly improved with the efficiency increasing from 16.6% for the planar structure to 19.2% for the embedded structure, which is the best performance of the MAPbI3-based PSCs. Furthermore, the TiO2 embedded perovskite films present better long-term stability than the pristine perovskite films, and the corresponding PSCs, which have no other chemical modifications, also show excellent stability with efficiency approaching 80% (for average) or 90% (for the best) after being exposed to air for 28 days without encapsulation. [ABSTRACT FROM AUTHOR]

A UiO-66-MOF-based membrane UiO-66-TEM (1) was prepared by the assembly of methacrylamide-decorated UiO-66-NH-Met with a thiol side chain-attached polysiloxane (PSI-SH) via a photoinduced thiol–ene click reaction. The obtained membrane 1 can be a platform to support Au nanoparticles (Au NPs) to generate an Au–MOF–polymer composite membrane Au@UiO-66-TEM (2). 1 and 2 can be used to build highly efficient continuous flow-through membrane reactors for Knoevenagel condensation of 4-nitrobenzaldehyde with malononitrile and 4-nitrophenol (4-NP) reduction at ambient temperature, respectively. [ABSTRACT FROM AUTHOR]

A novel Pd(ii)–Pb(ii) bimetallic metal–organic framework Pd(ii)–Pb(ii)–MOF (B) which contains an N-heterocyclic tetracarbene Pd(ii) moiety was synthesized based on a chelating N-heterocyclic dicarbene Pd(ii)–NHDC ligand (A) under solvothermal conditions. It can be a highly active heterogeneous catalyst for three-component cyclotrimerization via benzyne species. [ABSTRACT FROM AUTHOR]

The development of low cost and durable electrocatalysts for the oxygen evolution reaction (OER) for water splitting remains a great challenge. Here, we developed strongly coupled hybrid nanowires (NWs) of anion (Cl− and CO−) doped cobalt hydroxide coated with nanosheets of graphitic carbon nitride (Co(OH)2@g-C3N4) through an in situ hydrothermal method. With 5% g-C3N4 added in the synthesis, we obtained perfectly coated Co(OH)2 by g-C3N4 nanosheets with an overall diameter of ∼110 nm and a coating layer of ∼10 nm. The structural and compositional analyses confirm the strong interaction between g-C3N4 and Co(OH)2 that makes the hybrid highly effective for the OER. As a result Co(OH)2@g-C3N4 NWs exhibit an excellent over-potential of 0.32 V at 10 mA cm−2 as well as extraordinary stability, which are better than those of the state-of-the-art noble metals (IrO2 and RuO2) and most reported Co- and C3N4-based electrocatalysts although both Co(OH)2 and g-C3N4 separately display very fair performance. Furthermore, a combination of Co(OH)2@g-C3N4 and Pt/C delivers a current density of 80 mA cm−2 at 1.9 V for overall water splitting. [ABSTRACT FROM AUTHOR]

Fully structural interconversions between monomeric Pd2L4 and interlocked dimeric Pd4L8 cages have been investigated to elucidate their thermodynamic stability defined by their anion-guest binding behaviours. [ABSTRACT FROM AUTHOR]

The trap states and the intrinsic nature of polycrystalline organometallic perovskites cause carrier losses in perovskite solar cells (PSCs) through carrier recombination at the surface and subsurface of the perovskites, leading to lowered conversion efficiency. Herein, to reduce the carrier losses, an intelligent approach concerning surface passivation and interfacial doping of the perovskite is proposed by introducing an F4TCNQ interfacial layer. The trap states at the perovskite surface are efficiently suppressed, leading to a homogenous surface potential of perovskite, which avoids the surface carrier recombination. The Fermi level of the perovskite is shifted to its valence band by 0.2 eV, inducing an energy barrier for electron diffusion and contributing directly to a minimized carrier recombination at the subsurface of the perovskite film. Consequently, the performance of the PSCs is remarkably improved, with the average efficiency increased from 14.3 ± 0.9% to 16.4 ± 1.0% (with a maximum efficiency of 18.1%). Moreover, the PSCs with the dual function interfacial layer show enhanced long-term stability in ambient air without device encapsulation. [ABSTRACT FROM AUTHOR]

Lead halide perovskite solar cells (PSCs) suffer from poor long-term stability, especially due to photo-induced degradation, as PSCs function under continuous sunlight. However, the origins of this instability have not been clearly explored. Herein, the photo-induced degradation of PSCs with mesoporous and planar architectures are investigated, respectively, and the main origin is proved to be correlated with the hole transport material (HTM)/metal (Au) electrode interface. The solar irradiation of PSCs causes significant deterioration of device performance, with the efficiency decreasing from approximately 18% to 2.46% for planar PSCs in 180 min. Electrical analysis of the PSCs and XPS measurements show that the deteriorated performance is induced by retarded carrier extraction from the HTM to the Au electrode, due to a broken interface binding. Accordingly, in situ renewal of the Au electrode was found to cause notable recovery (approximately 80%) of the device performance of both mesoporous and planar PSCs. In comparison, the material degradation of perovskite and the TiO2/perovskite interface were also studied; however, these showed minor effects on the photo-induced degradation of PSCs. These results indicate that the photo-induced degradation of PSCs is mainly caused by the HTM/Au interface. This study provides an important insight into the photo-induced degradation of PSCs, and is crucial for the fabrication of highly photo-stable PSCs. [ABSTRACT FROM AUTHOR]