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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.

Density functional theory based particle swarm optimization calculations were performed to identify magic-number structures of supported sub-nano Ni clusters and the influence of hydrogen coverage.

Donor engineering of diphenylamine-substituted tris(2,4,6-trichlorophenyl)methyl (TTM) radicals triggers the switching of the TTM-based radicals from the photoluminescent to NIR photothermal mode.

A Co tetra-capped Keggin crystalline Co4Mo12 was separated from the impregnating solution via a self-assembly strategy and used as a molecular platform to reveal the sulfidation procedure of a precursor in the construction of a superior HDS catalyst.

A multi-level spatial confinement strategy is proposed for the fabrication of ultra-dispersed 1T-Co-MoS2 nanoclusters, which exhibit remarkable electrocatalytic activity and durability for HER.

The NiN4–Cl SAs/N–C electrocatalyst consisting of NiN4–Cl active sites with axial Ni–Cl coordination was synthesized. The axial Cl-coordination modulates the electronic configuration of Ni–N4 sites and enhances the interaction of Ni–H efficiently.

Bifunctional Cu/MFI catalysts with balanced Cu0–Cu+ and Brønsted acid sites for robust selective ring-opening of furfuryl alcohol to pentanediol.

The solution-phase synthesis of (hetero)cycloarenes with a well-defined size and geometric structure remains a challenging topic in organic chemistry and materials science. Herein, two novel nonplanar N,S-heterocycloarenes (PTZ1 and PTZ2) containing two/three alternate phenothiazine

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.

A series of closed-shell kekulene homologues and an open-shell carbonylated cycloarene derivative were synthesized successfully by controlling the temperature and gas atmosphere of a Bi(OTf)3-catalyzed cyclization reaction.

A cyclopenta-fused macrocyclic tetraradicaloid, MC4-S, containing alternating phenanthrene (Phen) and dibenzo[b,d]thiophene (DBTh) units was synthesized and isolated in single-crystal form. Compared with its all-carbon isoelectronic structure, CPTP-M, the incorporation of two sulfur atoms leads to a smaller radical character and a larger singlet–triplet energy gap. X-ray crystallographic analysis reveals that the spin–spin coupling through the DBTh unit is stronger than that through the Phen moiety. In addition, the electron-rich sulfur atoms also raise the energies of both the HOMO and LUMO in MC4-S, but the overall optical and electronic energy gaps are close to that of the CPTP-M. MC4-S displays global anti-aromaticity according to the NMR measurements and theoretical calculations (NICS, ACID and 2D ICSS), with a 36π ring current circuit along the all-carbon periphery excluding the two sulphur atoms. Its dication becomes globally aromatic due to the existence of a dominant 34π-conjugation pathway. This study sheds some light on the effect of heteroatoms on the electronic properties of open-shell polyradicaloids.

Ni/ZnO catalysts have been well recognized by industry and academia for exhibiting excellent desulfurization activities. However, the intrinsic reaction mechanism on the Ni active center is still obscure. Herein, we performed periodic density functional theory (DFT) calculations to study thiophene desulfurization and conversion of desulfurization products on the Ni(111) surface and Ni55 cluster, and clarify the size effect of the Ni substrate and the essential role of hydrogen. The thiophene molecule binds more strongly to Ni55 than Ni(111), and proceeds easily along the direct desulfurization pathway without prior hydrogenation on both Ni(111) and Ni55. Ni55 exhibits higher desulfurization activity while Ni(111) performs better in converting the remaining C4H4 species to butadiene and the deposited S atom to H2S. In contrast to the classic S transfer mechanism via H2S, we found that direct S diffusion occurs easily on the Ni substrate and has priority over its further hydrogenation to H2S, indicating that the S diffusion mechanism could play an important role in transferring surface S from Ni to ZnO. The results also show that the C–S bond rupture of thiophene and subsequent S removal from Ni tend to proceed without the assistance of hydrogen, and hydrogen mainly takes part in the hydrogenation of C4H4 species. The present work clearly demonstrates that the rate-determining step for thiophene desulfurization and subsequent alkene formation is the C4H4 hydrogenation rather than the cleavage of C–S bonds, in accordance with the experimental results.

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.

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.

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.

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.

The chemical vapour deposition (CVD) method has offered a new possibility of preparing metal–organic frameworks (MOFs). However, the reported MOF-CVD method is limited to the use of gaseous organic precursors, preventing the extension of the CVD method to a broad range of potential organic linkers. This study, for the first time, reports a dual-temperature zone CVD-assisted approach for the in situ growth of conductive Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) nanowire arrays (NWAs) on the interface between a solid Cu foil and a solid organic precursor, overcoming the difficulties of high sublimation temperatures of organic ligands and low decomposition temperatures of conductive MOFs. In the process, oxygenated water (O-H2O) is the key to obtain crystalline Cu3(HHTP)2 NWAs, and the growth is described by a base-growth mode. A symmetrical supercapacitor based on Cu3(HHTP)2 NWAs on the Cu foil shows a high specific surface area normalized capacitance of 41.1 μF cm−2 for 0.5 A g−1, which is 2–5 times higher than those of most carbon materials. This study demonstrates the extension of the synthesis method from the previous liquid or gas based reaction to a solid–solid reaction, and this extension is expected to be very useful for the production of a broad range of conductive MOFs and their direct supercapacitor application.

Polymeric semiconductors have attracted a lot of attention in the field of organic field-effect transistors (OFETs) due to their potential application in solution-processable flexible electronics. In order to get high performance polymers that meet industry requirements, green polymerization methods and processing strategies are highly desired. Although organostannanes are highly efficient in polymerization, their toxic properties limit their application. For example, Suzuki–Miyaura crossing coupling was first suggested as a replacement of the Stille reaction for its environmentally benign nature of boron reagents. Moreover, direct (hetero)arylation polycondensation (DHAP) has been established as a straightforward method for the preparation of conjugated polymers. Additionally, aldol polycondensation was recently reported as a new route, as it requires neither organometallic monomers nor transition metal catalysts. For potential applications, not only is green synthesis needed, but also eco-friendly processing. In order to avoid the use of halogenated solvents, two major tactics are used: reducing intermolecular interactions and enhancing solute–solvent interactions. In this review, we aim to introduce green synthetic methods as well as environmentally benign processing strategies providing some ideas for the totally green fabrication of electronic devices.

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 (

Organic semiconductors for electronic devices have attracted much attention in scientific research and industrial applications. In the past few decades, functional organic field-effect transistors (OFETs) have developed rapidly, especially OFETs with memory function. Here, through a detailed introduction of the background, memory mechanism and structure construction, we make a comprehensive summary of memory applications based on OFETs. Further, we describe four types of OFET memories, i.e. floating-gate OFET memory, electret OFET memory, ferroelectric OFET memory, and optoelectronic OFET memory. Finally, we put forward challenges in the development of OFET memory and look forward to the future trend of the development of OFET memory.

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.

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.

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.

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.

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.

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.

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.

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).

This paper proposes a new approach for investigating the mechanism of the formation of the active phase of a hydrodesulfurization (HDS) catalyst via crystalline polyoxometalate (POM) precursors. The proposed strategy induces the crystallization of small Ni–Mo–O clusters in an impregnating solution by the coordinate bonding and supramolecular interaction of organic ligands to form POMs. By exploiting the “ligand-induced self-assembly” strategy, two Ni–Mo binary POMs with different frameworks, namely, Mo2Ni and PMo11Ni, were isolated from the impregnating solution by means of 4,4′-bpy. The sulfidation process of the precursors and the formation mechanism of the NiMoS active phase were fully characterized by a multi-technique approach that comprised, in particular, in situ FT-IR spectroscopy, XRD and Raman spectroscopy for different degrees of sulfidation. The results of the characterization revealed the structure-directing effects (framework effect, promoting effect and ligand effect) of the POM precursors on the structure of the active phase and even its HDS performance. MoS2 was formed at 200 °C from Mo2Ni, and the Ni species interacted with the edges of MoS2 to form the NiMoS active phase, whereas PMo11Ni formed MoS2 at 300 °C. The structure-directing effects enabled a higher content and better dispersion of the NiMoS active phase, which explains the higher HDS reactivity of sulfided Mo2Ni. The bottom-up self-assembly approach not only provides a better understanding of the composition of the impregnating solution and the formation mechanism of the NiMoS active phase but also sheds light on the rational design and controllable preparation of NiMoS catalysts with high performance.

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.

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.

Donor–acceptor (D–A) type conjugated polymers have been extensively studied for organic field-effect transistors (OFETs), while the homopolymers of acceptors were much less investigated. However, conjugated homopolymers are structurally simpler, so their solid-phase behavior such as packing pattern, long-range order and crystallinity are more predictable, so are their charge-transport properties. Here we report the synthesis of the homopolymer of thiophene-fused isoindigo (TII), which was directly obtained using a “one-pot” polymerization method either via Suzuki condensation polymerization (denoted as PTII-1) or Stille condensation polymerization (denoted as PTII-2), respectively. To further elucidate the structure–property relationship of the PTII, TII was also copolymerized with II to give P(TII-co-II) for comparison. Encouragingly, solution-processed OFETs based on PTII-2 exhibited ambipolar transport behavior with balanced hole and electron mobilities (0.065 and 0.15 cm2 V−1 s−1, respectively) after annealing, which is two orders higher than that of P(TII-co-II). 2D grazing incidence X-ray diffraction (2D-GIXRD) analysis explicitly showed that PTII films have much better well-ordered structure and crystallinity than P(TII-co-II), which accounted for their better OFET performance. To the best of our knowledge, PTII-2 is among the best homopolymers of A units with high ambipolar charge-carrier mobility, indicating that the design of such homopolymers might be an important strategy toward high performance polymer OFETs. In addition, the “one-pot” homopolymerization of dibromo-monomers via Suzuki or Stille condensation also provides a more convenient way to construct conjugated homopolymers, which deserves a closer study.

Five D–A (donor–acceptor) copolymers P1–P5 were designed and synthesized, with the mainchain constructed with thiophene derivatives as D and a quinoxaline unit as A, and the sidechain constructed with alkyl groups or alkylthienyl groups. All the polymers showed good thermal stability for device fabrication. The absorption spectra revealed that the five polymers covered a wide absorption range from 300 to 727 nm (with P1), and to 755 nm (with P5). Characterization results showed that both the mainchain and sidechain structures played important roles in the optical, electronic and charge transport properties. OTFT devices were fabricated to evaluate the mobilities of copolymers, and P3 with benzodithiophene and quinoxaline moieties as the mainchain and pure linear alkyl groups as the sidechain manifested the best performance.

Many strategies, such as doping metal, designing low-dimensional nanostructures, and enhancing the utilization of active sites based on a conductive support, have been intensively pursued to improve the intrinsic activity of transition metal chalcogenides for the hydrogen evolution reaction (HER). However, integrating all the above-mentioned merits into one electrocatalyst is still a significant challenge. Herein, we have successfully prepared uniform CoMoS/CoMoO4 (CMS) shell–core nanorods, with a diameter of 60 nm and a length of 800 nm, supported on N-doped reduced graphene oxide (NRGO). The obtained CMS/NRGO can combine many advantages, including transition metal doping, one-dimensional nanorods, and the superior conductivity of NRGO, resulting in very promising HER properties and excellent stability. The optimum sulfurization temperature for unsupported CMS nanorods has been explored using uniform CoMoO4 nanorods as a precursor. Although CMS-3 prepared with a sulfurization temperature of 300 °C has been found to possess the optimum activity for the HER, when adopting NRGO as a support, CMS-3/NRGO exhibits an impressive enhancement in HER performances with a low overpotential of 80 mV, a small Tafel slope of 58 mV dec−1, and a large exchange current density of 428 μA cm−2. In addition, the electrocatalytic activity of CMS-3/NRGO shows a negligible delay after 1000 cycles, indicating its robust electrochemical stability in acid electrolyte solution. Therefore, adopting low-temperature sulfurization of one-dimensional metal oxide precursors supported on NRGO may be a promising strategy for obtaining excellent electrocatalysts for the HER.

Growth control over the size and shape of two-dimensional hexagonal boron nitride domains is vital for its applications. Here we develop a rational water-assisted chemical vapor deposition method that allows fast growth of large-sized (more than 330 μm) single crystal domains, which are 3–5 times larger than those previously grown on solid Cu or Cu–Ni alloy. Further kinetic control results in the perfect evolution of the domain shape from negatively curved triangle, triangle, positively curved triangle, regular hexagon, polygon, to circle. This work addresses the existing major problems, paving a way for the synthesis of materials with better control.

To date, versatile polymer semiconductors have been reported for field-effect transistors (FETs). And the third-generation donor–acceptor (D–A) polymers have been among the most intensively studied semiconductors. Meanwhile, there are a variety of methods adopted for the enhancement of performance. To the best of our knowledge, a p-type polymer semiconductor with a highest hole mobility of 52.7 cm2 V−1 s−1, an n-type polymer semiconductor with a highest electron mobility of 8.5 cm2 V−1 s−1 and a balanced ambipolar semiconductor with the highest both hole and electron mobility of over 4 cm2 V−1 s−1 have been achieved. This review describes building block selection, backbone halogenation, side chain engineering and random copolymerization, which are the effective synthesis approaches applied in this field, affording assistance for developing high-performance polymer semiconductors in the future.

Correction for ‘Perovskite photodetectors and their application in artificial photonic synapses’ by Xin Huang et al., Chem. Commun., 2021, DOI: 10.1039/d1cc04447h.

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.

Spindle-like boehmites with high adsorption capacity for Congo red (CR) from water were prepared via a hydrothermal synthesis method without any surfactants. The crystallite sizes of boehmites can be subtly adjusted by hydrothermal post-treatment for various durations, and the crystalline structure, morphology and textural properties of boehmites were characterized by different techniques. The adsorption capacities and rates of CR onto boehmites were thoroughly evaluated with the help of equilibrium and kinetics experiments. The adsorption isotherms are fitted well to the Langmuir equation, and the Langmuir adsorption capacity (qmax) is as high as 427.4 mg g−1. The kinetics data show that the adsorption process can be well described by pseudo-second-order kinetics model, and besides, adsorption rate is closely related to the exposed surface area of lattice plane (020) of boehmite crystallite, because this plane has a relatively high OH density that is favourable to the adsorption of CR. The IR characterization and the relationship between the pH values of the zero point of charge (pHzpc) for different boehmites and adsorption behavior of CR suggest that the involved adsorption process is driven by the hydrogen bonding and electrostatic attraction at the same time.

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.

Novel three dimensional (3D) electrodeposited Co–P nanosphere arrays on FTO (Co–P/FTO) have been successfully prepared as efficient bifunctional electrocatalysts for overall water splitting in alkaline media. The morphologies and properties of the 3D Co–P nanosphere arrays can be controlled by the electrolyte concentration. At the middle concentration, Co–P nanospheres have a more homogeneous size and array distribution and a rough surface, implying a larger surface area and an increased number of active sites for water splitting. The electrochemical measurements confirm the best electrocatalytic performances of Co–P/FTO at the middle concentration. They show excellent activity, with an overpotential of 125 mV for HER, 420 mV for OER and Tafel slopes of 54 mV dec−1 and 83 mV dec−1, respectively. The fabricated bifunctional systems of Co–P/Co–P can efficiently catalyse HER and OER at the same time, solving the incompatible problem of different media between HER and OER. Therefore, controlling the synthesis of 3D Co–P/FTO nanosphere arrays through electrodeposition can provide a facile way for the bifunctional electrocatalysis of both HER and OER.

A novel and highly active hybrid catalyst for the hydrogen evolution reaction (HER) is constructed by the in situ growth of CoP on the surface of MoS2 and CNTs. The CoP/MoS2-CNTs hybrid catalyst exhibits Pt-like catalytic activity for the HER with an overpotential close to zero, a Tafel slope of 42 mV dec−1 and good stability, which is the best among all non-noble metal catalysts.

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.

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.

Mesoporous alumina with different morphologies was synthesized via thermal decomposition of the Al-based metal–organic frameworks (Al-MOFs) MIL-110 and MIL-100, in which Al-MOFs were used as the Al source and precursor. The hexagon rod-shaped and octahedron-shaped alumina products with morphology retained from their precursors were obtained and characterized. The results show that the construction of Al-MOFs, especially the aluminium building units plays a key role in the textural structure of the obtained alumina products. Besides, the differences in textural properties as well as the possible formation mechanism of the final alumina products are well explained by taking into account thermal behaviour and intrinsic structure features, especially the aluminium building units, of the Al-MOFs precursors. This work presents an easy new method to produce alumina with tailored morphology, tunable texture and microstructure, which is also an operational method fit for other metal oxide materials.

Monodispersed nickel phosphide nanocrystals (NCs) with different phases (Ni12P5, Ni2P and Ni5P4) were synthesized via the thermal decomposition approach using nickel acetylacetonate as the nickel source, trioctylphosphine as the phosphorus source and oleylamine in 1-octadecene as the reductant. The phases of the as-synthesized nickel phosphide NCs could easily be controlled by changing the P : Ni precursor ratio. The structure and morphology of the as-synthesized nickel phosphide NCs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption–desorption. A formation mechanism for the as-synthesized nickel phosphide NCs was proposed. We further studied the influence of the phase of the nickel phosphide NCs on the electrocatalytic properties for the hydrogen evolution reaction (HER). All phases showed good catalytic properties, and the Ni5P4 NCs with a solid structure exhibited higher catalytic activity than the Ni12P5 and Ni2P NCs. This superior catalytic activity is attributed to the higher positive charge of Ni and a stronger ensemble effect of P in Ni5P4 NCs. This study demonstrates that the crystalline phase is important for affecting the electrocatalytic properties.

We developed a synthetic strategy for enhancing organic thin-film transistor performances of polymer semiconductors through the modification of the side chain to optimize the stacking conformation and the conjugated backbone to decrease the π–π stacking distance of polymers. Our studies demonstrate that the role of bulky alkyl chains attached to the donor unit or the acceptor unit is especially crucial for molecular stacking and aggregation and thus the OTFT device performance of polymers. However, with a larger π–π stacking distance in the thin film, the polymer with a bulky alkyl chain attached at the acceptor (P2) shows almost two orders of magnitude higher mobility than that with a bulky alkyl chain attached at the donor (P1). The better performance for P2 is attributed to the bulky alkyl chain at the acceptor which allows more coplanarity of the P2 backbone in the solution state, which leads to self-assembly, and finally forms a highly ordered layer-by-layer lamellar packing for P2 during spin-coating. Further improved performances were obtained by introducing two thiophene units into the polymer backbone to give P3, due to closer π–π stacking and in-plane π-stacking alignment in the thin film and a higher HOMO energy level. Therefore, an optimized device performance was realized through subtle modification of the polymer structure, including both the main chain and the side chain, which provides an insight into structure–property relationships for high-mobility polymer semiconductors.

Nanostructured nickel sulfide with different phases was synthesized via a thermal decomposition approach using nickel acetylacetonate as the nickel source, 1-dodecanethiol as the sulfur source and oleylamine as the high boiling solvent. The phase evolution of nickel sulfide nanocrystals (NCs) can be easily achieved by changing the molar ratio of Ni : S precursor and the species of the solvent. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption were used to characterize the as-synthesized nickel sulfide NCs. The electrocatalytic activity and stability of the as-synthesized nickel sulfide NCs for the hydrogen evolution reaction (HER) were investigated. Due to the different crystalline phase structures of the as-synthesized nickel sulfide NCs, the β NiS NCs exhibit better electrocatalytic activity with a low onset overpotential (186 mV), a small Tafel slope (51.2 mV dec−1), a high exchange current density (2.4 × 10−6 A cm−2), a large electrochemical double-layer capacitance (2.7 mF cm−2) and improved stability than the Ni7S6 and α NiS + β NiS NCs for HER. This study provides a good strategy for designing more efficient nickel sulfide catalysts for the HER.

An efficient method was developed for the synthesis of nickel phosphide nanocrystals (NCs) via thermal decomposition of bis(triphenylphosphine)nickel dichloride (BTND) precursor in the presence of oleylamine (OAm) for the first time. The effect of synthetic conditions such as reaction temperature, reaction time and OAm quantity on the size and phase of the as-synthesized nickel phosphide NCs was discussed. The structure and morphology were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption measurements. The results showed that the size of Ni2P NCs can be controlled by increasing reaction temperature and OAm quantity. The phase of nickel phosphide NCs can be controlled by changing the reaction time. The shorter reaction time was beneficial for forming Ni12P5 NCs, and longer reaction time was beneficial for forming Ni2P NCs. Furthermore, a possible growth mechanism of the as-synthesized nickel phosphide NCs was proposed. These synthetic techniques may be expanded to other metal phosphide materials.

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.