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Exploring heterostructured photocatalysts for the photocatalytic hydrogenation reaction with water as a proton source and investigating the corresponding intrinsic step-by-step mechanism are of great interest. Here, we develop an S-scheme heterojunction through theoretical design and carried out solvothermal growth of Ce2S3 nanoparticles (NPs) onto electrospun TiO2 nanofibers. The low-dimensional (0D/1D) heterostructure unveils enhanced photocatalytic activity for aniline production by nitrobenzene hydrogenation with water as a proton source. Density functional theory (DFT) calculations indicate the electrons transfer from Ce2S3 to TiO2 upon hybridization due to their Fermi level difference and creates an internal electric field at the interface, driving the separation of the photoexcited charge carriers, which is authenticated by in situ X-ray photoelectron spectroscopy along with femtosecond transient absorption spectroscopy. The step-by-step reaction mechanism of the photocatalytic nitrobenzene hydrogenation to yield aniline is revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy, associated with DFT computational prediction.

Polyelectrolyte complex hydrogel (PECH) is an emerging ion conductive hydrogel made from non-covalent interacted oppositely charged polyelectrolytes in water. However, the construction of PECH with high stretchability, excellent fatigue resistance and self-healability is heavily demanded while remaining a profound challenge. Herein, a hydrogen-bonded network densification strategy is presented for preparing a highly stretchable and deformation-tolerant PECH hydrogel (Fe/CS/PAA), which is composed of an anionic Fe3+-coordinated polyacrylic acid network (Fe-PAA) and cationic Fe3+-coordinated chitosan network (Fe-CS). Benefiting from the formation of dense hydrogen-bonded network between the Fe-PAA and Fe-CS networks activated by salt impregnation, the resultant densified hydrogen-bonded Fe/CS/PAA hydrogel (DHB-Fe/CS/PAA) exhibits large tensile strength (~0.34 MPa), high stretchability (~1370%), low-temperature resistance to −25 °C, and heat-accelerated self-healability. Due to its high stretchability, excellent fatigue resistance and high ionic conductivity, the DHB-Fe/CS/PAA can readily work as a stretchable ionic conductor for skin-inspired ionic strain sensor, displaying high sensitivity in a wide strain range (0.5%–500%), fast response time (<180 ms) and excellent durability for 500 cycles at a 100% strain. Besides, the as-assembled ionic sensor is capable of maintaining high ionic conductivity and mechanical robustness at a sub-zero temperature of −25 °C ascribing to the presence of high-concentration charged functional groups and impregnated salts. As a demonstration, a wearable DHB-Fe/CS/PAA ionic sensor in a resistive mode is assembled, demonstrating high sensitivity, wide response range and excellent cyclability in detecting and distinguishing complex human motions rapidly and in real-time.

Nonvolatile and durable ionogels are emerging and promising stretchable ionic conductors for wearable electronics. However, the construction of reconfigurable and recyclable ionogels with high mechanical robustness, high stretchability, and autonomous healability, while heavily demanded, is very challenging. Here, we present a gradient-responsive cross-linking strategy for preparing a highly stretchable and reconfigurable thermoplastic engineering ionogel (TPEI). The design of both microcrystalline and dense hydrogen bonds in TPEI contributed to the formation of a unique gradient-responsive network. When the TPEI was melt-processed under heating, the microcrystalline network structure was destroyed to form entangled polymer chains, while the high-density hydrogen-bonded network structure was only partially destroyed. The remaining hydrogen-bonded network allowed the TPEI to have a high viscosity for melt processing. When the TPEI was cooled upon melting injection, extrusion, and spinning, the hydrogen-bonded network was rapidly reconstructed in tens of seconds, allowing it to be reconfigured and reshaped, while the microcrystalline network was further reconstructed to improve its mechanical strength and elasticity during subsequent aging. As a result, the TPEI exhibited engineering-hydrogel-level mechanical robustness (>100 kPa), extremely high stretchability (>1000%), wide-temperature tolerance (−20 to 80 °C), and ultrafast self-healability in few seconds. Due to its mechanical adaptability, high ionic conductivity, and reconfigurability, the TPEI was demonstrated to readily work as a self-healable and recyclable stretchable conductor in a wearable skin-inspired sensor for monitoring sophisticated human motions.

Solar-driven semiconductor photocatalysis shows great potential to solve growing energy and environmental crises. Electrospun TiO2 nanofibers (NFs) attract attention due to their chemical stability, nontoxicity, cheapness, large specific surface area, and porous structures. The unique unwoven nanofibrous network facilitates mass transportation compared with bulk materials. Electrospun TiO2 NFs are an ideal substrate for growing secondary nanostructures and constructing heterojunction photocatalysts. The hybrid heterojunctions show enhanced electron–hole separation, improved light absorption, effective activation of reactants, and therefore increased photocatalytic performance. Herein, the electrospinning principle and preparing tactics of electrospun TiO2 fibrous nanostructures including solid, hollow, and core/shell NFs are first described. The construction strategies of electrospun TiO2-based heterojunctions by loading electron or hole cocatalysts and hybridizing secondary semiconductors to engineer catalytic active sites and steer charge carrier separation are outlined. Dopant-induced increased light absorption and enhanced charge transfer of TiO2 NFs are discussed. Further, the applications of electrospun TiO2-based photocatalysts for solar-to-chemical conversion and environmental remediation are elucidated. Finally, the challenges and perspectives for the development of electrospun TiO2-based photocatalysts are underlined, which deepen a systematic understanding of the design and fabrication of more efficient electrospun NFs in the future.

The construction of wearable piezoresistive sensors with high elasticity, large gauge factor, and excellent durability in a harsh high-temperature environment is highly desired yet challenging. Here, a lightweight, superelastic, and fatigue-resistant spongy conductor was fabricated via a sponge-constrained network assembly, during which highly conductive graphene and flame-retardant montmorillonite were alternatively deposited on a three-dimensional melamine scaffold. The as-obtained spongy conductor exhibited a highly deformation-tolerant conductivity up to 80% strain and excellent fatigue resistance of 10,000 compressive cycles at 70% strain. As a result, the spongy conductor can readily work as a piezoresistive sensor and exhibited a high gauge factor value of ∼2.3 in a strain range of 60-80% and excellent durability under 60% strain for 10,000 cycles without sacrificing its piezoresistive performance. Additionally, the piezoresistive sensor showed great thermal stability up to 250 °C for more than 7 days and sufficient flame-retardant performance for at least 20 s. This lightweight, superelastic, and flame-retardant spongy conductor reveals tremendous potential in human motion detection against a harsh high-temperature environment.

Photocatalytic water splitting by heterojunction nanostructures is considered as one of the most favorable pathways for direct solar-to-hydrogen conversion. High-efficiency solar hydrogen production demands an effective separation of charge carriers and their rapid transport to the interface, whereas the charge-transfer pathway in heterojunction photocatalysts is largely elusive. Herein, 2D CdS/2D MXene Schottky heterojunctions are synthesized via a sequence of electrostatic self-assembly process and solvothermal method. The composite photocatalysts exhibit highly efficient and robust hydrogen-evolving performance, far superior than the pristine CdS nanosheets. Furthermore, density functional theory (DFT) calculations are adopted to unveil the charge-transport pathway. It is revealed that an intimate Schottky contact is constructed between CdS and MXene, which further steers the formation of charge flow and expedites the charge migration from CdS to MXene, thus suppressing the recombination of photogenerated charge carriers and boosting the photocatalytic activity for hydrogen evolution.

2D MXenes have received growing attention as highly active and earth-abundant cocatalysts for photocatalytic applications, due to their merits including rich surface chemistry, excellent electrical conductivity, distinct carrier mobility, and good hydrophilicity. In this review, the research progress on MXenes and MXene-based composites in photocatalysis are systematically summarized and discussed. Based on the theoretical and experimental studies, this review focuses mainly on the synthetic methods of MXenes, the roles of MXenes in photocatalysis, the design strategies for MXene-based composites and the state-of-the-art applications of these MXene-based materials in photocatalytic reactions, including water splitting, CO2 reduction, and nitrogen fixation. In addition, this review outlines the surface modification and enhancement mechanism from a material design and synthesis perspective, and highlights the pivotal challenges and potential opportunities in the field of MXene-involved photocatalysis. Therefore, this review is expected to provide a useful reference for the development of MXene-related photocatalytic applications.

The construction of ionic conductive hydrogels with high transparency, excellent mechanical robustness, high toughness, and rapid self-recovery is highly desired yet challenging. Herein, a hydrogen-bonding network densification strategy is presented for preparing a highly stretchable and transparent poly(ionic liquid) hydrogel (PAM-r-MVIC) from the perspective of random copolymerization of 1-methyl-3-(4-vinylbenzyl) imidazolium chloride and acrylamide in water. Ascribing to the formation of a dense hydrogen-bonding network, the resultant PAM-r-MVIC exhibited an intrinsically high stretchability (>1000%) and compressibility (90%), fast self-recovery with high toughness (2950 kJm-3), and excellent fatigue resistance with no deviation for 100 cycles. Dissipative particle dynamics simulations revealed that the orientation of hydrogen bonds along the stretching direction boosted mechanical strength and toughness, which were further proved by the restriction of molecular chain movements ascribing to the formation of a dense hydrogen-bonding network from mean square displacement calculations. Combining with high ionic conductivity over a wide temperature range and autonomous adhesion on various surfaces with tailored adhesive strength, the PAM-r-MVIC can readily work as a highly stretchable and healable ionic conductor for a capacitive/resistive bimodal sensor with self-adhesion, high sensitivity, excellent linearity, and great durability. This study might provide a new path of designing and fabricating ionic conductive hydrogels with high mechanical elasticity, high toughness, and excellent fatigue resilience for skin-inspired ionic sensors in detecting complex human motions.

Organic luminogens have been widely used in optoelectronic devices, bioimaging, and sensing. Conventionally, the synthesis of organic luminogens requires sophisticated, multistep design, reaction, and isolation procedures. Herein, the products of the melt-phase condensation of benzoguanamine (BG; 2,4-diamino-6-phenyl-1,3,5-triazine) at 370-410 °C display interesting reaction-condition-dependent luminescence properties, including photoluminescence (PL) at a variety of wavelengths in the visible spectrum and quantum efficiencies (PLQE) of up to 58% in the powder form. With a simple and straightforward solvent washing procedure, the prominent blue luminescent component BG dimer was obtained in gram scale with >93% purity (96.5% purity after fractional sublimation). The BG dimer exhibited distinct aggregation-induced emission (AIE) properties. PL measurements indicate that the electronically excited state of the BG dimer undergoes efficient intramolecular nonradiative deactivation in room-temperature solution, leading to a significantly reduced PLQE (<0.1%) in solution. These nonradiative processes are substantially inhibited when the dimer existed in the form of crystals, solid aggregates in solution or being fixed in a rigid polymer film, resulting in a significant increase in the PLQE and lifetime. This work not only provided a new understanding for PL properties of self-condensation luminescent products but also represented an unconventional strategy for large-scale preparation of organic luminogens with high purity.

The construction of multiple heteroatom-doped porous carbon with unique nanoarchitectures and abundant heteroatom active sites is promising for reversible oxygen-involving electrocatalysis. However, most of the synthetic methods required the use of templates to construct precisely designed nanostructured carbon. Herein, we introduced an ultrasound-triggered route for the synthesis of a piperazine-containing covalent triazine framework (P-CTF). The ultrasonic energy triggered both the polycondensation of monomers and the assembly into a nanoflower-shaped morphology without utilizing any templates. Subsequent carbonization of P-CTF led to the formation of nitrogen, phosphorus, and fluorine tri-doped porous carbon (NPF@CNFs) with a well-maintained nanoflower morphology. The resultant NPF@CNFs showed high electrocatalytic activity and stability toward bifunctional electrolysis, which was better than the commercial Pt/C and IrO2 electrocatalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively. As a further demonstration, employing NPF@CNFs as air electrode materials resulted in an excellent performance of liquid-state and solid-state Zn-air batteries, showing great potentials of the obtained multiple heteroatom-doped porous carbon electrocatalysts for wearable electronics.

The Ag+ photoreduction by graphitic carbon nitride(g-CN) materials in a high concentration of Ag+ solution is reported, and a series of colorful Ag/g-CN composites is prepared and characterized. The chromatic change correlates to the carbon nitride materials synthesized at different heating temperatures(CNT, where T means heating temperature), taking advantage of the different photocatalytic activities of different CNT. The mechanism beneath this phenomenon is attributed to two factors: the particle size of Ag NPs and the coordinate effect of Ag NPs on CNT sheets. Interestingly, the multicolors of Ag/g-CN composites display only on the CNT materials synthesized from heating melamine-cyanuric acid precursor, but not on the CNT from heating pure melamine. The color of the as-prepared Ag/g-CN composites can endure the corrosion of HNO3 and ethanol, which shows a good chemical stability and may hint its application as chromophores.

Photocatalysis provides a promising protocol for tackling the conjuncture of energy and environment in the light of feasible conversion H2O and CO2 to fuels, such as H2, CO, CH4, CH3OH, by utilizing solar energy. Earth-abundant nickel-based cocatalysts, which can effectively promote photocatalytic efficiency by extending light absorption range, boosting charge separation, providing active sites, and lowering reaction barrier, open up alluring vistas in the arenas of solar-to-fuels conversion. In this review, recent advances in nickel-based cocatalysts applied in photocatalytic H2 production, overall water splitting and CO2 reduction are summarized. This review highlights the various design strategies of nickel-based cocatalysts, including morphology modulation, interface engineering, and developing new nickel-contained cocatalysts. Besides, the mechanisms of nickel-based cocatalysts for promoting photocatalytic activities are systematically discussed from both theoretical and experimental aspects. Finally, perspectives on the challenges and opportunities for the further development of nickel-based cocatalysts are demonstrated.

The construction of multi-heteroatom-doped metal-free carbon with a reversibly oxygen-involving electrocatalytic performance is highly desirable for rechargeable metal-air batteries. However, the conventional approach for doping heteroatoms into the carbon matrix remains a huge challenge owing to multistep postdoping procedures. Here, a self-templated carbonization strategy to prepare a nitrogen, phosphorus, and fluorine tri-doped carbon nanosphere (NPF-CNS) is developed, during which a heteroatom-enriched covalent triazine polymer serves as a “self-doping” precursor with C, N, P, and F elements simultaneously, avoiding the tedious and inefficient postdoping procedures. Introducing F enhances the electronic structure and surface wettability of the as-obtained catalyst, beneficial to improve the electrocatalytic performance. The optimized NPF-CNS catalyst exhibits a superb electrocatalytic oxygen reduction reaction (ORR) activity, long-term durability in pH-universal conditions as well as outstanding oxygen evolution reaction (OER) performance in an alkaline electrolyte. These superior ORR/OER bifunctional electrocatalytic activities are attributed to the predesigned heteroatom catalytic active sites and high specific surface areas of NPF-CNS. As a demonstration, a zinc-air battery using the NPF-CNS cathode displays a high peak power density of 144 mW cm−2 and great stability during 385 discharging/charging cycles, surpassing that of the commercial Pt/C catalyst.

It is highly desirable to design an efficient photocatalysis system via manipulating electrons migration pathways for optimal hydrogen production from water splitting. Herein, flower-like MoSe2 has been employed as the co-catalyst to couple with cubic CdS nanoparticles for the in-situ construction of MoSe2/CdS heterojunction photocatalysts. Experimental investigations suggest that the photogenerated electrons can transfer across a space charge region between the MoSe2/CdS through the S–Mo–Se bonding, resulting in faster charge carriers separation and hence more long-lived electrons to participate in the hydrogen evolution reaction (HER). These insights are also supported by density functional theory (DFT)-based theoretical calculation. The dynamics of the photo-excited electrons was also investigated by ultrafast transient absorption spectroscopy. Furthermore, MoSe2 can afford more active sites for absorbing the protons for H2-evolution reactions, thereby accelerating the sluggish hydrogen evolution kinetics. Therefore, under visible-light irradiation, a remarkably enhanced photocatalytic H2 generation has been achieved in the MoSe2/CdS heterojunction (4.7 mmol g−1 h−1) compared to mechanically mixed sample (3.3 mmol g−1 h−1) and Pt-decorated CdS (1.3 mmol g−1 h−1). The external quantum efficiency of the MoSe2/CdS heterojunction toward HER has been determined to be 15.6% at 450 nm. This work not only provides a rational design for utilizing abundant elements to develop high-performance photocatalysts, but also pave the way to understand the photogenerated carriers transfer dynamics.

Graphitic carbon nitride (g-C3N4) is a well-known two-dimensional conjugated polymer semiconductor that has been broadly applied in photocatalysis-related fields. However, further developments of g-C3N4, especially in device applications, have been constrained by the inherent limitations of its insoluble nature and particulate properties. Recent breakthroughs in fabrication methods of g-C3N4 films have led to innovative and inspiring applications in many fields. In this review, we first summarize the fabrication of continuous and thin films, either supported on substrates or as free-standing membranes. Then, the novel properties and application of g-C3N4 films are the focus of the current review. Finally, some underlying challenges and the future developments of g-C3N4 films are tentatively discussed. This review is expected to provide a comprehensive and timely summary of g-C3N4 film research to the wide audience in the field of conjugated polymer semiconductor-based materials.

We report a bioinspired emulsion microreactor composed of an electrical double layer to mimic the functions of cell membranes. This "artificial cell"can modulate the phase-oriented transport of reagents at the oil-liquid interface via the electrical double layer, affording a powerful tool to optimize the selectivity in a catalytic reaction. This journal is

Solutions or sols are commonly employed as the starting materials for the preparation of supramolecular hydrogels; however, suspension-based synthesis has been much less reported because of inhomogeneity and quick sedimentation of large particles in a suspension. Further, it remains a technical challenge to derive supramolecular aerogels directly from the parental hydrogels owing to the ease of structural collapse during water removal. Herein, we report a suspension-gel transition for the ultrafast synthesis of a new supramolecular hydrogel simply by adding AgNO3 into the aqueous suspension of cyanuric acid-melamine (CAM) aggregates. With the activation of preadded ammonia, Ag ions instantly reacted with the CAM particles, transforming into N-Ag(I)-N coordinating bonded supramolecular nanofibers; simultaneously, the suspension converted to a hydrogel without the use of polymer cross-linkers or external stimulus. Upon simple freeze-drying, a highly crystalline fibrous aerogel with a cellular network was obtained, which possessed a porosity up to 99.7% and a density as low as 4.8 mg/cm3, enabling remarkable oil uptake capacities (100 times of its weight). The supramolecular aerogel demonstrated intrinsic elasticity, which should arise from the cellular structure and elastic character of the nanofiber skeletons. Notably, the aerogel showed high compatibility to incorporate a range of external substances for further functionalization exemplified by polymeric carbon nitride (PCN, a metal-free semiconductor) included gels. The loaded PCN resulted in enhanced mechanical strength and endowed the aerogel unique photoactivity, i.e., in situ reducing Ag(I) into Ag nanoparticles upon light illumination and thus forming a plasmonic shell over the aerogel with potential applications in sensing and catalysis.

Hydrogen-rich organic molecules such as alcohols are widely used as hydrogen donors in transfer hydrogenation. Nevertheless, water as a more abundant and ecofriendly hydrogen source has hardly been used due to the high difficulty in splitting water molecules. Herein, we designed a photocatalytic water-donating transfer hydrogenation (PWDTH) technique, in which hydrogen was extracted from water under light illumination and then in situ added to different unsaturated bonds (C-C, C-O, N-O) for chemical synthesis. Platinum-loaded carbon nitride (Pt/CN) was used as the model catalyst for this cascade reaction, which is beyond its normal applications for water splitting. This approach was highly accessible to efficiency optimization, either by modifying CN for extended light absorption and enhanced charge transfer or by alloying Pt with another metal for better catalytic activities. Remarkably, a quantum efficiency of up to 21.8% was achieved for nitrobenzene hydrogenation under 380 nm irradiation, which is 3 times higher than that obtained in the single water-splitting reaction, indicating that the PWDTH can be more rewarding than hydrogen evolution for solar energy harvesting. Deep insights into the underlying mechanism were provided by detailed measurements and interpretations of femtosecond transient absorption spectra, action spectra (quantum efficiency as a function of excitation wavelength), and reaction kinetic profiles under varied conditions including the variation of light intensities, temperatures, and water isotopes. The mild reaction conditions, simple processing, and broad substituent group tolerance endow this approach with a high potential toward a general solar-to-chemical conversion technique.

Two-dimensional (2D) nanosheet-based nanocomposites have attracted intensive interest owing to the unique electronic and optical properties from their constituent phases and the synergistic effect from the heterojunctions. In this study, an interfacial coupled TiO2/g-C3N4 2D-2D heterostructure has been prepared via in situ growth of ultrathin 2D-TiO2 on dispersed g-C3N4 nanosheets. This strongly coupled 2D-2D TiO2/g-C3N4, different from the weakly bonded 2D-TiO2/g-C3N4 heterostructures produced by mechanical mixing, has unique electronic structures and chemical states due to strong interlayer charge transfer, confirmed by both experimental and theoretical analyses. Significantly enhanced visible-light responses have been observed, indicating a great potential for visible-light induced photosynthesis and photocatalysis. For benzylamine coupling reactions under visible-light irradiation, 80 % yield rate has been achieved, superior to ∼30 % yield rate when adopting either 2D-TiO2 or g-C3N4 structure. The enhanced photocatalytic activity can be attributed to the adequate separation of photo-generated electrons at the strongly coupled 2D-2D heterojunction interfaces.

The lack of precise control of particle sizes is the critical challenge in the assembly of 3D interconnected transition-metal oxide (TMO) for newly-emerging energy conversion devices. A self-embedded templating strategy for preparing the TMO@carbon quasiaerogels (TMO@C-QAs) is proposed. By mimicking an aerogel structure at a microscale, the TMO@C-QA successfully assembles size-controllable TMO nanoparticles into 3D interconnected structure with surface-enriched carbon species. The morphological evolutions of intermediates verify that the self-embedded Ostwald ripening templating approach is responsible for the dual-channel TMO@C-QA formation. The general self-embedded templating strategy is easily extended to prepare various TMO@C-QAs, including the Co3O4@C-QA, Mn3O4@C-QA, Fe2O3@C-QA, and NiO@C-QA. Benefiting from the unparalleled 3D interconnected network of aerogels, the Co3O4@C-QA displays superior bifunctional catalytic activities for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), as well as high specific capacity and excellent long-term stability for lithium-ion battery (LIB) anode. A proof-of-concept battery-powered electrolyzer with Co3O4@C-QA cathode and anode powered by a full LIB with Co3O4@C-QA anode is presented. The battery-powered electrolyzer made of the state-of-the-art TMOs can exhibit great competitive advantages due to its supreme multifunctional energy conversion performance for future water electrolysis.

A solid photothermal reservoir is designed to implement solar-steam generation in the absence of bulk water. The photothermal reservoir is composed of a water absorbing core encapsulated by a photothermal reduced graphene oxide based aerogel sheet which absorbs light and converts it into heat thus evaporating the stored water. The photothermal reservoir is able to store 6.5 times its own weight in water, which is sufficient for one day solar evaporation, thus no external water supplement is required. During solar-steam generation, since no bulk water is involved, the photothermal reservoir minimizes heat conduction loss, and maximizes both of the exposed evaporation surface area and net energy gain from the environment, leading to an energy efficiency beyond the theoretical limit. An extremely high water evaporation rate of 4.0 kg m−2 h−1 (normalized to projection area) is achieved in laboratory studies over a cylinder photothermal reservoir with a diameter of 5.2 cm and a height of 15 cm under 1.0 sun irradiation. Practical evaluation of the photothermal reservoir outdoors as part of a desalination device demonstrates a similar evaporation rate where the salinity of the clean water produced is lower than 24 ppb. Thus the photothermal reservoir shows great potential for real world applications in portable solar-thermal desalination.

Major challenges in developing 2D transition-metal disulfides (TMDs) as anode materials for lithium/sodium ion batteries (LIBs/SIBs) lie in rational design and targeted synthesis of TMD-based nanocomposite structures with precisely controlled ion and electron transport. Herein, a general and scalable solvent-exchange strategy is presented for uniform dispersion of few-layer MoS2 (f-MoS2) from high-boiling-point solvents (N-methyl-2-pyrrolidone (NMP), N,N-dimethyl formaldehyde (DMF), etc.) into low-boiling-point solvents (water, ethanol, etc.). The solvent-exchange strategy dramatically simplifies high-yield production of dispersible MoS2 nanosheets as well as facilitates subsequent decoration of MoS2 for various applications. As a demonstration, MoS2-decorated nitrogen-rich carbon spheres (MoS2-NCS) are prepared via in situ growth of polypyrrole and subsequent pyrolysis. Benefiting from its ultrathin feature, largely exposed active surface, highly conductive framework and excellent structural integrity, the 2D core–shell architecture of MoS2-NCS exhibits an outstanding reversible capacity and excellent cycling performance, achieving high initial discharge capacity of 1087.5 and 508.6 mA h g−1 at 0.1 A g−1, capacity retentions of 95.6% and 94.2% after 500 and 250 charge/discharge cycles at 1 A g−1, for lithium/sodium ion storages, respectively.