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Atom-intercalated transition metal disulfides (TMDs) have attached much attention mainly due to their highly improved conductivity. But it is few reported that the atom intercalation can enable the TMDs have unexpected catalytic properties, caused by the unit-cell deformation in them. In this work, a type of V0.25-intercalated VS2 (V5S8) nanoflakes was designed via a direct vulcanization method combining Kirkendall heat diffusion effect, and used as the promotor for lithium-sulfur batteries (LSBs). The V5S8 possesses a NiAs crystal structure, in which V atoms occupy the interlayer spacing between VS2 monolayers, which will unavoidably cause the unit-cell deformation. As expected, the CNF@V5S8/S cathodes show a specific capacity of 1260 mAh g−1 at 0.2 C, and can keep 73.65% of the capacity with charge/discharge rate increasing 10 times; while the CNF@VS2/S ones can only retain 54.0% of the initial capacity. Moreover, the CNF@V5S8/S cathodes show an ultralow decay rate of only 0.0312% per cycle for 1500 cycles at 5 C. Furthermore, the catalysis effect of V5S8 on the conversion of lithium polysulfide (Li2Sn, n = 1, 2, 4, 6 and 8) and S8 clusters were systematically discusses. Besides, the V5S8 can further enable LSBs achieve a high areal capacity (8.2 mAh cm−2 with sulfur loading of 7.8 mg cm−2) and a high dynamic flexible stability at bending angle between 0 and 180 °.

Lithium-sulfur batteries (LSBs) are still limited by the shuttle of lithium polysulfides (LiPS) and the slow Li-S reaction. Herein, we demonstrate that when using cobalt sulfide as a catalytic additive, an external magnetic field generated by a permanent magnet can significantly improve the LiPS adsorption ability and the Li-S reaction kinetics. More specifically, the results show both experimentally and theoretically how an electron spin polarization of Co ions reduces electron repulsion and enhances the degree of orbital hybridization, thus resulting in LSBs with unprecedented performance and stability. Under an external magnetic field, LSBs with 0.0084 % per cycle decay rate at 2 C during 8150 cycles are produced. Overall, this work not only demonstrates an effective strategy to promote LiPS adsorption and electrochemical conversion in LSBs at no additional energy cost but also enriches the application of the spin effect in the electrocatalysis fields., This work was supported by the National Natural Science Foundation of China (Grant Nos.: 51572118 and 21975123) and partially by the Fundamental Research Funds for the Central Universities (Grant Nos.: lzujbky-2021-it33). C. Y. Zhang, C. Q. Zhang, and L. Gong thank the China Scholarship Council for the scholarship support. A. Cabot thanks financial support from the Combenergy project (PID2019-105490RB-C32) from the Spanish Ministerio de Ciencia e Innovación. The authors also greatly acknowledge the support supported by the Supercomputing Center of Lanzhou University, China., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

SnO2/TiO2 type II heterojunctions are often introduced to enhance the separation efficiency of photogenerated carriers in photoelectrochemical electrodes, while most of these heterojunctions are of core–shell structure, which often limits the synergistic effect from the two components. In this work, dissymmetric SnO2/TiO2 side-by-side bi-component nanofibers (SBNFs) with tunable composition ratios have been prepared by a novel needleless electrospinning technique with two V-shape connected conductive channels (V-channel electrospinning). Results show that this V-channel electrospinning technique is more stable, controllable and tunable for the large-scale preparation of SBNF materials compared to the traditional electrospinning using two side-by-side metal needles. And these SnO2/TiO2 SBNFs are dissymmetric and comprised of a tiny SnO2 NF (tunable diameter within 20–80 nm) and a Sn-doped TiO2 NF (diameter of ~ 250 nm) with a side-by-side structure. Moreover, the dye-sensitized solar cells (DSSCs) based these dissymmetric SnO2/TiO2 SBNFs show the maximum power conversion efficiency (PCE) of 8.3%, which is 2.59 times that of the ones based on the TiO2 NFs. Series of analyses indicate that the enhancements in PCE could mainly be due to the improved electron transport via SnO2 NFs and the enhanced carrier separation via dissymmetric SnO2/TiO2 heterojunction interface. This research will give some new insight in the preparation of SBNFs for high-performance photoelectrochemical devices.

It was demonstrated that the electrochemical performance enhancements in KOH-activated carbon materials should be mainly due to the created polar oxygen-containing functional groups (OFGs, such as such as C–O, C O, –OH, and O–C O), while the role of each OFGs on the electrochemical enhancements is still unclear. In this work, KOH activation treatments were systematically conducted on carbon nanotubes (CNTs) to explore the role of each OFG on the performance enhancements of Li–S batteries (LSBs). Results showed that the capacity of activated-CNT-sulfur (a-CNT-S) cathodes is 33% higher than that of the pristine CNT-S cathodes, and their rate capability and cycling stability are also enhanced. And the electrochemical analysis combining with Fourier transform infrared spectroscopy indicated that the formed C–O bonds are the real factor for the enhanced electrochemical performances of a-CNT-S cathodes. Furthermore, the optimal activation conditions on CNT-based cathodes for LSBs were optimized to be 10 min at 700 °C.

Vanadium sulfides, such as VS2, have been often used as sulfur host materials for lithium–sulfur batteries (LSBs), however, their high-symmetry and layered crystalline structure often lead to a poor rate-capability and a limited cycling stability of the resultant LSBs. Thus, in this work, a type of distorted NiAs-type structured V2S3 phase was designed and attempted to use it as a sulfur host for LSBs. The results showed that the prepared V2S3-nanocrystal decorated carbon nanofiber (CNF@V2S3) electrode films are freestanding, highly conductive and flexible. And the resultant CNF@V2S3/S cathodes show a high specific capacity (1169 mA h g−1 at 0.1C), an excellent rate capability (retain 78.9% at 2.0C), an ultra-low delay rate per cycle of 0.0071%, and a low self-discharge rate of 3.65% per month. A series of analyses indicate that these high electrochemical performances are mainly due to the high polarity, high conductivity and high catalytic activity of V2S3 nanocrystals, as well as the improved diffusivities of Li ions. This research could provide some new insight into the design of sulfur host materials for high-performance LSBs.

Carbon nanotubes (CNTs) and their related hybrids grown by chemical vapor deposition (CVD) method have been frequently used as energy-storage electrode materials. In most cases, the tips of CNTs are almost well closed, which often limits the utilization efficiency of their tubular structure in storage of charges. In this work, the authors have designed a type of tip-open CNT/CNF hierarchical hybrids via KOH activation on the CVD-grown Al/Fe-catalyzed CNT/CNF precursors. Results showed that the CNT hierarchies' tips can be fully opened via KOH activation at 700–750 °C for 90 min. As expected, the tip-open CNT-CNF hybrids show a highly improved specific capacitance, which increases by 3.3 times that of the pristine ones. Moreover, sweep analysis indicated that the diffusion-type capacitance increases by 3.7 times while the Helmholtz-type capacitance increases only by 1.5 times, indicating that the tip-open CNTs contribute to ∼30% of the increase in double-layer capacitance. Further optimization on activation time and temperature indicated that activation at 700 °C for 90 min is suitable for opening the tips of CNT hierarchies and protecting the CNTs’ tubular structure. This research would give some useful advice for the preparation of high-performance CNT-related electrode materials for energy storage.

SnO

It’s demonstrated that the defects induced by doping can greatly influence the sensing properties of oxide-based gas sensors. In this work, the authors have designed indium tin oxide nanotubes (ITO NTs) with different Sn doping concentrations. Results showed that the walls of ITO NTs are comprised of the formed ITO and redundant In2O3 nanoparticles (NPs) at low doping concentration, and the doping-induced oxygen vacancies ( V o · · S ) can be tuned by Sn concentrations. Series of sensing tests to formaldehyde gas indicated that the ITO-7 NTs show the lowest working temperature (160 °C) and the highest specific response. Here, It is noted that to eliminate the influence of the coating amount of sensing performances, a concept of specific response was proposed i.e., Rair/(m–Rgas), where Rair and Rgas respectively stand for the resistances of gas sensors in the reference gas (in air this case) and in the test gas ambience, and m stands for the mass of the coated sensing materials. The decreased working temperature could be attributed to the formed In2O3 NPs/ITO tubular structure, and the enhanced specific response might be mainly associated with the V o · · S . Furthermore, a possible gas sensing enhancing mechanism via V o · · S for ITO-based gas sensors was proposed based on our results and analysis. This research would give some instructive advice to design high-performances oxide-based gas sensors via tuning the V o · · S .

It is reported that the response is dependent on its specific surface area, and the response/recovery rates are on the electron transfer channels. In this work, the authors have designed a type of fluffy hematite (α-Fe2O3) microtubes. Results indicate that these fluffy α-Fe2O3 microtubes are highly porous and composed of interconnected ultrafine nanorods. And the assembled gas sensors show a response of 16.8 to 100-ppm ethanol gas at 260 °C, the response time is of 2 s and the recovery time is of 25 s. Moreover, the sensors also show good gas selectivity and long-term stability.

Ordered array structures will greatly reduce the stress formation in wearable electric devices during dynamic bending operation. In this work, highly flexible TiN-based fiber counter electrodes (FCEs) were designed via a post-ammonization treatment on the hydrothermally grown TiO2 nanowire arrays. Results show that the obtained TiN nanorod arrays (NRAs) are well aligned with a diameter of 200–320 nm and a length of several hundred nanometers to ∼1 μm. Moreover, fiber-shaped dye-sensitized solar cells assembled using TiN FCEs showed the maximum photoelectric conversion efficiency (PCE) of 5.69%, which is 16.3% higher than that of the ones based on Pt FCEs. Analysis indicated that this enhancement in PCE could be mainly due to the better electrochemical catalytic activity of TiN NRAs. Furthermore, the optimizations of the nanoscale morphologies of TiN NRAs suggest that both small diameters and large lengths can benefit the PCE and the dynamic bending stability, while the diameters show a major influence on them. The optimal FCEs show an ultralow decay rate of 0.017‰ per bending cycle.

Post-grown hierarchical pseudocapacitive nanostructures often suffer from their bad long-term cycling stability. In this work, a type of hierarchical partially-embedded MnO nanocube/electrospun carbon nanofiber composites (pe-MnO/ECNFs) was designed. Results show the MnO nanocubes are partially embedded into the ECNFs skeletons, showing a strong joint between them. The pe-MnO/ECNFs electrodes exhibit a high specific capacitance of 146 F g−1 (to the whole electrode mass) at scan rate of 5 mV s−1, and an ultralow decay rate of 0.004‰ per cycle for 20,000 cycles at 10 A g−1, which is much better than those of the MnO2/ECNF ones (96 F g−1, decay rate of 0.015‰ per cycle). Furthermore, the assembled flexible symmetric supercapacitors show an high energy density of 6.8 W h kg−1, a high dynamic bending stability, and a robust long cycling stability (low decay rate of 0.003‰ per cycle for 6000 cycles at 1 A g−1).

To enhancing enhanced sunlight harvesting, long persistence phosphor (LPP) materials were often incorporated into photoanodes of photoelectric devices. However, the role of LPP layer on the photoelectric enhancements is not yet clear. Here, the authors have systematically studied the effect of green LPP (SrAl2O4: Eu3+) and its thickness on photoelectric behaviours of dye-sensitized solar cells (DSSCs). Results showed that the P25/LPP DSSCs generates power conversion efficiency (PCE) of 7.16% at the optimal LPP thickness, which is 24.3% higher than that of the P25 ones. Series of analysis indicate that the enhancements in short-circuit current density and PCE could mainly be due to the LPP’s function of back scattering (containing down-conversion effect and enhancement in light absorption) of incident sunlight. Moreover, the enhanced carriers’ lifetime and open-circuit voltage are mainly due to the LPP layer’s afterglow effect. In addition, the P25/LPP DSSCs can still generate an output power density (82.15 μW cm−2) with a high PCE value of 46.94% in dark.

Carbon nanomaterials have been frequently used to physically inhibit the lithium polysulfide's shuttle in lithium–sulfur batteries, especially those crumpled structure of graphene. Here, a type of reduced graphene oxide fiber enwrapped nano-sulfur (rGOF@nano-S) hybrids were synthesized by a simple sulfur-containing-ion assisted microwave (MW) synthesis method and then utilized as a sulfur host for lithium–sulfur batteries. The synergistic reactions of MW treatments and sulfur-containing-ion force on the precursor GO nanosheets (NSs) have induced a well-crumpled fibrous structure, and simultaneously uniformly wrapped the nano-S particles in them, which would make the resultant cathodes achieve improved electrochemical performances. The rGOF@nano-S hybrid cathodes showed a high reversible capacity (886 mA h g−1 at 0.1 C rate), a high rate capability (remaining 61% at 2 C rate), and an excellent cycling stability (with a minimal decay rate of 0.04% per cycle over 800 cycles at 1 C), which are highly improved compared to those of the hybrids without MW treatments. In addition, the optimal MW treatment time on rGOF@nano-S hybrid cathodes were also explored to be 2.4 min under 700-W power. This work suggests that MW treatments would be a useful strategy for the preparation of high-performance cathodes for Li–S batteries.

Woven into your memories: Aligned multi-walled carbon nanotube (MWCNT) fibers are coated by a thin layer of graphene oxide (GO). The MWCNT fibers work as the top and bottom electrodes while the GO acts as the active layer. By simply cross-stacking two MWCNT@GO fibers, the memory cell obtained shows a write-once-read-many-times effect (see picture).

It is demonstrated that the incorporation of graphene materials into oxide-based photoanodes can greatly increase the photoelectrochemical devices' performances. In this work, reduced graphene oxide (rGO) has been incorporated into P25-TiO2 nanoparticle (NP) based photoanodes for fiber-shaped dye-sensitized solar cells (FDSSCs). Results showed that the rGO nanosheets have been uniformly dispersed within P25 nanopanicle layers, and, as expected, the incorporation of rGO increased the FDSSCs' short current density from 8.344 to 12.935 mA cm(-2), open circuit voltage from 0.775 to 0.798 V, resulting into their power conversion efficiency (PCE) from 3.940% to 5.364%. This large increasement in PCE could be due to two aspects, i.e. the improved electron transport properties via rGO and the enhanced separation of photogenerated hole-electron pairs via rGO-TiO2 heterojunction. Furthermore, the incorporation of rGO can also make the FDSSCs have good mechanical properties, which is very crucial for their future applications in smart wearable electronics. In addition, based on our analysis, a possible rGO/multi-NP coupling enhancement mechanism was proposed.