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Ultrathin organic nanofibers (UTONFs) represent an emerging class of nanomaterials as they carry a set of favorable attributes, including ultrahigh specific surface area, lightweight, and mechanical flexibility, over inorganic counterparts, for use in biomedicine and nanotechnology. However, precise synthesis of uniform UTONFs (diameter ≤ 2 nm) with tailored functionalities remained challenging. Herein, we report robust multifunctional UTONFs using hydrophobic interaction-driven self-assembly of amphiphilic alternating peptoids containing hydrophobic photoresponsive azobenzene and hydrophilic hydroxyl moieties periodically arranged along the peptoid backbone. Notably, the as-crafted UTONFs are approximately 2 nm in diameter and tens of micrometers in length (an aspect ratio, AR, of ∼10000), exemplifying the UTONFs with the smallest diameter yielded via self-assembly. Intriguingly, UTONFs were disassembled into short-segmented nanofibers and controllably reassembled into UTONFs, resembling “step-growth polymerization”. Photoisomerization of azobenzene moieties leads to reversible transformation between UTONFs and spherical micelles. Such meticulously engineered UTONFs demonstrate potential for catalysis, bioimaging, and antibacterial therapeutics. Our study highlights the significance of the rational design of amphiphiles containing alternating hydrophobic and hydrophilic moieties in constructing otherwise unattainable extremely thin UTONFs with ultrahigh AR and stimuli-responsive functionalities for energy and bionanotechnology.

Photocatalysis offers a direct, yet robust, approach to eradicate pathogenic bacteria. However, the practical implementation of photocatalytic disinfection faces a significant challenge due to low-efficiency photogenerated carrier separation and transfer. Here, we present an effective approach to improve photocatalytic disinfection performance by exploiting the pyro-phototronic effect through a synergistic combination of pyroelectric properties and photocatalytic processes. A set of comprehensive studies reveals that the temperature fluctuation-induced pyroelectric field promotes photoexcited carrier separation and transfer and thus facilitates the generation of reactive oxygen species and ultimately enhances photocatalytic disinfection performance. It is worth highlighting that the constructed film demonstrated an exceptional antibacterial efficiency exceeding 95% against pathogenic bacteria under temperature fluctuations and light irradiation. Moreover, the versatile modulation role of the pyro-phototronic effect in boosting photocatalytic disinfection was corroborated. This work paves the way for improving photocatalytic disinfection efficiency by harnessing the synergistic potential of various inherent material properties.

Graphical abstract: The combination ofin-situgrowth synthesis with precise compositional and interfacial chemistry control, and in-depth characterization enables the understanding and new developments of two-dimensional heterostructured architectures with programmed organization and enhanced properties for a variety of critical materials applications.

The ability to direct semiconducting polymers and inorganic nanomaterials into complex assemblies renders the creation of organic–inorganic nanocomposites with unique properties and functionalities. Herein, we report the crafting of highly interconnected semiconducting organic–inorganic nanocomposites (referred to as nanojunctions) comprising long poly(3-hexylthiophene) (P3HT) nanowires and lead telluride (PbTe) quantum dots (QDs) via two successive self-assembly processes. First, P3HT chains self-assemble into ultralong one-dimensional (1D) nanowires owing to interchain π–π stacking, followed by self-assembly of PbTe QDs on both sides of the P3HT nanowires driven by attractive van der Waals interactions between the hexyl side chains of P3HT and aliphatic chains capped on the surface of PbTe QDs. Notably, an integrated experimental and Monte Carlo (MC) simulation study reveals that the surface coverage of PbTe QDs within the P3HT/PbTe nanojunctions as well as the distance between adjacent PbTe QDs could be conveniently tailored via tuning the QD concentration. Interestingly, the photoluminescence of P3HT progressively decreases with an increased loading of PbTe QDs because of effective charge transfer from P3HT to PbTe. Conceptually, this two-step self-assembly strategy can be readily extended to other semiconducting polymers and a diversity of nanomaterials for potential applications in optoelectronic materials and devices.

The past decades have witnessed rapid development of lithium-based batteries. Significant research efforts have been progressively diverted from electrodes to electrolytes, particularly polymer electrolytes (PEs), to tackle the safety concern and promote the energy storage capability of batteries. To further increase the ionic conductivity of PEs, various branched polymers (BPs) have been rationally designed and synthesized. Compared with linear polymers, branched architectures effectively increase polymer segmental mobility, restrain crystallization, and reduce chain entanglement, thereby rendering BPs with greatly enhanced lithium transport. In this Mini Review, a diversity of BPs for PEs is summarized by scrutinizing their unique topologies and properties. Subsequently, the design principles for enhancing the physical properties, mechanical properties, and electrochemical performance of BP-based PEs (BP-PEs) are provided in which the ionic conduction is particularly examined in light of the Li+transport mechanism. Finally, the challenges and future prospects of BP-PEs in this rapidly evolving field are outlined.

Despite recent progress in synthesis, self-assembly, and utility of low band gap lead chalcogenide nanoparticles (NPs) due to their intriguing optoelectronic characteristics, their compositional instability in ambient condition remains a great challenge for long-term practical applications. Herein, we report a unique strategy via capitalization on a set of starlike block copolymers as nanoreactors for in situ crafting of uniform lead chalcogenide NPs with readily tailored sizes, surface chemistry, near-infrared (NIR) optoelectronic properties, and more importantly, markedly enhanced stability against air exposure. The intimate and permanent tethering of the outer blocks of starlike block copolymers on the surface of lead chalcogenide NPs imparts their effective dispersion in both the solution and dry state. The diameter of the resulting NPs can be conveniently tuned by regulating the molecular weight (i.e., length) of the inner hydrophilic blocks of starlike block copolymers, manifesting the progressive red shift in the NIR absorption and emission as the diameter of the NPs increases. Most intriguingly, judiciously alternating the compositions and chain lengths of the outer blocks of the starlike block copolymers renders remarkably improved stability of lead chalcogenide NPs in ambient condition, representing no spectral change in both position and intensity for 30 days as compared to rapid and complete quenching of emission in 1 day in conventional small-molecular-ligand-capped counterparts. In principle, our starlike block copolymer nanoreactor strategy can be easily extended to synthesize functional NPs other than metal chalcogenides for investigation into their dimension-dependent physical properties and self-assembly as well as various applications.

Parkinson’s disease (PD) is a neurodegenerative disease with dopaminergic neurons loss, which induces dopamine reduction and body motion disorder. Traditional deep brain stimulation (DBS), which involves the implanting metal electrodes into the subcortical nucleus of the brain, has a huge risk of invasive surgery and low resolution. Here we present that pomegranate-like piezoelectric nanogenerators are able to efficiently transduce ultrasonic wave into electric power generation under ultrasound stimulation, which modulates intracellular calcium signaling and tyrosine hydroxylase levels to activate the neuron activity and process of deep-brain tissue in vitroand in vivo. Strikingly, after one-week nanogenerator-mediated neuromodulation, the damaged dopaminergic neurons in PD-zebrafish and mice were reversed with a decrease in α-synuclein aggregates and an increase in tyrosine hydroxylase for neuronal recovery of PD. The behaviors of PD mice model also have a significant improvement, compared with untreated group. This approach provides a minimally invasive and high precision neurotechnology protect against neuronal death and loss of synapse in PD and other neurodegenerative diseases.

Whispering gallery mode resonators have been demonstrated to be a great way to achieve superior optical cavities with high quality factor and small mode volume. However, due to the high sensitivity of these modes to the properties of the resonator boundary, they are susceptible to parasitic splitting of clockwise and counterclockwise modes. In this work, we investigate the effect of implantation of an engineered notch into the boundary of a circular microdisk resonator fabricated from colloidal quantum dots, which are particularly sensitive to boundary defects. We observed a strong reduction of parasitic mode splitting with introduction of a large engineered notch, as well as enhanced directionality of laser emission. We further investigate the performance of these resonators in evanescently coupled pairs, where the modal interaction allows modulation of laser behavior through variation of the gain and loss induced by the optical pump. We show that two distinct cases of modal interaction can be achieved by adjusting the size of the engineered notch, providing a bridge between intra- and interdisk modal interactions for laser spectral control.

The ability to create perovskite-based heterostructures with desirable charge transfer characteristics represents an important endeavor to render a set of perovskite materials and devices with tunable optoelectronic properties. However, due to similar material selection and band alignment in type-II and Z-scheme heterostructures, it remains challenging to obtain perovskite-based heterostructures with a favorable electron transfer pathway for photocatalysis. Herein, we report a robust tailoring of effective charge transfer pathway in perovskite-based heterostructures via a type-II to Z-scheme transformation for highly efficient and selective photocatalytic CO2reduction. Specifically, CsPbBr3/TiO2and CsPbBr3/Au/TiO2heterostructures are synthesized and then investigated by ultrafast spectroscopy. Moreover, taking CsPbBr3/TiO2and CsPbBr3/Au/TiO2as examples, operando experiments and theoretical calculations confirm that the type-II heterostructure could be readily transformed into a Z-scheme heterostructure through establishing a low-resistance Ohmic contact, which indicates that a fast electron transfer pathway is crucial in Z-scheme construction, as further demonstrated by CsPbBr3/Ag/TiO2and CsPbBr3/MoS2heterostructures. In contrast to pristine CsPbBr3and CsPbBr3/TiO2, the CsPbBr3/Au/TiO2heterostructure exhibits 5.4- and 3.0-fold enhancement of electron consumption rate in photocatalytic CO2reduction. DFT calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy unveil that the superior CO selectivity is attributed to the lower energy of *CO desorption than that of hydrogenation to *HCO. This meticulous design sheds light on the modification of perovskite-based multifunctional materials and enlightens conscious optimization of semiconductor-based heterostructures with desirable charge transfer for catalysis and optoelectronic applications.

Designing confined catalysis by harnessing “confinement effects”, defined as the modulated microenvironments and physical properties that alter reaction kinetics and selectivity induced by placing active sites into confined regions, is becoming increasingly important as a complement to traditional catalyst design strategies. This comprehensive review aims to provide an in-depth understanding of how and why “confinement effects” impact the process of energy conversion electrochemical reactions. Firstly, fundamental principles underlying the catalytic performance enhanced by “confinement effects”, including electronic structure perturbation, charge transfer acceleration, active sites stabilization, solvent properties modulation, and mass transport regulation will be introduced. Subsequently, a systematic analysis of advanced strategies for constructing confined catalysts will be conducted. We scrutinize advances in the design and implementation of confined catalysts for electrochemical reactions from three different dimensionalities, namely activity optimization, durability enhancement, and selectivity modulation. Finally, future research opportunities that merit heightened consideration to foster the proliferation of confined catalysis are also proposed. This review offers profound insights into the further exploitation of “confinement effects” for pursuing catalysts with exceptional performance, which is of pivotal importance in stimulating more innovations regarding on the energy conversion reactions.

A bolaamphiphile possessing a hydrophobic skeleton and two hydrophilic groups at both ends represents an important class of building blocks toward a rich variety of self-assembled materials for use in ion transport, optoelectronic devices, and drug and gene delivery. Herein, we report a one-stepsynthesis of an array of rationally designed anionic bolaamphiphiles and unravel the correlation between molecular structure of anionic bolaamphiphiles and their disparate self-assemblies viasynergistic and meticulous tailoring of a set of interactions. Intriguingly, by delicately regulating the interactions among these supramolecular interactions, two-dimensional (2D) nanosheets are crafted viaself-assembly of anionic bolaamphiphiles. Particularly, single-layered 2D nanosheets are formed through the synergy of aromatic π–π stacking, hydrophobic, hydrogen-bonding, and electrostatic repulsion interactions. In contrast, the selective converting of anionic headgroups of bolaamphiphiles into nonpolar alkyl chain screens the electrostatic repulsion between neighboring bolaamphiphiles while keeping the other segments of bolaamphiphiles intact, thereby allowing them to self-assemble into multilayered 2D nanosheets. Interestingly, the intrinsically charged 2D nanosheets could anchor oppositely charged metal nanoparticles viaelectrostatic attraction. Conceptually, anionic bolaamphiphile-derived 2D nanosheets may function as a substrate to position a diversity of nanocrystals and conjugated polymers for a broad range of applications in catalysis, optical devices, and photothermal therapy.

The past several decades have witnessed substantial advances in synthesis and self-assembly of inorganic nanocrystals (NCs) due largely to their size- and shape-dependent properties for use in optics, optoelectronics, catalysis, energy conversion and storage, nanotechnology, and biomedical applications. Among various routes to NCs, the nonlinear block copolymer (BCP) nanoreactor technique has recently emerged as a general yet robust strategy for crafting a rich diversity of NCs of interest with precisely controlled dimensions, compositions, architectures, and surface chemistry. It is notable that nonlinear BCPs are unimolecular micelles, where each block copolymer arm of nonlinear BCP is covalently connected to a central core or polymer backbone. As such, their structures are static and stable, representing a class of functional polymers with complex architecture for directing the synthesis of NCs. In this review, recent progress in synthesizing NCs by capitalizing on two sets of nonlinear BCPs as nanoreactors are discussed. They are star-shaped BCPs for producing 0D spherical nanoparticles, including plain, hollow, and core–shell nanoparticles, and bottlebrush-like BCPs for creating 1D plain and core/shell nanorods (and nanowires) as well as nanotubes. As the surface of these NCs is intimately tethered with the outer blocks of nonlinear BCPs used, they can thus be regarded as polymer-ligated NCs (i.e., hairy NCs). First, the rational design and synthesis of nonlinear BCPs viacontrolled/living radical polymerizations is introduced. Subsequently, their use as the NC-directing nanoreactors to yield monodisperse nanoparticles and nanorods with judiciously engineered dimensions, compositions, and surface chemistry is examined. Afterward, the intriguing properties of such polymer-ligated NCs, which are found to depend sensitively on their sizes, architectures, and functionalities of surface polymer hairs, are highlighted. Some practical applications of these polymer-ligated NCs for energy conversion and storage and drug delivery are then discussed. Finally, challenges and opportunities in this rapidly evolving field are presented.

The ability to restrict the shuttle of lithium polysulfide (LiPSn) and improve the utilization efficiency of sulfur represents an important endeavor toward practical application of lithium–sulfur (Li–S) batteries. Herein, we report the crafting of a robust 3D graphene-wrapped, nitrogen-doped, highly mesoporous carbon/sulfur (G-NHMC/S) hierarchical aerogel as an effective polysulfide confinement matrix for a highly stable Li–S battery. Rich polar sites of NHMC firmly anchor LiPSnon the matrix surface. Porous NHMC provides ample space for accommodating sulfur and cushioning its volume expansion. Moreover, graphene wrapped on NHMC/S not only physically hinders the LiPSnshuttle but also interconnects the isolated NHMC/S, thus increasing electron transfer rate. Taken together, triple confinement of G-NHMC/S aerogel synergistically retains the soluble LiPSnand displays a specific capacity of 1322 mAh g–1and 1000-cycle life. As such, rationally designed 3D carbon/sulfur aerogel affords a unique platform to impart high energy density and stable electrodes for energy storage devices.

A series of amphiphilic star-like triblock copolymers with well-defined molecular architectures, molecular weight, and narrow polydispersity were successfully synthesized by sequential atom transfer radical polymerization (ATRP) using β-cyclodextrin as the initiator. These star-like triblock copolymers are composed of poly(4-vinyl pyridine) (P4VP) as the first block, poly(tert-butyl acrylate) (PtBA) as the second block, and either polystyrene (PS), poly(methyl methacrylate) (PMMA), or poly(ethylene oxide) (PEO) as the third block (denoted as P4VP-b-PtBA-b-PS, P4VP-b-PtBA-b-PMMA, and P4VP-b-PtBA-b-PEO, respectively). Notably, by deliberate addition of a linear initiator [i.e., ethyl α-bromoisobutyrate (EBiB)] into the polymerization reaction when growing the second PtBA block (i.e., synthesis of star-like P4VP-block-PtBA; denoted as P4VP-b-PtBA), a suitable concentration of Cu2+can be achieved. This suppresses further termination reactions between active chain ends of star-like polymer, thus rendering the ability to better control the growth of star-like P4VP-b-PtBA diblock copolymer (polydispersity index; PDI < 1.2). Kinetic studies of PtBA polymerization with and without the addition of linear initiators of EBiB were conducted. Importantly, the living nature of ATRP of star-like P4VP-b-PtBA diblock copolymer can only be attained when the linear initiator was added. Subsequently, star-like P4VP-b-PtBA-b-PS, P4VP-b-PtBA-b-PMMA, and P4VP-b-PtBA-b-PEO were synthesized by using star-like P4VP-b-PtBA as the macroinitiator via ATRP (for hydrophobic PS and PMMA) and click reaction (for hydrophilic PEO), respectively, further confirming the tunability of surface chemistry (i.e., the outer block of star-like triblock copolymers) in this system. Finally, after hydrolyzing PtBA into poly(acrylic acid) (PAA), the dual pH-responsive behaviors of double hydrophilic star-like P4VP-b-PAA diblock copolymer were explored. In addition to dual pH-responsiveness, the strategy we developed based on sequential ATRP via cyclodextrin as the initiator in this study may conveniently enable the synthesis of a rich variety of other stimuli-responsive unimolecular star-like block copolymers comprising dissimilar blocks that are either pH-responsive, thermo-responsive, or photo-responsive. As such, they may afford a unique platform for fundamental research and applications in smart delivery vehicles, sensors, and tunable templates for nanomaterials.

The rational design and facile synthesis of metal organic framework (MOF)-derived carbon materials with high oxygen reduction reaction (ORR) activity still remains challenging. Herein, we report on a simple yet robust route to dual-shelled Co, N, and S co-doped hollow carbon nanocages (denoted Co-N/S-DSHCN) with outstanding ORR performance. The concurrent compositional and structural engineering of the zeolitic imidazolate framework (ZIF-67), enabled by its coating with trithiocyanuric acid (TCA), yields core-shelled precursor particles which are subsequently carbonized into Co-N/S-DSHCN. Notably, Co-N/S-DSHCN-3.5 outperforms the commercial Pt/C, representing a +25 mV onset potential (Eon) and a +43 mV half-wave potential (E1/2) in 0.1 M KOH and a comparable E1/2to Pt/C in 0.5 M H2SO4, respectively. Such impressive ORR activities of Co-N/S-DSHCN-3.5 originate from the effective synergy of Co, N, and S co-doping (i.e., a compositional tuning) in conjunction with a unique dual-shelled hollow architecture containing hierarchical porosity (i.e., a structural tailoring).

Halide perovskite CsPbBr3quantum dots (QDs) were synthesized via supersaturated recrystallization process and deposited on the surface of TiO2microtubes forming local nano-heterostructures. Structural, morphological, and optical characterizations confirm the formation of heterostructures comprised of TiO2microtube decorated with green-emitting CsPbBr3nanocrystals. Optical characterizations reveal the presence of two band gap energies corresponding to CsPbBr3(2.34 eV) and rutile-TiO2(2.97 eV). Time-resolved photoluminescence decays indicate different charge dynamics when comparing both samples, revealing the interaction of CsPbBr3QDs with the microtube surface and thus confirming the formation of local nano-heterostructures. The voltage–current measurements in the dark show an abrupt decrease in the electrical resistivity of the CsPbBr3/TiO2heterostructure reaching almost 95% when compared with the pristine TiO2microtube. This significant increase in the electrical conductivity is associated with charge transfer from perovskite nanocrystals into the semiconductor microtube, which can be used to fine tune its electronic properties. Besides controlling the electrical conductivity, decoration with semiconducting nanocrystals makes the hollow heterostructure photoluminescent, which can be classified as a multifunctionalization in a single device.

The ability to rationally design and synthesize amphiphilic Janus materials with the selective growth of catalytic species on one side represents an important endeavour towards high-efficiency phase-selective catalysis in heterogeneous reaction. Herein, we report, for the first time, the crafting of smart amphiphilic Janus mesoporous nanosheets (denoted JMNs), selectively decorated with Au nanoparticles (NPs) on the hydrophilic side, for robust and dual-functional interfacial emulsification and catalysis. First, two amphiphilic JMNs are judiciously created (i.e., C18-mSiO2-P4VP composed of mesoporous silica (mSiO2) nanosheets sandwiched by C18and poly(4-vinylpyridine) (P4VP) on opposite sides of the nanosheets; and C18-mSiO2-NH2with C18and NH2on the respective sides). Subsequently, the in situgrowth of Au NPs on the hydrophilic side of the nanosheets yields C18-mSiO2-P4VP@Au and C18-mSiO2-NH2@Au. Notably, these JMNs exhibit pH-dependent catalytic activity in aqueous solution and oil-phase-type-dependent catalytic activity at the emulsion interface. Moreover, both JMNs manifest reversible interfacial emulsification/de-emulsification behaviour. Finally, they also feature excellent recyclability, rendering them promising in heterogeneous catalysis. In principle, given the diversity of functional polymers that can be easily grafted on mSiO2nanosheets, a rich variety of JMNs with other stimuli-responsive characteristics (e.g., temperature-, light-, etc.) may be conveniently engineered. As such, a suite of properties (e.g., optical, catalytic, etc.) of these JMNs, triggered by external stimuli noted above, can be scrutinized.

The key to exploiting perovskite nanocrystals (NCs) for long-term practical use in optoelectronic materials and devices lies in the ability to access stable NCs. Herein, we report the crafting of hairy perovskite NCs with a set of markedly improved stabilities by capitalizing on rationally designed star-like molecular bottlebrush trilobes as nanoreactors. An intriguing star-like molecular bottlebrush trilobe, poly(2-hydroxyethyl methacrylate)-graft-(poly(acrylic acid)-block-partially cross-linked polystyrene (denoted PHEMA-g-(PAA-b-cPS)) is synthesized. Subsequently, it is employed as a polymeric nanoreactor to direct the growth of green-emitting all-inorganic perovskite CsPbBr3NCs intimately and stably tethered by partially cross-linked PS “hairs” (i.e., cPS-capped CsPbBr3NCs). The resulting CsPbBr3NCs exhibit an array of impressive stabilities against UV irradiation, moisture, heat, and water, due to permanently ligated hydrophobic cPS “hairs” on the surface of CsPbBr3NCs as a result of the original covalent bonding between PAA and cPS blocks. More importantly, cPS-capped CsPbBr3NCs manifest outstanding stability in various polar organic solvents. Such greatly improved stability can be attributed to the reduced surface defects enabled by the favorable interaction (i.e., coordination interaction and hydrogen bonding) between CsPbBr3NCs and polar solvents, which dominates over their dissolution by polar solvents. Such exceptional stabilities impart the use of cPS-capped CsPbBr3NCs as a selective probe for tracing the presence of Cl–/I–in polar organic solvents. The amphiphilic nonlinear block copolymer nanoreactor strategy can afford easy access to stable perovskite NCs of interest with controlled compositions and surface chemistry. They may find applications in solar cells, LEDs, photodetectors, lasers, bioimaging, biosensors, etc.

The ability to rationally design binder-free electrode materials that possess interconnected nanostructures is highly desirable for lithium-ion batteries (LIBs) with long cycling and excellent rate performances. Such electrode containing pores between nanostructures imparts large-area contact with electrolyte, improved electrical conductivity with current collector, and good structural stability and mechanical integrity. Herein, we report, for the first time, outstanding cycling stability and rate performance of CuO electrode in LIBs. CuO nano-labyrinths (NLs) composed of densely interlaced nanowalls on Cu foil are crafted via a facile solution-based etching process. It is notable that macroscopic and mesoscopic pores are found to ubiquitously present among the adjacent CuO nanowalls and within the nanowall, respectively (i.e., forming hierarchically porous CuO NLs). Intriguingly, CuO NLs anodes yield an ultralong cycling stability, that is, a specific capacity of 320 mA h g−1after 800 cycles without the capacity fading at high current density of 1 A g−1, and an outstanding high-rate performance (up to 30 C). This is a direct consequence of unique synergistic effects of hierarchical pores and interlaced nanostructures. Moreover, a further enhancement of reversible capacity is achieved by deposition Si thin film on the surface of CuO NLs. Such interlaced nanowall-containing structures with hierarchical pores represent an important type of architectures that underpin the development of electrode materials for long cycle-life energy storage devices.

It is known that contact-electrification (or triboelectrification) usually occurs between two different materials, which could be explained by several models for different materials systems (Adv. Mater. 2018, 30, 1706790; Adv. Mater. 2018, 30, 1803968). But contact between two pieces of the chemically same material could also result in electrostatic charges, although the charge density is rather low, which is hard to understand from a physics point of view. In this paper, by preparing a contact-separation mode triboelectric nanogenerator using two pieces of an identical material, the direction of charge transfer during contact-electrification is studied regarding its dependence on curvatures of the sample surfaces. For materials such as polytetrafluoroethylene, fluorinated ethylene propylene, Kapton, polyester, and nylon, the positive curvature surfaces are net negatively charged, while the negative curvature surfaces tend to be net positively charged. Further verification of the above-mentioned trends was obtained under vacuum (∼1 Pa) and higher temperature (≤358 K) conditions. Based on the received data acquired for gentle contacting cases, we propose a curvature-dependent charge transfer model by introducing curvature-induced energy shifts of the surface states. However, this model is subject to be revised if the mutual contact mode turns into a sliding mode or more complicated hard-pressed contact mode, in which a rigorous contact between the two pieces of the same material could result in nanoscale damage/fracture and possible species transfer. Our study provides a primitive step toward understanding the basics of contact-electrification.

Graphene, a two-dimensional (2D) carbon nanomaterial, has received great attention owing to its advantageous characteristics, including superior electrical, chemical and physical properties. In particular, exfoliation of graphite with strong oxidants has been explored to prepare a suspension of individual 2D graphene oxide (GO) nanosheets dispersed in various types of solvents. This colloidal suspension can readily be employed in a wide range of promising potential applications. However, one major challenge is to assemble such individual nanosheets on defined areas of surfaces forming specific structures. Here, we developed a simple and robust one-step strategy to create highly regular ordered nanostructures composed of chemically reduced graphene oxide (rGO) nanosheet building blocks on SiO2/Si or glass substrates over large areas. An aqueous suspension of rGO nanosheets dispersed in a volatile solvent was subjected to a confined geometry to induce a spontaneous formation of rGO patterned arrays with unprecedented regularity by utilizing both a controlled coffee ring effect and consecutive stick-slip motions of rGO solutions during the drying process. As a result, the generation of ultrathin nanotextured films in the form of micropatterns (i.e., concentric gradient rGO coffee rings) was effectively tailored. As a biological approach, to fully utilize patterned rGO associated with the nanoscale surface topography, we used these patterned rGO arrays as a biomimetic in vitroarchitecture to study interfacial interactions of living cells such as fibroblasts, myoblasts, and neuronal cells. The observed results show that the patterned rGO arrays can be used as manipulated cellular responsive templates to form living cell assemblies and related patterns that are useful for regenerative tissue engineering.

Understanding the activity origins of electrocatalysts for the triiodide (I3-) reduction is highly desirable in dye-sensitized solar cells (DSSCs). Herein, we report a robust strategy to craft nitrogen-doped carbon nanowires (NCWs) through combining oxidation polymerization from p-phenylenediamine with carbonization process. Owing to the abundant edges of the graphite microcrystals embedded in the NCWs and the incorporated N species, the NCWs synthesized at 700 °C exhibit a superior response to the I3-reduction in DSSCs with a high power conversion efficiency of 8.90%, outperforming the Pt reference (8.09%), and a high stability is also manifested. Theoretical calculations reveal that, of various doped N species within NCWs, the quaternary N species can significantly decrease the ionization energy and modulate the spin density distribution of carbon frameworks, thus promoting the electron transfer from the external circuit to the electrolyte. Natural population analysis further reveals that the active centers within the NCWs for the I3-reduction are those positively charged carbon atoms adjacent to the quaternary N. As such, this work will pave an avenue for rational design and engineering of inexpensive yet high-efficiency carbon electrocatalysts for the advanced energy applications.

Semiconducting organic–inorganic nanocomposites comprising conjugated polymers (CPs) and semiconducting nanocrystals (NCs) represent an important class of functional materials. The ability to organize CPs and NCs into self-assembled nanostructures in close proximity may enable efficient charge or energy transfer between them for use in flexible electronics, light-emitting displays, and photovoltaics. Herein we report the crafting of one-dimensional (1D) functional nanocomposites composed of all-conjugated diblock copolymers and CdSe nanorods (NRs) via two consecutive self-assembly processes, namely, self-assembly of poly(3-hexylselenophene)-block-poly(3-butylselenophene) (denoted P3HS-b-P3BS) diblock copolymers into nanofibers, followed by self-assembly of P3HS-b-P3BS nanofibers and CdSe NRs to yield P3HS-b-P3BS–CdSe NR nanocomposites. Notably, P3HS-b-P3BS diblock copolymers are first rationally designed and synthesized, exhibiting a narrow optical bandgap and forming nanofibers due to strong interchain π–π stacking (i.e., first self-assembly). Subsequently, the addition of CdSe NRs into P3HS-b-P3BS nanofiber solution results in the formation of 1D P3HS-b-P3BS–CdSe NR nanocomposites driven by the van der Waals interaction between aliphatic ligands on the surface of CdSe NRs and the hexyl side chains of P3HS-b-P3BS and the coordination interaction between the selenium of P3HS and the surface of CdSe NRs (i.e., second self-assembly). Quite intriguingly, an integrated Monte Carlo simulation and experimental study reveals that CdSe NRs are aligned parallel to the long axis of P3HS-b-P3BS nanofibers in an end-to-end mode at low concentration of CdSe. When high concentration of CdSe NRs is introduced, coexistence of the side-by-side and layer-by-layer assemblies of CdSe NRs along P3HS-b-P3BS nanofibers is yielded. Photoluminescence quenching of CdSe NRs is observed, suggesting an efficient charge transfer between CdSe and P3HS-b-P3BS. Such self-assembled conjugated diblock copolymer–quantum rod nanocomposites may find applications in optics, optoelectronics, and sensors.

We report a simple, robust, and inexpensive strategy to enable all-inorganic CsPbX3perovskite nanocrystals (NCs) with a set of markedly improved stabilities, that is, water stability, compositional stability, phase stability, and phase segregation stability via impregnating them in solid organic salt matrices (i.e., metal stearate; MSt). In addition to acting as matrices, MSt also functions as the ligand bound to the surface of CsPbX3NCs, thereby eliminating the potential damage of NCs commonly encountered during purification as in copious past work. Quite intriguingly, the resulting CsPbX3–MSt nanocomposites display an outstanding suite of stabilities. First, they retain high emission in the presence of water because of the insolubility of MSt in water, signifying their excellent water stability. Second, anion exchange between CsPbBr3–MSt and CsPbI3–MSt nanocomposites is greatly suppressed. This can be ascribed to the efficient coating of MSt, thus effectively isolating the contact between CsPbBr3and CsPbI3NCs, reflecting notable compositional stability. Third, remarkably, after being impregnated by MSt, the resulting CsPbI3–MSt nanocomposites sustain the cubic phase of CsPbI3and high emission, manifesting the strikingly improved phase stability. Finally, phase segregation of CsPbBr1.5I1.5NCs is arrested via the MSt encapsulation (i.e., no formation of the respective CsPbBr3and CsPbI3), thus rendering pure and stable photoluminescence (i.e., demonstration of phase segregation stability). Notably, when assembled into typical white light-emitting diode architecture, CsPbBr1.5I1.5–MSt nanocomposites exhibit appealing performance, including a high color rendering index (Ra) and a low color temperature (Tc). As such, the judicious encapsulation of perovskite NCs into organic salts represents a facile and robust strategy for creating high-quality solid-state luminophores for use in optoelectronic devices.

The ability to facilitate charge transfer in electron transport layer (ETL) is highly desirable for high-efficiency perovskite solar cells (PSCs). Herein, we report the judicious design of ETL composed of edge-enriched graphene nanoribbons (GNRs) and TiO2nanocrystals to enable markedly improved charge carrier conductivity and, more importantly, well-aligned energy levels at the perovskite/ETL/fluorine doped tin oxide (FTO) interfaces for imparting the cascade charge transfer, thereby leading to improved power conversion efficiency (PCE) of PSCs. The investigation into the influence of the GNR content within ETL on device performance demonstrated that excessive GNRs are detrimental for charge transfer as they block the contact between TiO2and perovskite. In contrast to devices using pure TiO2as ETL with a PCE of 15.87%, the PSCs employing GNRs-incorporated ETL display the improved photovoltaic performance with a highest PCE of 17.69%, a steady-state efficiency output of 17.05%, and a reduced current-voltage hysteresis. Subsequently, a systematic photo-carrier dynamics study revealed that the performance enhancement was a direct consequence of (a) the promoted fill factor and open circuit voltage due to the improved electron diffusion coefficient and the longer charge recombination time, (b) the increased charge collection efficiency owing to the cascade charge transfer from TiO2to GNRs to FTO electrode, resulting in a higher external quantum efficiency and thus a larger short circuit current density and (c) the suppressed current-voltage hysteresis ascribed to the increased charge transfer noted above. Finally, a markedly improved long-term stability was manifested. As such, the rational incorporation of edge-enriched GNRs represents a feasible and robust strategy to formulate promising ETLs for high-efficiency and stable PSCs.

Despite recent vigorous progress in synthesis of monofunctional electrocatalysts for hydrogen evolution reaction (HER) or oxygen evolution reaction (OER), it remains challenging to develop bifunctional electrocatalysts for efficient overall water splitting. Herein, we report the crafting of MoC2-doped NiFe alloy nanoparticles (NPs) encapsulated within a-few-layer-thick N-doped graphene (denoted NG-NiFe@MoC2) via one-step calcination of hybrid precursors containing polymer-encapsulating binary Prussian blue analogues NPs and Mo6+cations. The resulting NG-NiFe@MoC2nanohybrids were exploited as electrocatalysts and exhibited excellent performance on either HER or OER separately as a direct consequence of the synergistic effects of unique compositions (i.e., MoC2dopants and NiFe alloy NPs; both exerted profound influence on HER and OER) and advantageous architecture (i.e., a-few-layer-thick N-doped graphene encapsulating shell). Remarkably, an alkaline electrolyte capitalizing on NG-NiFe@MoC2nanohybrids as bifunctional electrocatalysts achieved overall water-splitting (i.e., concurrent HER and OER) current density of 10 mA cm−2at a low potential of 1.53 V over a period of 10-h operation, outperforming the precious Pt/C//RuO2counterpart.

Transition metal oxide catalysts with high oxygen reduction activity and durability are highly desirable for use in fuel cells and metal-air batteries. Herein we report, for the first time, the oxygen reduction activity of hollow porous spinel AB2O4microspheres, where A = Zn2+and B = Mn3+and/or Co3+(i.e., ZnMnxCo2−xO4). Among them, ZnMnCoO4(x = 1) microspheres exhibit the best oxygen reduction activity with a half-wave-potential only 50 mV lower than that of the Pt/C counterpart and an excellent durability in the alkaline solution. Importantly, the electronic transition of Co3+ions from low-spin state in commercial Co3O4catalyst to a mixed high-spin and low-spin state in ZnMnCoO4catalyst was found to weaken the Co3+-OH bond and facilitate the O2−/OH−displacement. The density functional theory calculation substantiated that ZnMnCoO4displayed a more favorable binding energy with O2and oxygenated species, thereby enabling the fast reaction kinetics in the oxygen reduction reaction process.

Hierarchically arranged stripes of photoswitchable liquid crystal polymers (LCPs) containing azobenzene moieties were conveniently crafted via a flow-enabled self-assembly (FESA). Interestingly, by subjecting a drop of LCP solution to dry in a restricted geometry comprising two nearly parallel plates with a stationary upper plate and a movable lower plate that programmably traveled in a “stop-and-move” manner during the FESA process, photoswitchable LCP stripes were yielded, displaying two modes of deposition, namely, periodic primary stripes of large dimensions and regularly spaced secondary stripes of small dimensions situated between adjacent primary stripes (i.e., forming hierarchical LCP stripes). Notably, these hierarchical azobenzene moieties-containing stripes demonstrated sequential photoinduced reversible phase transition (i.e., photoswitching) due to the thickness difference between primary and secondary stripes. A UV light-induced expansion effect was observed on the LCP stripes. Clearly, such rapid creation of hierarchical stripes by FESA represents a robust means of organizing polymers, nanoparticles, colloids, DNA, etc. into complex yet ordered patterns over a large area in a simple and controllable manner for potential use in surface relief grating, photoactuators, photoswitchable devices, antifake labels, etc.

Melt diffusion followed by vapor deposition is judiciously combined with atomic layer deposition (ALD) to construct Al2O3–coated (Se/porous N-doped carbon nanofibers)@Se composite (denoted SC@Se-Al2O3) materials for sodium-selenium (Na-Se) batteries. High mass loading, ultrastable and free-standing carbon-selenium cathode is conveniently achieved by tailoring both the Se content and the thickness of deposited Al2O3layer. Importantly, in contrast to only 176 mAh g−1of the electrode without Al2O3deposition after 660 cycles, the composite with a Se content of 67wt% and a 3-nm Al2O3thickness retains a reversible capacity of 503 mAh g−1after 1000 cycles with no capacity fading at 0.5Ag−1. These findings clearly suggest that ALD strategy provides a viable, controllable and effective means of tuning the electrode performance towards high mass loading of active materials and long cycle life of the resulting battery for energy storage applications.

The rational design and facile synthesis of cost-effective and high-performance carbon-based catalysts for oxygen reduction reaction (ORR) is of great significance but remain challenging. Herein, we report the crafting of a robust Fe,N,P-codoped, ultrafine Fe2P nanocrystals decorated, highly hierarchical porous carbon nanoshells (denoted Fe,N,P-CNSs/Fe2P) via a simple yet robust one-step synergetic phosphorization and pyrolysis approach for highly-efficient ORR. Specifically, well-defined polypyrrole-co-polyaniline hollow nanospheres with a shell thickness of ≈ 43 nm (PPy-co-PANI-HNs) are first elaborately synthesized via a facile soft-templating (Triton X-100 micelles) copolymerization of pyrrole and aniline monomers. Subsequent one-step synergetic phosphorization and pyrolysis of PPy-co-PANI-HNs pre-impregnated with NaH2PO2·H2O and FeCl3(H2PO2-,Fe3+@PPy-co-PANI-HNs) yields Fe,N,P-CNSs/Fe2P with a well-crafted ultrathin nanoshell (shell thickness of ≈13 nm) architecture containing abundant hierarchical porosity. Remarkably, an alkaline electrolyte capitalizing on the resulting Fe,N,P-CNSs/Fe2P manifests excellent ORR performance with the half-wave and onset potentials (E1/2of 0.854 V and Eonsetof 0.955 V) comparable to Pt/C, diffusion limited current density (JLof −5.98 mA cm−2) higher than Pt/C, and long-time durability and methanol resistance better than Pt/C, demonstrating great potential as air cathode in zinc-air batteries (maximum power density of 170 mW cm−2and specific capacity of 824.5 mA h g−1). Combined experimental and theoretical studies reveal that the impressive ORR performance of Fe,N,P-CNSs/Fe2P originates from simultaneous compositional (i.e., Fe,N,P-codoping and ultrafine Fe2P nanocrystals decorating) and structural (i.e., hierarchically porous ultrathin nanoshell architecture) tailoring enabled by the judicious one-step synergetic phosphorization and pyrolysis.

This work demonstrates a facile and versatile method for generating low scattering cross-linked quantum dot (QD)–polymer composite films and patterned highly emissive structures with ultrahigh QD loading, minimal phase separation, and tunable mechanical properties. Uniform QD–polymer films are fabricated using thiol–ene chemistry, in which cross-linked polymer networks are rapidly produced in ambient conditions via fast UV polymerization in bulk to suppress QD aggregation. UV-controlled thiol–ene chemistry limits phase separation through producing highly QD loaded cross-linked composites with loadings above majority of those reported in the literature (<1%) and approaching 30%. As the QD loading is increased, the thiol and ene conversion decreases, resulting in nanocomposites with widely variable and tailorable mechanical properties as a function of UV irradiation time with an elastic modulus decreasing to 1 GPa being characteristic of reinforced elastomeric materials, in contrast to usually observed stiff and brittle materials under these loading conditions. Furthermore, we demonstrate that the thiol–ene chemistry is compatible with soft-imprint lithography, making it possible to pattern highly loaded QD films while preserving the optical properties essential for high gain and low optical loss devices. The versatility of thiol–ene chemistry to produce high-dense QD–polymer films potentially makes it an important technique for polymer-based elastomeric optical metamaterials, where efficient light propagation is critical, like peculiar waveguides, sensors, and optical gain films.

We present novel photopatterning approaches based on near-field and far-field interference lithography techniques that yield highly uniform high-resolution large-area face-profile and edge-profile photopatterns. The near-field interference methods utilize a phase-shift mask while the far-field method uses two-beam interference. These interference-based techniques yield photopatterns with minimum feature sizes near 500 nm, which matches the current resolution of photopatterning. Furthermore, these interference techniques drastically increase the patternable area (up to cm2) and the throughput (increases of up to 3 orders of magnitude) while maintaining pattern uniformity. Furthermore, these strategies use easy-to-handle reusable photomasks or no masks at all and address the major constraints associated with obtaining high resolution without compromising throughput that have often limited the applicability of traditional photopatterning. Finally, all approaches can be applied multiple times on the same film area to yield ultradense multilevel intensity contrast photopatterns that are very difficult to obtain using traditional strategies. These interference-based exposure techniques represent a paradigm shift in the field of photopatterning and will be valuable for applications that require uniform high-resolution patterns over large areas, such as photosensors, anticounterfeiting labels, and virtual displays.

Despite stunning progress in single-atom catalysis (SAC), it remains a grand challenge to yield a high loading of single atoms (SAs) anchored on substrates. Herein, we report a one-step laser-planting strategy to craft SAs of interest under an atmospheric temperature and pressure on various substrates including carbon, metals, and oxides. Laser pulses render concurrent creation of defects on the substrate and decomposition of precursors into monolithic metal SAs, which are immobilized on the as-produced defects via electronic interactions. Laser planting enables a high defect density, leading to a record-high loading of SAs of 41.8 wt %. Our strategy can also synthesize high-entropy SAs (HESAs) with the coexistence of multiple metal SAs, regardless of their distinct characteristics. An integrated experimental and theoretical study reveals that superior catalytic activity can be achieved when the distribution of metal atom content in HESAs resembles the distribution of their catalytic performance in a volcano plot of electrocatalysis. The noble-metal mass activity for a hydrogen evolution reaction within HESAs is 11-fold over that of commercial Pt/C. The laser-planting strategy is robust, opening up a simple and general route to attaining an array of low-cost, high-density SAs on diverse substrates under ambient conditions for electrochemical energy conversion.

The ability to substitute oxygen evolution reaction (OER) in water splitting with ammonia oxidation reaction (AOR) represents an important endeavor in producing high-purity hydrogen with the lowered energy consumption. Due to the reduced overpotential of AOR over OER and preventing the hydrogen and oxygen mixing and thus possible explosion. Herein, we report the substitution of slow-kinetics OER with AOR to effectively boost hydrogen evolution reaction (HER) of wastewater electrolysis, thereby rendering energy saving as well as decontamination of ammonia (NH3) in wastewater. Three-dimensional CoS@NiCu electrodeposited on Ni foam is employed as self-supporting bifunctional electrocatalysts for both AOR and HER. The XPS and in-situRaman studies reveal the generation of electrocatalytically active cobalt oxyhydroxide (CoOOH) on CoS@NiCu during the course of AOR. Interestingly, the density functional theory (DFT) calculation unveils that NH3preferentially adsorbing on the surface of electrocatalyst prolongs the Co-S bond length, thus promoting the bond cleavage and accelerating the formation of active CoOOH species. Moreover, the rate-determining step of AOR according to the Gerischer-Mauerer (G-M) mechanism only has a 1.79eV energy barrier to overcome. The electrochemical impedance spectroscopy investigation suggests that the AOR enables an enhanced interfacial charge transfer. As such, the hydrogen evolution rate of the AOR-HER system reaches 41.9 μmol h-1, representing 3.2-fold increase in hydrogen production over the conventional OER-HER water splitting. This study highlights a promising perspective of integrating AOR with HER to synergize efficient hydrogen production.

The ability to enhance the specific capacity of Li4Ti5O12(LTO) is of practical significance and offers the opportunity to increase the energy density of a full LTO-based battery. Widening the discharge cutoff voltage to 0 V is an effective way to increase the capacity of LTO at low current density. However, whether the specific capacity of LTO at large current rates can be enhanced remains largely unknown. Herein, intriguingly, we found that, when cycled down to 0 V (i.e., from 1.0−2.5 to 0−25 V), LTO exhibited greatly enhanced specific capacity at low rates (<5 C), while it showed a rapid capacity fading and a greatly increased charge/discharge potential gap at high rates (>10 C). The decreased lithium-ion diffusion caused by extra lithium-ion intercalation together with increased internal impedance significantly enhances the polarization and reduces the electrochemical reaction kinetics, which, in turn, hinders the lithiation reaction from LTO to Li7Ti5O12and further to Li9Ti5O12.

The ability to suppress the dissolution of lithium polysulfides in liquid electrolyte (LE) is emerging and scientifically challenging, representing an important endeavor toward successful commercialization of lithium–sulfur (Li–S) batteries. In this context, a common and effective strategy to address this challenge is to replace the LE with a gel polymer electrolyte (GPE). However, the limited ionic conductivity of state-of-the-art GPEs and poor electrode/GPE interfaces greatly restrict their implementation. Herein, we report, for the first time, a facile in-situ synthesis of pentaerythritol tetraacrylate (PETEA)-based GPE with an extremely high ionic conductivity (1.13×10−2Scm−1). Quite intriguingly, even interfaced with a bare sulfur cathode, this GPE rendered the resulting polymer Li–S battery with a low electrode/GPE interfacial resistance, high rate capacity (601.2mAhg−1at 1C) and improved capacity retention (81.9% after 400 cycles at 0.5C). These remarkable performances can be ascribed to the immobilization of soluble polysulfides imparted by PETEA-based GPE and the construction of a robust integrated GPE/electrode interface. Notably, due to the tight adhesion between the PETEA-based GPE and electrodes, a high-performance flexible polymer Li–S battery was successfully crafted. This work therefore opens up a convenient, low-cost and effective way to substantially enhance the capability of Li–S batteries, a key step toward capitalizing on GPE for high-performance Li–S batteries.

The ability to synthesizing monodisperse Li4Ti5O12(LTO) nanospheres is the key to reducing the irreversible capacity of LTO materials, and thus improving their power performance. However, it remains a grand challenge to achieve uniform precursors of LTO nanospheres and maintain their spherical structures after annealing. Herein, we develop a robust strategy for the synthesis of monodisperse LTO nanospheres with an average diameter of 120nm via the use of titanium nitride (TiN) as a titanium source for lithium ion batteries (LIBs). The precursors composed of uniform TiO2/Li+nanospheres were formed in a stable alkaline environment during the course of heating of the solution of peroxo-titanium complex as a result of the dissolution of TiN, while TiO2/Li+microspheres were easily yielded with the decrease in pH value of the precursor solution. The OH−anion was found to effectively retard the hydrolysis of peroxo-titanium complex as well as the aggregation of TiO2/Li+nanoparticles. Intriguingly, a uniform polyvinyl pyrrolidone (PVP) layer formed in-situ on the surface of TiO2/Li+nanospheres rendered LTO to retain the monodisperse spherical morphology after annealing. Notably, the as-prepared monodisperse LTO nanospheres comprised of the interconnected LTO nanograins with an average size of ~15nm uniformly coated by a carbon layer derived from the carbonization of PVP exhibited a high tap density (1.1gcm−3) and an outstanding rate-cycling capability. The charge specific capacities at 1, 10, 50 and 80C were 159.5, 151.1, 128.8 and 108.9mAh g−1, respectively. More importantly, the capacity retention after 500 cycles at 10C was as high as 92.6%. This work opens up an avenue to craft the uniform precursors of LTO and thus monodisperse LTO nanospheres that possess superior rate performance with high volumetric energy densities and long-term cyclic stability.

The ability to create a synergistic effect of nanostructure engineering and its hybridization with conductive carbonaceous material is highly desirable for attaining high-performance lithium ion batteries (LIBs). Herein, we judiciously crafted ZnFe2O4/carbon nanocomposites composed of ZnFe2O4nanoparticles with an average size of 16 ± 5 nm encapsulated within the continuous carbon network as anode materials for LIBs. Such intriguing nanocomposites were yielded in situ viathe pyrolysis-induced carbonization of polystyrene@poly(acrylic acid) (PS@PAA) core@shell nanospheres in conjunction with the formation of ZnFe2O4nanoparticles through the thermal decomposition of ZnFe2O4precursors incorporated within the PS@PAA nanospheres. By systematically varying the ZnFe2O4content in the ZnFe2O4/carbon nanocomposites, the nanocomposite containing 79.3 wt % ZnFe2O4was found to exhibit an excellent rate performance with high capacities of 1238, 1198, 1136, 1052, 926, and 521 mAh g–1at specific currents of 100, 200, 500, 1000, 2000, and 5000 mA g–1, respectively. Moreover, cycling performance of the ZnFe2O4/carbon nanocomposite with 79.3 wt % ZnFe2O4at specific currents of 200 mA g–1delivered an outstanding prolonged cycling stability for several hundred cycles.

The ability to render the cocrystallization over microphase separation in all-conjugated block copolymers represents an important endeavor towards achieving enhanced charge transport. This, however, remains a grand challenge, particularly in all-conjugated triblock copolymers. Herein, we report the unravelling of the dependence of cocrystallization in all-conjugated triblock copolymers on a set of internal structural parameters, and more importantly, the scrutiny of the correlation of their unique cocrystalline structures to charge transport properties for organic field-effect transistors (OFETs). Specifically, a series of poly(3-butylthiophene)-block-poly(3-alkylthiophene)-block-poly(3-hexylselenophene) triblock copolymers (denoted P3BT-b-P3AT-b-P3HS) are meticulously designed and synthesized. Intriguingly, a shorter alkyl side chain length and a shorter main chain length of the central P3AT, as well as a stronger cocrystallization ability of the two outer blocks (P3BT and P3HS), are found to favor the cocrystallization of the three dissimilar blocks in P3BT-b-P3AT-b-P3HS. Notably, the charge transport properties of P3BT-b-P3AT-b-P3HS correlate strongly to their various crystalline structures, thereby imparting their utility for high-performance OFETs. This study highlights the robustness of meticulous molecular engineering of all-conjugated multiblock copolymers in tailoring their cocrystallization behavior and in turn charge transport characteristics that underpins their advances in optoelectronic materials and devices.

Instability of perovskite nanocrystals driven by their ionic crystal characteristic poses a grand challenge for long-term practical applications in optoelectronic materials and devices. Herein, we report the crafting of amphiphilic perovskite nanocrystal composites (APNCCs) with a set of markedly improved stabilities via capitalizing on polymer-grafted silica nanosheets as nanoreactors in conjunction with surface ligand engineering. First, SiO2nanosheets grafted with poly(acrylic acid)-block-polystyrene (denoted SiO2@PAA-b-PS) are rationally designed and exploited as nanoreactors to form SiO2@CsPbBr3@PS. Subsequent passivation with small-molecule ligands (L) yields highly emissive SiO2@CsPbBr3@ (PS/L) APNCCs with an array of outstanding stabilities against UV, heat, water, long-term storage, and various polar organic solvents. Remarkably, our strategy integrating polymer-grafted SiO2nanosheet nanoreactor with surface ligand engineering is general and viable. A diversity of stable APNCCs can be readily created. Finally, white light-emitting diode (WLED) with wide color gamut and excellent stability composed of green-emitting SiO2@CsPbBr3@ (PS/L) APNCCs is demonstrated. This work highlights the robustness of the synergy of judiciously-designed nanoreactor and surface ligand engineering to produce highly emissive, ultrastable perovskite nanocrystals shielded with soft and hard materials (i.e., possessing a Janus surface chemistry).

Sn materials offer high theoretical capacities in lithium ion batteries, but they must have good cycling stability and high rate-capability in order to be commercialized. Complex and costly material treatments of Sn have been effective in reducing capacity fade, but conventionally produced bare Sn is desired for reducing cost. One simple method is to form a high-quality solid electrolyte interphase (SEI) on Sn particles with low resistance and high passivation. Fluoroethylene carbonate (FEC) added to the electrolyte forms a protective and less-resistant SEI on Sn particles during the in-situ electrochemical SEI formation cycle. FEC is a good oxidizing agent that removes highly oxidized carbon compounds and makes a SEI thinner during an oxidation process (delithiation) of SEI formation cycle. The high-quality SEI greatly improves the rate-capability and capacity of nano-sized bare Sn electrodes without any treatments: minimal capacity fade (0.014% cycle−1) at 320mAhg−1(1.3C) for 150 cycles. The mitigating effect of FEC on capacity fade is not seen with electrodes fabricated from micro-scale (0.1~0.2μm) Sn. The long lithium-ion diffusion path makes these micro-sized materials susceptible to decrepitation during repeated volume changes.

Hierarchically assembled amphiphilic diblock copolymer micelles were exquisitely crafted over large areas by capitalizing on two concurrent self-assembling processes at different length scales, namely, the periodic threads composed of a monolayer or a bilayer of diblock copolymer micelles precisely positioned by flow-enabled self-assembly (FESA) on the microscopic scale and the self-assembly of amphiphilic diblock copolymer micelles into ordered arrays within an individual thread on the nanometer scale. A minimum spacing between two adjacent threads λminwas observed. A model was proposed to rationalize the relationship between the thread width and λmin. Such FESA of diblock copolymer micelles is remarkably controllable and easy to implement. It opens up possibilities for lithography-freepositioning and patterning of diblock copolymer micelles for various applications in template fabrication of periodic inorganic nanostructures, nanoelectronics, optoelectronics, magnetic devices, and biotechnology.

Peachlike rutile TiO2microsphere films were successfully produced on transparent conducting fluorine-doped tin oxide substrate via a facile, one-pot chemical bath route at low temperature (T= 80–85 °C) by introducing polyethylene glycol (PEG) as steric dispersant. The formation of TiO2microspheres composed of nanoneedles was attributed to the acidic medium for the growth of 1D needle-shaped building blocks where the steric interaction of PEG reduced the aggregation of TiO2nanoneedles and the Ostwald ripening process. Dye-sensitized solar cells (DSSCs) assembled by employing these complex rutile TiO2microspheres as photoanodes exhibited a light-to-electricity conversion efficiency of 2.55%. It was further improved to a considerably high efficiency of 5.25% upon a series of post-treatments (i.e., calcination, TiCl4treatment, and O2plasma exposure) as a direct consequence of the well-crystallized TiO2for fast electron transport, the enhanced capacity of dye loading, the effective light scattering, and trapping from microstructures.

The ability to tune polymorphs of conjugated polymers affords a robust platform for investigating the processing–structure–property relationship. However, simple and generalizable routes to polymorphs have yet to be realized. Herein, we report a viable meniscus-assisted solution-shearing (MASS) strategy to effectively modulate polymorphs (i.e., polymorphs I and II) of poly(3-butylthiophene) (P3BT) and scrutinize the correlation between the two different polymorphs and charge transport characteristics. Specifically, polymorph II exists solely in drop-cast P3BT films. Intriguingly, confined shearing of P3BT renders efficient transformation of polymorph II to I. The kinetics of polymorph transformation associated with the changes in molecular packing and thus photophysical properties are elucidated. The resulting organic field-effect transistors reveal a strong correlation of device performance to attained polymorphs and crystal orientations of P3BT. Such polymorph transformation viathe convenient MASS technique can be readily extended to other conjugated polymers of interest. This study highlights the robustness of MASS in regulating polymorphs of conjugated polymers to interrogate their interdependence of processing, structure, and property for a wide range of optoelectronic applications.

SiO-based materials represent a promising class of anodes for lithium-ion batteries (LIBs), with a high theoretical capacity and appropriate and safe Li-insertion potential. However, SiO experiences a large volume change during the electrochemical reaction, low Li diffusivity, and low electron conductivity, resulting in degradation and low rate capability for LIBs. Here, we report on the rapid crafting of SiO–Sn2Fe@C composites via a one-step plasma milling process, leading to an alloy of Sn and Fe and in turn refining SiO and Sn2Fe into nanoparticles that are well dispersed in a nanosized, few-layer graphene matrix. The Sn and Fe nanoparticles generated during the first Li-insertion process form a stable network to improve Li diffusivity and electron conductivity. As an anode material, the SiO–Sn2Fe@C composite manifests high reversible capacities, superior cycling stability, and excellent rate capability. The capacity retention is found to be as high as 95% and 84% at the 100th and 300th cycles under 0.3 ​C. During rate capability testing at 3, 6, and 11 ​C, the capacity retentions are 71%, 60%, and 50%, respectively. This study highlights that this simple, one-step plasma milling strategy can further improve SiO-based anode materials for high-performance LIBs.

In stark contrast to conventional organic ligand-capped counterparts, the ability to create stable metal halide perovskite nanocrystals strongly tethered with conjugated polymers (CPs) represents an important endeavor toward tailoring charge carrier dynamics at their interface that critically underpins applications of this unique class of all semiconducting, organic–inorganic nanomaterials for optoelectronics. This, however, has yet to be largely explored. Herein, we report, for the first time, the unraveling of efficient charge separation at judiciously designed CP/perovskite quantum dot (QD) interface for photoinduced atom transfer radical polymerization (p-ATRP). Such scrutiny is rendered by in situcrafting an array of monodisperse, highly stable, CP-ligated perovskite QDs with precisely controlled dimensions of each constituent via capitalizing on unimolecular, amphiphilic starlike block copolymers as nanoreactors. The intimate and permanent surface tethering of CPs imparts remarkable thermal, photo, and polar solvent stabilities of CP-ligated perovskite QDs. More importantly, they manifest efficient interfacial charge separation with a profound dependence on the length of ligated CPs and the size of perovskite QDs. The outstanding structural stabilities and charge separation characteristic enable CP-ligated perovskite QDs as robust photocatalysts for p-ATRP of a wide selection of monomers with stable and controllable reaction kinetics, also depending crucially on the length of CPs and the size of perovskite QDs. In principle, an exciting variety of CP-ligated, uniform perovskite QDs with virtually unlimited material choice of both markedly improved stabilities and tunable electronic band alignments can be readily accessed by exploiting the amphiphilic starlike block copolymer nanoreactor strategy for use in photodetectors, sensors, and LEDs, among other areas.

Large-scale highly ordered microchannels were spontaneously and rapidly created by simply drying the colloidal nanoparticle suspension on a rigid substrate. Interestingly, free evaporation of colloidal suspension yielded radially aligned microchannels, while constrained evaporation that was rendered by the use of confined geometries composed of either two nearly parallel plates or a slide placed perpendicular to a rigid substrate imparted the formation of periodic arrays of parallel microchannels in a controllable manner. The microchannels were formed as a result of the competition between stress relaxation due to crack opening that ruptured the film and stress increase due to the loss of solvent. Quite intriguingly, these patterned microchannels can be exploited as templates to craft well-ordered metallic stripes. This facile and scalable approach may offer a new paradigm of producing microscopic patterns over large areas with unprecedented regularity at low cost that can serve as scaffolds for use in microelectronics and microfluidic-based biochips, among other areas.