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Diketopyrrolopyrrole (DPP)-based donor–acceptor (D–A) polymers have been extensively employed in a variety of organic electronic devices. However, systematically increasing the quantity of DPP acceptor blocks in the repeating unit and its impact on the performance of organic thin-film transistors (OTFTs) have not been investigated yet. Herein, an acceptor-quantity modulation strategy is put forward to further optimize the optoelectronic properties and the OTFT performance of DPP-based D–A polymers. Thus, three polymers that are composed of 1–3 DPP acceptor blocks are synthesized via C–H direct arylation polymerization (DArP). Notably, these polymers can be obtained within 0.5 h under the optimal DArP conditions and they demonstrate a decent number average molecular weight of 13–25 kg mol−1. Among the three polymers, the dual-acceptor polymer P1DPP-BT exhibits typical ambipolar OTFT performances with electron mobility (μe)/hole mobility (μh) of 0.7/0.45 cm2 V−1 s−1, respectively. Further success in enhancing μe is achieved in the triple-acceptor polymer P2DPP-BT with one more DPP block in the backbone. It shows the best μe up to 1.1 cm2 V−1 s−1. Unexpectedly, incorporating the third DPP block into the repeating unit leads to a dramatic performance decrease (μe/μh ∼ 10−2 cm2 V−1 s−1). Further characterization studies indicate that the lowest unoccupied molecular orbital (LUMO) energy levels decrease monotonically as the acceptor quantity increases. Meanwhile, the polymer packing texture changes from an edge-on orientation to a face-on orientation with a dramatically decreased crystallinity. Thus, the triple-acceptor polymer maintains a balance between the energy levels, crystallinity and packing textures, resulting in the highest electron mobilities among the three polymers. [ABSTRACT FROM AUTHOR]

Sidechain engineering is a powerful molecular design strategy to tune the solid-state packing and structural ordering of conjugated polymers. While the modification of the type and length of sidechains has become a key strategy in tuning the polymer properties, the effects of the sidechain direction on the optoelectronic properties of polymers have been less investigated. Herein, two new isomeric diketopyrrolopyrrole (DPP)-based conjugated polymers (namely P3BT-in and P3BT-out) with different sidechain substitution directions are designed and synthesized based on the O-alkylated DPP isomer (pyrrolo[3,4-c]pyrrol-1(2H)-one). Through comprehensive theoretical studies and experimental characterization, the effects of the sidechain-substitution direction on the optoelectronic properties of polymers and the corresponding performance of organic transistors and near-infrared organic phototransistors (NIR-OPTs) were systematically investigated. Compared to P3BT-out with sidechains spreading in the outer way, P3BT-in with sidechains in the inner way has better molecular planarity, resulting in increased crystallinity. In addition, P3BT-in has deeper LUMO energy levels and a narrower bandgap of 1.06 eV with a stronger light absorption ability, leading to increased electron mobility and n-type NIR photosensitivity. Overall, tuning the sidechain substitution direction could be a useful strategy for the rational design of functional polymers. [ABSTRACT FROM AUTHOR]

Two perylenediimide (PDI) regioisomers with the central core substituted at the ortho (Y-αPDI) and bay (Y-βPDI) areas of the PDIs were successfully prepared. The regioisomeric effects on the physicochemical and charge-transport properties were thoroughly investigated. The results unravel that Y-βPDI shows ambipolar transport with higher mobilities compared to its α-counterpart, which is due to its favourable molecular geometry, stronger intermolecular interaction and improved electron-withdrawing ability. [ABSTRACT FROM AUTHOR]

Donor engineering plays an important role in tuning the intramolecular charge transfer (ICT) interactions of donor–acceptor (D–A) molecules and the related performance in the further applications. In comparison to the complicated and time-consuming molecular skeleton exploitation, optimization of the donor number and the substitution position is more facile and efficient. Herein, different quantities of diphenylamine (DPA) units are incorporated into the tris(2,4,6-trichlorophenyl)methyl (TTM) radicals from various directions. The effects of the donor number and the substitution position on the ICT interactions and the photothermal conversion performance are investigated. It is found that TTM-DPA (644 nm), TTM-2DPA (650 nm), and TTM-3DPA (637 nm) with various DPA units attached on different arms of the TTM core exhibit similar absorption maxima and high photoluminescence (PL) quantum yields (over 56%) in cyclohexane solutions. However, when multi-DPA units are introduced on the unilateral arm of the TTM unit, the absorption maximum red shifts to 675 nm for TTM-BDPA and 717 nm for TTM-TDPA. Meanwhile, no obvious PL can be detected using a spectrometer. The near-infrared (NIR) absorbance and the nonradiative transition of the TTM radicals contribute to their photothermal conversion. Consequently, remarkable photothermal conversion efficiencies of 41% and 50% are achieved for TTM-BDPA and TTM-TDPA, respectively. Our study provides an alternative design rule for controlling the ICT effect and shows that organic radicals have potential for application in photothermal therapy in the near future. [ABSTRACT FROM AUTHOR]

Stretchable electronics have received intense attention due to their broad application prospects in many areas, and can withstand large deformations and form close contact with curved surfaces. Stretchable conductors are vital components of stretchable electronic devices used in wearables, soft robots, and human–machine interactions. Recent advances in stretchable conductors have motivated basic scientific and technological research efforts. Here, we outline and analyse the development of stretchable conductors in transistors and circuits, and examine advances in materials, device engineering, and preparation technologies. We divide the existing approaches to constructing stretchable transistors with stretchable conductors into the following two types: geometric engineering and intrinsic stretchability engineering. Finally, we consider the challenges and outlook in this field for delivering stretchable electronics. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) regulated by heteroatoms have displayed great potential as electrocatalysts for highly efficient hydrogen evolution reaction (HER); however, the controllable synthesis of an axial coordination structure of SACs to achieve robust HER performance remains a great challenge. Herein, we have proposed a doping-adsorption-pyrolysis strategy to construct NiN4–Cl active sites with axial Cl coordination for accelerating electrocatalytic HER. The obtained NiN4–Cl SAs/NC catalyst exhibits superior HER activity with low over-potential, small Tafel slope, high turnover frequency, and long-term stability. Density functional theory calculation reveals that the excellent HER performance of NiN4–Cl SAs/NC originates from the axial Cl-coordination-induced electronic localization enhancement, which is beneficial for the adsorption and activation of H* intermediate, thus accelerating the HER process. This work opens a new opportunity for rational design and construction of high-performance SAC catalysts by axial coordination strategy for electrocatalytic application. [ABSTRACT FROM AUTHOR]

The safety of animal-origin foods has a major influence on human health. Although the use of veterinary drug additives (VDAs) significantly promotes the normal growth and development of animals against diseases, the excessive consumption of VDAs is always the most worrying part. Thus, realizing a direct and prompt detection of solid VDAs is highly desirable. In this study, we incorporated a functional unit of triazolo [4,5-c] pyridine (TP) in polymer semiconductors. The theoretical simulation demonstrates that TP can effectively form hydrogen bonding with the VDA molecules. Furthermore, highly sensitive polymeric field-effect transistors (PFETs) are fabricated through the configurational design of low-dimensional polymer networks (LDPNs). The conducting channel and hydrogen bonding sites of the LDPN-based PFETs could be directly exposed to the analytes, thereby effectively capturing VDA molecules and converting the stimuli into electrical signals. The obtained PFET-based solid sensors showed highly sensitive and stable detection of melamine powders at a low operation voltage of −5 V. The detection limit realized is lower than the international standards in animal feeds (2.5 ppm). These results demonstrate the promising applications of PFETs for high-efficiency and low-power-consumption sensors for solid detection or biological diagnosis. [ABSTRACT FROM AUTHOR]

Determining the effect of crystal facets on reaction performance is essential for designing an efficient propane oxidation catalyst. Herein, α-MnO2 nanowires with exposed (110), (211), (310) and (200) facets were proposed, and their crystal facet-dependent reactivity to propane oxidation was investigated. The resultant α-MnO2 nanowires with predominantly exposed (110) facets showed the maximum propane oxidation activity (T90 = 262.1 °C), oxidation rate, and turnover frequency (at 230 °C), and high stability during the oxidation of propane. In situ diffuse reflectance infrared Fourier transform spectroscopy revealed that the oxidation to form carboxylates is the decisive step; therefore, the production of reactive oxygen species is very important. The results from density of states computations revealed that the lowest electron energy was present in the (110) facet, which helps in the generation of reactive oxygen species and the regulation of the surface valence of Mn. The characterization and calculation results indicated that the (110) facets are conducive to forming oxygen vacancies, which allowed the activation and adsorption of O2 and propane, resulting in significantly enhanced propane oxidation activity. Apart from offering new insights about the structure–activity relationship of α-MnO2 with different facets exposed for short-chain volatile oxidation reactions, this study proposes a technique that can be used for improving other manganese-based catalyst oxidation systems. [ABSTRACT FROM AUTHOR]

Polymer semiconductors with coplanar, π-extended confirmation and high electron affinity are regarded as the promising candidates for high-mobility ambipolar organic field-effect transistors. Herein a highly electron-deficient, coplanar, π-extended bis-pyridal[2,1,3]thiadiazole (BPT) acceptor is embedded into two novel D–A type conjugated polymers (PBPT-TT and PBPT-FTT), in which alkyl-substituted terthiophenes (TT) and alkyl-substituted difluoroterthiophenes (FTT) are used as the donor segments, respectively. Moreover, a facile fluorination strategy is adopted to regulate the backbone coplanarity, optoelectrical properties, and film organization coupled with the charge transport properties of polymers. It is found that, compared with PBPT-TT, the attachment of electron-deficient fluorine substituents to the main chain of PBPT-FTT achieves not only improved electron affinity, but also enhanced backbone coplanarity owing to the formation of the F⋯S noncovalent conformation lock. Such good backbone coplanarity and fluorine substituents endow PBPT-FTT with improved interchain organization ability, thereby achieving a more uniform lamellar structure and a smaller π–π stacking distance than those of PBPT-TT. Benefiting from these merits, PBPT-FTT based organic field-effect transistors exhibit significantly improved ambipolar transport performance relative to PBPT-TT. The highest hole (μh) and electron (μe) mobilities of PBPT-FTT are determined to be 0.332 and 1.602 cm2 V−1 s−1, respectively; both of them are much higher than those of PBPT-TT (μh/μe = 0.0135/0.0191 cm2 V−1 s−1). Our findings suggest that the introduction of accessible fluorine substituents in the polymer main chain is a feasible and effective pathway to enhance the backbone coplanarity, film organization, and charge transport ability. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskites exhibit superior optoelectrical properties and have been widely used in photodetectors. Perovskite photodetectors with excellent detectivity have great potential for developing artificial photonic synapses which can merge data transmission and storage. They are highly desired for next generation neuromorphic computing. The recent progress of perovskite photodetectors and their application in artificial photonic synapses are summarized in this review. Firstly, the key performance parameters of photodetectors are briefly introduced. Secondly, the recent research progress of photodetectors including photoconductors, photodiodes, and phototransistors is summarized. Finally, the applications of perovskite photodetectors in artificial photonic synapses in recent years are highlighted. All these demonstrate the great potential of perovskite photonic synapses for the development of artificial intelligence. [ABSTRACT FROM AUTHOR]

The increasing use of pesticides has raised concerns about the risks of exposure to pesticides. Rapid, simple and sensitive detection of pesticides is still a challenge in the current analytical technology. Herein, a perfluorinated copper phthalocyanine (F16CuPc) organic field-effect transistor (OFET) modified by β-cyclodextrin (β-CD) was used to detect boscalid molecules in solution. As a molecular carrier, β-CD will capture boscalid to form an inclusion complex. The hydroxyl group in β-CD and the carbonyl group in boscalid form a dipole–dipole interaction with F16CuPc, which induces more carriers in the device channel, which finally manifests as a significant increase in the maximum current of the device. When using β-CD as the modification layer, the detection limit of the device can be as low as 2.40 × 10−11 g L−1, which is 5 orders of magnitude lower than the internationally permitted MRL value. [ABSTRACT FROM AUTHOR]

A series of novel bis-acenaphthoquinone diimides featuring a highly electron-deficient bis-acenaphthoquinone core are facilely synthesized via Knoevenagel condensation reaction. The diimides show high electron deficiency and good coplanar conformation, together with one of them having a maximum electron mobility up to 0.038 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

Direct and sensitive short-wavelength ultraviolet (UVC) dosimeters could provide a safer disinfection environment against viruses. We developed direct, quantitative, specific and highly sensitive UVC dosimeters based on DNA nanostructure-modified graphene field-effect transistors. Detectable doses of the dosimeters range from 0.005 to 6 kJ m−2 and such dosimeters have at least 5 times better sensitivity than the current direct UV dosimeters. [ABSTRACT FROM AUTHOR]

Developing efficient and durable electrocatalysts with uniform sizes for the hydrogen evolution reaction (HER) in the entire pH range and seawater is critical for scalable and sustainable hydrogen production. Herein, we report a supramolecular starch-assisted confinement–assembly–pyrolysis (SCAP) strategy for the synthesis of ultrasmall Rh2P nanoparticles with high dispersion and low loading anchored on N,P-doped porous carbon (NPC). The Rh2P/NPC composite exhibits an unprecedented HER activity with small overpotentials at 10 mA cm−2 (40 mV in 0.5 M H2SO4 and 17 mV in 1 M KOH), as well as superior stability in both acidic and alkaline media. In addition, the Rh2P/NPC catalyst also exhibits an excellent HER performance in the entire pH range. Especially, the Rh2P/NPC catalyst shows an electrocatalytic HER activity superior to that of a 20% Pt/C catalyst in natural seawater, especially under large current densities. It only needs 160, 341 and 411 mV versus RHE to achieve current densities of 10, 100, and 300 mA cm−2, respectively. To the best of our knowledge, this Rh2P/NPC material is the best electrocatalyst reported thus far for seawater electrolysis. Moreover, the Rh2P/NPC catalyst also shows good stability over a wide range of current densities. All these results indicate that the Rh2P/NPC catalyst can be used as a robust catalyst for hydrogen production via direct seawater electrolysis. In situ X-ray absorption spectra revealed the strong interaction between the Rh–P site and H2O during the HER catalytic process in 1 M KOH, revealing the positive role of the Rh–P site in the HER. Theoretical calculations demonstrate that the strong synergistic effects between Rh2P nanoparticles and NPC modify the electronic structure to accelerate the HER kinetics. More interestingly, the SCAP strategy not only yields a robust and pH-universal HER catalyst, but also enables a general, green, and gram-scale synthesis of other metal phosphides. [ABSTRACT FROM AUTHOR]

Quinoidal bithiophene (QBT) is a highly attractive building block for high-performance polymeric semiconductors. However, it is a challenge to prepare a single regioisomer of a QBT-based building block using an indophenine reaction. Here, we introduce steric hindrance of the methoxyl group in a QBT-based system, which ensures the stereospecificity of the resulting monomers. Both methoxylated QBT (MQBT) and fluorinated MQBT (2FMQBT) monomers are copolymerized with 2,2′-bithiophene and 3,3′-difluoro-(2,2′-bithiophene) (DFBT) to form four donor–acceptor (D–A) copolymers, which display a narrow optical bandgap (<1.20 eV). Because of the introduction of fluorine atoms, P2FMQBT-DFBT displays good coplanarity and close solid-state packing, possessing the highest hole mobility of up to 2.70 cm2 V−1 s−1, which represents one of the best values for quinoidal polymers. Most importantly, the preparation of single regioisomers of MQBT and 2FMQBT is synthetically feasible for creating new QBT-based high-performance polymers. [ABSTRACT FROM AUTHOR]

As one of the basic units of optoelectronic devices, organic field-effect transistors (OFETs) are not only promising candidates for understanding the intrinsic charge transport mechanism of organic semiconductors (OSCs), but are also attractive for various applications, such as active-matrix displays, logic circuits, photodetectors, sensors and so on. Shrinking the active layer thickness in OFETs to a few molecular layers (MLs) or even down to a monolayer is a very attractive strategy in many aspects: (1) minimize material consumption while maintaining equal or even better charge transport properties, (2) reduce bulk injection resistance for the possible realization of Ohmic contact and short channel devices, (3) enhance phototransistor performance, (4) improve sensing performance, etc. In this review, we first comprehensively summarized the effect of active layer thickness on OFET performances in thin-film and single crystal devices in terms of mobility (μ) and contact resistance (Rc). Then the phototdetector and sensor applications of OFETs toward ultrathin two-dimensional (2D) molecular materials at the monolayer limit are discussed with emphasis on the high performance of monolayer molecular crystal (MMC) based devices. Finally, the challenges and perspectives regarding the controllable preparation of MMCs and corresponding devices applications are discussed. [ABSTRACT FROM AUTHOR]

A heterocycloarene derivative (S-Octulene) possessing two sulfur atoms was conveniently synthesized through Bi(OTf)3-catalyzed cyclization from a macrocyclic tetramethoxyethenylated precursor. The physical properties of S-Octulene and its supramolecular host–guest interaction with C60 and C70 were investigated by fluorescence titration and 1H NMR. The solution-processed organic field-effect transistor (OFET) measurements demonstrated that S-Octulene behaved as a p-type semiconductor with a hole mobility exceeding 0.01 cm2 V−1 s−1. Our findings pave a new path to design novel heterocycloarenes for the development of host–guest chemistry and organic semiconductors. [ABSTRACT FROM AUTHOR]

Rational design of alternative, cost-effective and highly active electrocatalysts for the hydrogen evolution reaction (HER) in alkaline and neutral media is greatly desirable and challenging. In this work, we developed a simple but effective manganese-metal-heteroatom doping strategy to realize the simultaneous modulations of the active site number, water dissociation, and hydrogen adsorption free energy in pyrite NiS2 hierarchical nanosheets to significantly boost alkaline and neutral HER catalysis. Specifically, the incorporation of Mn heteroatoms into the NiS2 system, as revealed by HRTEM, XPS, XANES spectra and theoretical studies, not only induce lattice distortions and defects for increasing the exposure of active sites, but also effectively optimize the electronic structure configuration of Ni sites, leading to optimal hydrogen adsorption free energy. In addition, the doped Mn heteroatom itself can act as a water-activated site to lower the energy barrier of water dissociation. As a result, the synergistic regulation of active sites and HER kinetics brings nearly 9-fold enhancement of alkaline HER activity for Mn-doped NiS2/Ni foam (NF) with a quite low overpotential of 71 mV to reach 10 mA cm−2 in 1 M KOH, which is among the most active HER electrocatalysts reported to date. Despite few reports about the effective neutral HER on transition-metal sulfides so far, a small overpotential of 84 mV at 10 mA cm−2 can be achieved in 1 M phosphate-buffered saline (PBS, pH 7). Furthermore, the Mn-doped NiS2/NF electrode also exhibits efficient and stable HER performances in near-neutral real seawater and has no obvious catalytic degradation after various extreme bending tests, verifying its high flexibility and robustness under severe conditions, which vastly broadens its application prospects. [ABSTRACT FROM AUTHOR]

Solution-processed polythiophene thin films suffer from low efficient inter-molecular carrier hopping and undermined conjugation arising from chain twist and random entanglement. Forming a graphene like two-dimensional (2D) cross-linked conjugated polymer network is one of the promising strategies to solve this problem. Here, we synthesize a decimeter-sized 2D cross-linked polythiophene network (2DPT) via surface-confined Ullmann coupling, with a thickness of 1.3 nm and a transmittance of ∼97% at 550 nm. The 2D cross-linked network improves charge carrier transport, resulting in a carrier mobility up to 4.6 cm2 V−1 s−1 and conductance of 206 S cm−1, much higher than that of normal solution-processed conjugated polymer films. Owing to the efficient carrier transport, atomic thickness and large conjugated surface, this new conjugated polymer exhibits a fast response to stimuli as the channel in a liquid-gated H2O2 sensor, and low contact resistance as bottom-contact electrodes in organic field-effect transistors with high carrier mobility. [ABSTRACT FROM AUTHOR]

Development of nonprecious, efficient, and stable electrocatalysts for overall water splitting under mild conditions is crucial but still a huge challenge for the renewable energy techniques. Herein, a facile hydrothermal and then selenization strategy is proposed to synthesize hierarchical nickel sulfoselenide (NiS2(1−x)Se2x) hollow/porous spheres with controllable composition for electrocatalytic water splitting in neutral media. By regulating the degree of selenization, the Se/S atomic ratio in the nickel sulfoselenides can be controlled to realize the tunable electronic structure of nickel to boost its intrinsic activity. Benefiting from their unique structural features and the anion doping effect, nickel sulfoselenides, especially with the chemical composition Ni(S0.5Se0.5)2, are discovered to exhibit high activity and stability toward both hydrogen and oxygen evolution reactions under neutral conditions. When using Ni(S0.5Se0.5)2 as a bifunctional electrode as both the anode and cathode in a neutral electrolyte, it demonstrates a durable activity for overall water splitting to drive 10 mA cm−2 at a cell voltage of merely 1.87 V, outperforming the noble metal-based Pt/C and IrO2 couple. This study not only offers a new type of promising earth-abundant electrocatalyst towards water electrolysis under benign conditions, but also highlights that anion doping engineering or composition control can be an elegant strategy to improve the electrochemical catalytic performance. [ABSTRACT FROM AUTHOR]

Described herein is the merging of allylic C(sp3)–H activation and directed C(sp2)–H activation into a single approach for discovering unprecedented chemical transformations. As a proof-of-concept, we disclose for the first time the rhodium-catalyzed regioselective oxidative annulation of anilines with allylbenzenes to deliver a variety of indoles. In this work, the C3 and C2 positions of the allylic segment are set to construct C–N and C–C bonds, respectively. [ABSTRACT FROM AUTHOR]

A novel bisthiophene-fused diketopyrrolopyrrole unit (4,11-bis(2-octyldodecyl)-7H,14H-thieno[3′,2′:7,8]indolizino[2,1-a]thieno[3,2-g]indolizine-7,14-dione, BTI) has been designed as an electron acceptor and used to copolymerize with thiophene and bithiophene as electron donors to construct two D–A conjugated polymers, P1 and P2via Stille coupling, respectively. The two polymers showed excellent thermal stability, broad light absorption and a narrow energy band gap. P1 and P2 were used to fabricate organic field-effect transistors (OFETs) to evaluate their charge transport characteristics. P2 showed much better hole transport performance with a mobility of 0.1 cm2 V−1 s−1. Near-infrared (NIR) phototransistors were also fabricated by using the two polymers blended with PC71BM as the active layer. With illumination of 35 μW cm−2 at a wavelength of 850 nm, the photocurrent/dark-current ratio (P) and photoresponsivity (R) of the phototransistor based on P1/PC71BM were 3.6 × 104 and 270 A W−1, respectively. For P2/PC71BM, P was 2.5 × 104 and R reached 2420 A W−1. [ABSTRACT FROM AUTHOR]

In this paper, a facile route is reported for the synthesis of MIL-53(Al) particles with different sizes and morphologies via the addition of various ratios of an esterified ligand to realize the deferred release of the ligand. Detailed proof indicates that the hydrolysis and deferred release of the ligand play a crucial role in modulating the morphology and size of the obtained MIL-53 nanoparticles without disrupting the original structure and framework of MIL-53. A possible mechanism for the growth of MIL-53 crystals with different exposed facets is proposed based on the structure of MIL-53 and BFDH (Bravais, Friedel, Donnay and Harker) theory. In addition, the influence of the crystal morphologies or exposed surfaces on the breathing effect and gas adsorption performance was evaluated using N2 and CO2 adsorption, and the as-prepared MIL-53 particles showed different adsorption isotherms and adsorption behavior under the same conditions. The MIL-53 particles synthesized using an appropriate amount of an esterified ligand could present an enhanced surface area when compared to that of bulk MIL-53, and the breathing effect during CO2 adsorption was moderate, while excessive amounts of the esterified ligand resulted in a decrease in the porosity and the formation of boehmite. Based on the experiment, the discrepancy in the breathing effect is mainly attributed to the stability of the narrow pore form with different exposed facets, but not the decreased particle size. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) nanomaterials have received significant attention for large-scale functional applications due to their large specific surface areas as well as desired electrical, physicochemical, and catalytic properties. Herein, we present a facile and effective synthetic route for in situ grown 3D hierarchical Ni3S2 superstructures (rod-like arrays and nanoforest patterns) on nickel foam. This handy strategy endows the Ni3S2 superstructures with large surface active areas, porosity, and macro-/mesoporous structures. We have shown that these materials can serve as highly active, binder-free, bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Moreover, these materials were found to provide a ∼100% faradaic yield towards both HER and OER and exhibit remarkable catalytic stability (for ＞50 h). [ABSTRACT FROM AUTHOR]

n-Channel organic light-emitting field-effect transistors (OLETs) based on perylene diimide (PDI-C13) with improved air stability were fabricated using a short channel length and thermal annealing. Both shortening of channel length and thermal annealing improved source–drain current; thermal annealing facilitated charge injection and improved PLQY of the PDI-C13 film. The light-emitting mechanism of OLETs was elaborated: that is, the OLETs were lateral organic light-emitting diodes in nature, the gate voltage (VGS) modulated light intensity by controlling electron density, and the light intensity was a quadratic function of VGS. This is the first example of n-channel OLETs that can operate in air. [ABSTRACT FROM AUTHOR]

A new molecule, 5,5′-bis(4,6-bis((E)-4-(octyloxy)styryl)pyrimidin-2-yl)-2,2′-bithiophene (OSPB), was designed and synthesized. It contains two D–π–A–π–D (donor–π–acceptor–π–donor) segments with an alkoxy group D and a pyrimidine moiety A, and these two segments are connected through a bithiophene moiety to shape a two-dimensional (2D) multibranched conjugated system. The molecule showed high thermal stability. It demonstrated good solubility in THF with an emission maximum at 470 nm, and excimer emission appeared in poor solvents such as aqueous media showing an obvious red-shift. A two-photon excited fluorescence (TPEF) test revealed that the maximal two-photon absorption (2PA) cross-section of the molecule was 1352 GM, which is comparable with the reported bipyrimidine-based multibranched compounds with a stronger donor. Theoretical calculation suggested that the molecule showed good coplanarity made up by two conjugated segments with a small dihedral angle. The charge transport ability of OSPB was preliminarily studied using an organic thin-film transistor (OTFT) device via a low-cost solution processing technique, and the results demonstrated that it was a p-type semiconductor. [ABSTRACT FROM AUTHOR]

A strongly electron-withdrawing benzo[c][1,2,5]oxadiazole (BOZ) unit, as the second electron acceptor segment, is incorporated into the naphthalenediimide (NDI) based polymer backbone for the first time. Therefore, a unipolar n-type polymer semiconductor (PNBO) with a regioregular A1–D–A2–D configuration is developed successfully. It is found that BOZ-containing polymer PNBO not only has a deep-lying LUMO energy level of ca.−4.0 eV, which facilitates electron-injection from an Au electrode into the active layer, but also possesses a deep enough low HOMO energy level of −5.9 eV for blocking hole-injection. The carrier transporting performance of PNBO is characterized by solution-processable polymeric field-effect transistors (PFETs). These results demonstrate that a smooth surface morphology and a compact solid stacking endow PNBO with excellent unipolar n-type electron-transporting characteristics; a highest electron mobility of up to 2.43 cm2 V−1 and an excellent shelf storage with a negligible decay in 70 days are achieved. [ABSTRACT FROM AUTHOR]

Exploring new hybrid catalysts to replace Pt-based catalysts for the hydrogen evolution reaction (HER) is important for various renewable energy applications. However, the design and synthesis of such catalysts are still challenging. Herein, we focus on the development of a series of hybrid materials consisting of cobalt nickel phosphide nanoparticles (NPs) decorated carbon nanotubes (Co2−xNixP/CNTs) as efficient catalysts for enhanced HER catalytic activity. All the X-ray spectra including X-ray diffraction, X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy demonstrate that the crystalline phase structure, valence and coordination environment of hexagonal Ni2P are changed with increasing Co atoms. Electrochemical measurements show that the Co2−xNixP/CNT hybrids exhibit high activity and stability for the HER in acidic solution. The as-synthesized Co1.6Ni0.4P/CNT hybrid exhibits the highest electrocatalytic activity with low onset overpotential (36.1 mV), a small Tafel slope (46.7 mV dec−1), a much larger exchange current density (1.86 × 10−5 A cm−2), lower HER activation energy (57.3 kJ mol−1), and good stability. Such enhanced catalytic activity originates from the introduction of Co and strong synergistic effects between CNTs and Co2−xNixP. Meanwhile, density functional theory calculations also confirm that the higher HER catalytic activity of the Co2−xNixP/CNTs can be attributed to the splendid migratory aptitude of adsorbed single H atoms and the lower energy barrier for H2 formation after the introduction of Co atoms. The as-synthesized Co2−xNixP/CNT hybrid catalysts have great potential practical application in water splitting. [ABSTRACT FROM AUTHOR]

Graphene, an amazing two-dimensional material with excellent physical properties, has attracted great attention in various disciplines. Both fundamental studies and applications require graphene samples with controlled parameters including their quality, size, crystallinity, layer number and so on. While graphene can be prepared by direct exfoliation from mother materials or growth on transition metals, the uncontrolled production or the additional complex transfer process has been challenging for graphene applications. Direct preparation on a desired dielectric substrate is an important research direction that potentially addresses these problems. Many advances have been made in the past few years, and this tutorial review provides a brief summary of ways of preparing graphene on dielectric substrates. Various methods including the annealing method, direct chemical vapor deposition graphene synthesis on conventional dielectric substrates and hexagonal boron nitride layers are systematically reviewed and discussed. The main problems and further directions in this field are also presented. [ABSTRACT FROM AUTHOR]

Cobalt phosphides have been used as promising electrocatalysts for catalyzing the hydrogen evolution reaction (HER) in acidic aqueous solutions. In order to further explore the influence of phase structure and support effect on the catalytic activity for HER, herein, a series of cobalt phosphide-based electrocatalysts, including Co2P, CoP, Co2P/CNTs, CoP/CNTs, Co2P/NCNTs and CoP/NCNTs, were synthesized successfully via a facile thermal decomposition approach. The crystalline phase can be controlled by changing the phosphide source species. When the phosphide source was trioctylphosphine, CoP-based catalysts were obtained. However, Co2P-based catalysts can be obtained by using triphenylphosphine as the phosphide source. Then the phase catalytic activity and stability of the as-synthesized cobalt phosphide-based catalysts for hydrogen evolution were compared. The results show that the catalytic activity followed the order CoP/NCNTs ＞ Co2P/NCNTs ＞ CoP/CNTs ＞ Co2P/CNTs ＞ CoP ＞ Co2P, which can be attributed to the different atomic ratios of Co to P, the strong interaction between cobalt phosphide and carbon species and the doping of N atoms into CNTs. Our studies indicate that the HER catalytic efficiency of transition metal phosphide catalysts can be improved significantly by adjusting active phase and carbon species structures. [ABSTRACT FROM AUTHOR]

In this paper, an efficient method to fabricate Al-based metal organic framework (Al-MOF) MIL-96 crystals with controllable size and morphology, by mixing other forms of reactants to replace the coordination modulators or capping agents, is presented. The size and morphology of the MIL-96 crystals can be selectively varied by simply altering the ratio of dual reactants via their hydrolysis reaction. All the samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and nitrogen sorption. Then based on the BFDH theory, a mechanism for the impact of hydrolysis of reactants on the crystal size and morphology is presented and discussed. We also evaluated the performance of these MOFs as sorbents for capturing CO2, and they all show enhanced adsorption properties compared with the bulk material, displaying high adsorption capacities on CO2 at atmospheric pressure and ambient temperature. [ABSTRACT FROM AUTHOR]

Designing efficient, stable and inexpensive electrocatalysts to replace Pt-based catalysts for the hydrogen evolution reaction (HER) is highly desired in renewable energy research. In this study, we report the synthesis of nickel phosphide nanoparticles decorated on multiwalled carbon nanotubes (Ni2P/CNT) by in situ thermal decomposition of nickel acetylacetonate as a nickel source and trioctylphosphine as a phosphorus source in oleylamine solution of CNT. As a novel HER electrocatalyst, the Ni2P/CNT nanohybrid exhibits excellent electrocatalytic activity in 0.5 M H2SO4 with a low onset overpotential (88 mV), a small Tafel slope (53 mV dec−1), a high exchange current density (0.0537 mA cm−2) and good stability. It only needs overpotentials of 98 and 124 mV to attain current densities of 2 and 10 mA cm−2, respectively. In addition, the Ni2P/CNT nanohybrid shows nearly 100% Faradaic efficiency in acid solutions. This work successfully demonstrates that the introduction of Ni2P NPs into CNT for enhanced electrocatalytic properties is feasible, and that this may open up a potential way for designing more efficient Ni2P-based catalysts for the HER. [ABSTRACT FROM AUTHOR]