Despite great prospects, Zn//MnO2 batteries suffer from rampant and vertical deposition of zinc sulfate hydroxide (ZSH) at the cathode surface, which leads to a significant impact on their ...electrochemical performance. This phenomenon is primarily due to the drastic increase in the electrolyte pH value upon discharging, which is closely associated with the electrodissolution of Mn‐based active materials. Herein, the pH value change is effectively inhibited by employing an electrolyte additive with excellent pH buffering capability. As such, the formation of ZSH at the cathode is postponed, resulting in the deposition of ZSH in a horizontal arrangement. This strategy can significantly enhance the utilization efficiency of cathode active material, while also enabling a solid electrolyte interphase layer at the Zn anode to address low Zn stripping/plating reversibility. With the optimal electrolyte, the Zn//MnO2 battery realizes a 25.6% increase in the specific capacity at 0.2 A g−1 compared to that with the baseline electrolyte, great rate capability (161.6 mAh g−1 at 5 A g−1), and superior capacity retention (90.2% over 5,000 cycles). In addition, the pH buffering strategy is highly applicable in hydrogel electrolytes. This work underscores the importance of pH regulation for Zn//MnO2 batteries and provides enlightening insights.
In order to mitigate the detrimental effects of dramatic pH increases in Zn//MnO2 batteries upon discharging due to the electrodissolution of MnO2, an electrolyte additive with exceptional pH buffering capability has been introduced. This can effectively suppress rampant and vertical deposition of zinc hydroxide sulfate intermediate product at the cathode, thereby significantly improving the electrochemical performance of Zn//MnO2 batteries.
Molybdenum disulfide (MoS2) nanosheets have been attracting increasing research interests due to their unique material properties. However, the lack of a reliable large‐scale production method ...impedes their practical applications. Here a facile, efficient, and scalable method for the fabrication of high‐concentration aqueous dispersion of MoS2 nanosheets using combined grinding and sonication is reported. The 26.7 ± 0.7 mg/mL concentration achieved is the highest concentration in an aqueous solution reported up to now. Grinding generates pure shear forces to detach the MoS2 layers from the bulk materials. Subsequent sonication further breaks larger crystallites into smaller crystallites, which promotes the dispersion of MoS2 nanosheets in ethanol/water solutions. The exfoliation process establishes a new paradigm in the top‐down fabrication of 2D nanosheets in aqueous solution. In the meantime, MoS2‐based sensing film produced using this approach has successfully demonstrated the feasibility of a low‐cost and efficient NH3 gas sensor using inkjet printing as a viable method.
The lack of a reliable large‐scale production method inhibits practical applications of MoS2 nanosheets. To address this, a facile, efficient, and scalable method for the fabrication of high‐concentration aqueous dispersion of MoS2 nanosheets using combined grinding and sonication is developed. The exfoliation process establishes a new paradigm in the top‐down fabrication of 2D nanosheets in aqueous solution.
Ultralong, highly oriented Ni nanowire arrays are used as the electrode scaffold to support metal‐oxide‐ and conductive‐polymer‐based electrode materials with a high mass loading; the as‐obtained ...asymmetric supercapacitor can be compressed by fourfold and exhibits superior energy and power densities with ultrahigh cycle stability.
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Hexagonal boron nitride (hBN) is an ultra-wide bandgap insulating material, which possesses a graphite-like layered structure, and the two-dimensional (2D) hexagonal boron nitride ...nanosheets (hBNNS), exfoliated from the bulk hBN, have promising applications in electronic packaging and high-power devices, due to the high thermal conductivity, excellent thermal/chemical stability as well as the ultra-wide band gap. However, the exfoliation of hBNNS is still a challenge with respect to high cost, time consuming, and low yield. Herein, a facile hydrothermal exfoliation method was proposed for the first time to exfoliate the hBNNS in a large yield and high concentration. In the optimized hydrothermal conditions, the lithium ion (Li+) intercalation, isopropanol (IPA) solvent, and the strong stirring could give rise to a large exfoliation yield up to ∼55% and a high concentration ∼4.13 mg/mL. In addition, the exfoliated hBNNS could enhance the methyl orange (MO) photodegradation efficiency of TiO2 from 91% to 96.4 %. Most importantly, this hydrothermal exfoliation method could be a universal approach for the exfoliation of 2D materials.
Wide bandgap (WB) organic–inorganic hybrid perovskites (OIHPs) with a bandgap ranging between 1.7 and 2.0 eV have shown great potential to improve the efficiency of single‐junction silicon or ...thin‐film solar cells by forming a tandem structure with one of these cells or with a narrow bandgap perovskite cell. However, WB‐OIHPs suffer from a large open‐circuit voltage (Voc) deficit in photovoltaic devices, which is associated with the phase segregation of the materials under light illumination. In this work the photoinstability is demonstrated and Voc loss can be addressed by combining grain crystallization and grain boundary passivation, achieved simultaneously through tuning of perovskite precursor composition. Using FA0.17Cs0.83PbI3–xBrx (x = 0.8, 1.2 1.5, and 1.8), with a varied bandgap from 1.72 to 1.93 eV, as the model system it is illustrated how precursor additive Pb(SCN)2 should be matched with a proper ratio of FAX (I and Br) to realize large grains with defect‐healed grain boundaries. The optimized WB‐OIHPs show good photostability at both room‐temperature and elevated temperature. Moreover, the corresponding solar cells exhibit excellent photovoltaic performances with the champion Voc/stabilized power output efficiency reaching 1.244 V/18.60%, 1.284 V/16.51%, 1.296 V/15.01%, and 1.312 V/14.35% for WB‐OIHPs with x = 0.8, 1.2, 1.5, and 1.8, respectively.
The photoinduced phase segregation in wide bandgap hybrid perovskites are greatly suppressed by combining grain crystallization and grain boundary passivation. As a result, the open‐circuit voltage (Voc) loss of the corresponding devices is highly reduced, demonstrating a monotonic increase of Voc with increasing of bandgap from 1.72 to 1.93 eV.
Mixed iodide‐bromide organolead perovskites with a bandgap of 1.70–1.80 eV have great potential to boost the efficiency of current silicon solar cells by forming a perovskite‐silicon tandem ...structure. Yet, the stability of the perovskites under various application conditions, and in particular combined light and heat stress, is not well studied. Here, FA0.15Cs0.85Pb(I0.73Br0.27)3, with an optical bandgap of ≈1.72 eV, is used as a model system to investigate the thermal‐photostability of wide‐bandgap mixed halide perovskites. It is found that the concerted effect of heat and light can induce both phase segregation and decomposition in a pristine perovskite film. On the other hand, through a postdeposition film treatment with benzylamine (BA) molecules, the highly defective regions (e.g., film surface and grain boundaries) of the film can be well passivated, thus preventing the progression of decomposition or phase segregation in the film. Besides the stability improvement, the BA‐modified perovskite solar cells also exhibit excellent photovoltaic performance, with the champion device reaching a power conversion efficiency of 18.1%, a stabilized power output efficiency of 17.1% and an open‐circuit voltage (V
oc) of 1.24 V.
Using a postdeposition film treatment with benzylamine (BA) molecules, the highly defective regions of the wide‐bandgap FA0.15Cs0.85Pb(I1−
x
Br
x
)3 films can be well passivated, thus preventing the progression of decomposition or phase segregation in the film during combined heat and light stress. The BA‐treated perovskite solar cells exhibit a stabilized power output efficiency of 17.1% and an open‐circuit voltage (V
oc) of 1.24 V.
Achieving effective dropwise capture and ultrafast water transport is essential for fog harvesting. In nature, cactus uses the conical spine with microbarbs to effectively capture fog, while ...Sarracenia utilizes the trichome with hierarchical microchannels to quickly transport water. Herein, we combined their advantages to present a novel configuration, a spine with barbs and hierarchical channels (SBHC), for simultaneous ultrafast water transport and high-efficient fog harvesting. This bioinspired SBHC exhibited the fastest water transport ability and the highest fog harvesting efficiency in comparison with the spine with hierarchical channels (SHCs), the spine with barbs and grooves (SBG), and the spine with barbs (SB). Based on the fundamental SBHC unit, we further designed and fabricated a two-dimensional (2D) spider-web-like fog collector and a three-dimensional (3D) cactus-like fog collector using direct laser structuring and origami techniques. The 2D spider-web and 3D cactus-like fog collectors showed high-efficient fog collection capacity. We envision that this fundamental understanding and rational design strategy can be applied in fog harvesting, heat transfer, liquid manipulation, and microfluidics.
Stretchable and flexible sensors attached onto the surface of the human body can perceive external stimuli, thus attracting extensive attention due to their lightweight, low modulus, low cost, high ...flexibility, and stretchability. Recently, a myriad of efforts have been devoted to improving the performance and functionality of wearable sensors. Herein, this review focuses on recent remarkable advancements in the development of flexible and stretchable sensors. Multifunction of these wearable sensors is realized by incorporating some desired features (e.g., self-healing, self-powering, linearity, and printing). Next, focusing on the characteristics of carbon nanomaterials, nanostructured metal, conductive polymer, or their hybrid composites, two major strategies (e.g., materials that stretch and structures that stretch) and diverse design approaches have been developed to achieve highly flexible and stretchable electrodes. Strain sensing performances of recently reported sensors indicate that the appropriate choice of geometric engineering as well as intrinsically stretchable materials is essential for high-performance strain sensing. Finally, some important directions and challenges of a fully sensor-integrated wearable platform are proposed to realize their potential applications for human motion monitoring and human–machine interfaces.
Well-ordered, hierarchical and nanostructured composite electrodes have gained tremendous research attention for energy storage applications, because of their highly efficient electron and ion ...transport channels and abundant electrochemically active sites. However, it still remains a great challenge to prepare such architectures on a large scale with high active material mass loadings for making better use of the whole electrode area. Herein, needle-like NiCo2S4 nanowhiskers are radially grown on a uniform nickel nanowire array (NNA), forming a unique densely packed test-tube-brush-like nanostructure. Since these NiCo2S4 nanowhiskers are intrinsically highly electrically conductive, the hierarchical electrode structure can drastically elevate the charge transport ability in the whole electrode region; additionally, it can greatly help to release stresses at micro- and nano-scales, leading to robust mechanical flexibility and superior energy storage capability. Experimental results show that this composite array electrode exhibits an ultrahigh specific capacitance of 1523 F g−1 at a mass loading of 4.03 mg cm−2 at a current density of 1 A g−1, and a rate capability of 61.8% from 1 to 40 A g−1, together with a superior cycle stability with 92.4% capacitance retention after 20 000 cycles at a current density as high as 10 A g−1. An asymmetric supercapacitor consisting of a NNA@NiCo2S4 (NNANCS) cathode and activated carbon (AC) anode delivers a maximum energy density of 47.29 W h kg−1 at a power density of 793.5 W kg−1 and still delivers an energy density of 29.50 W h kg−1 at a maximum power density of 27.64 kW kg−1. This work may inspire new ideas for constructing high-performance electrodes for energy storage.
Filter capacitors (FCs) are substantial for digital circuits and microelectronic devices, and thus more compact FCs are eternally demanded for system miniaturization. Even though microsupercapacitors ...are broadly regarded as an excellent candidate for future FCs, yet due to the limitation of available electrode materials, the capacitive performance of reported MSCs drops sharply under high‐frequency alternating current. Herein, we present a unique laser‐induced transient self‐organization strategy, which synergizes pulsed laser energy and multi‐physical field controlled coalescence processes, leading to the rapid and controllable preparation of titanium nitride ultrafine nano‐filaments (diameter ≈3–5 nm) networks. Their chaotic fractal nanoporous structure, superior specific surface area, and excellent conductivity render these nanostructures promising candidates for FCs. Surface‐mounted filter capacitors based on this electrode material exhibit ultra‐long cycle‐life (2 000 000 cycles) with record ultrahigh volumetric energy density of 9.17 mWh cm−3 at 120 Hz in aqueous electrolyte, displaying advantages in function, size, and integrability compared with the state‐of‐the‐art aluminum electrolytic capacitors. The method here provides a versatile toolbox for designing novel nanostructures with intriguing characteristics and insights for developing advanced and miniaturized filter and power devices.
Preparing low‐dimensional conductive nitride‐based hierarchical structures with sub‐10 nm geometric characteristics has been a major challenge. A unique laser‐induced transient self‐organization strategy to rapidly and controllably fabricate ultrafine (diameter: 3–5 nm) TiNx nano‐filament percolated chaotic fractal networks is presented. The prepared surface‐mountable filter capacitors achieve a record‐breaking volumetric energy density of 9.17 mWh cm−3 at 120 Hz in an aqueous electrolyte.
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