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The electrocatalytic reduction of nitrobenzene to aniline normally faces high overpotential and poor selectivity because of its six-electron redox nature. Herein, a Ag nanoparticles/laser-induced-graphene (LIG) heterointerface was fabricated on polyimide films and employed as an electrode material for an efficient nitrobenzene reduction reaction (NBRR) via a one-step laser direct writing technology. The first-principles calculations reveal that Ag/LIG shows the lowest activation barriers for the NBRR, which could be attributed to the optimum adsorption of the H atom realized by the appropriate interaction between Ag/LIG heterointerfaces and nitrobenzene. As a result, the overpotential of the NBRR is reduced by 217 mV after silver loading, and Ag/LIG shows a high aniline selectivity of 93%. Furthermore, an electrochemical reduction of nitrobenzene in tandem with an electrochemical oxidative polymerization of aniline was designed to serve as an alternative method to remove nitrobenzene from the aqueous solution. This strategy highlights the significance of heterointerfaces for efficient electrocatalysts, which may stimulate the development of novel electrocatalysts to boost the electrocatalytic activity.

Olefin epoxidation is an essential transformation and arouses great interest among the scientific community for the key role of epoxide in the chemical industry.

A multistep electron transfer process is realized over C12A7:e− electride composite material. The graphene promotes electron transfer from C12A7:e− through surface Pd to the aryl halide substrates, affording a series of cross-coupling reactions.

Iron difluoride (FeF2) is considered a high-capacity cathode material for lithium-ion batteries. However, its specific capacity and stability are limited by the poor electrochemical kinetics of conversion reactions. Herein, the conversion reaction is confined in a localized nanosized space by encapsulating FeF2 nanoparticles in polymer gelatin. The FeF2 nanocrystal-coated polyvinylidene fluoride-based layer (defined as FeF2@100%G-40%P) was synthesized by glucose-assisted in-situ gelatinization to construct an artificial cathode solid electrolyte interphase via a solvothermal process. Thanks to the improved kinetics of the localized conversion reaction, the obtained FeF2@100%G-40%P electrodes show good cyclic stability (313 mA h g−1 after 150 cycles at 100 mA g−1, corresponding to a retention of 80%) and a high rate performance (186.6 mA h g−1 at 500 mA g−1).

Broad absorption spectra with efficient generation and separation of available charge carriers are indispensable requirements for promising semiconductor-based photocatalysts to achieve the ultimate goal of solar-to-fuel conversion. Here, Cu3−xSnS4 (x = 0−0.8) with copper vacancies have been prepared and fabricated via solvothermal process. The obtained copper vacancy materials have extended light absorption from ultraviolet to near-infrared-II region for its significant plasmonic effects. Time-resolved photoluminescence shows that the vacancies can simultaneously optimize charge carrier dynamics to boost the generation of long-lived active electrons for photocatalytic reduction. Density functional theory calculations and electrochemical characterizations further revealed that copper vacancies in Cu3−xSnS4 tend to enhance hydrogen’s adsorption energy with an obvious decrease in its H2 evolution reaction (HER) overpotential. Furthermore, without any loadings, the H2 production rate was measured to be 9.5 mmol·h−1·g−1. The apparent quantum yield was measured to be 27% for wavelength λ > 380 nm. The solar energy conversion efficiency was measured to be 6.5% under visible-near infrared (vis-NIR) (λ > 420 nm).

Photocatalysis is considered a remarkable green method in the catalytic degradation of wastewater; however, the collection and loading of the powdered catalyst is still a problem. The traditional coating methods are usually unstable for the (photo-)degradation of organic binders. Herein, monolithic structures based on 2D–2D interactions instead of traditional 0D–0D and 1D–1D interactions were designed and constructed, realizing an interlocked structure with 3D active carbon fiber networks via the self-assembly of Bi2O2CO3 nanosheets (B-ACF) during the hydrothermal process. The loaded catalyst was further modified via an I-doping improvement strategy (4B-ACF-I), which exhibited 8 times the catalytic activity as compared to the intrinsic Bi2O2CO3. Thanks to the 3D monolithic and interlocked structure of loaded catalysts, B-ACF-I photocatalysts could be reused without any loss of catalytic activity during the cycling stability test. The expanded experiment and the removal of Cr(VI) under visible light prove that our improvement strategy can be considered even in actual wastewater treatment.

The NaTi2(PO4)3 (NTP) anode materials exhibit high Na+ diffusion dynamics; carbon-based materials can effectively improve its limited electronic conductivity. However, the low Na+ diffusion of NTP/C composite materials from inhomogeneous carbon mixing or uncontrollable carbon coating cannot keep up with fast electron transfer, leading to undesirable electrochemical performances. Herein, a uniform and controllable carbon layer is designed on the self-supported-coated NTP nanorod arrays with binder-free (NTP@C NR) to improve Na+ and electron kinetics simultaneously. As a result, the NTP@C NR electrodes possess initial coulombic efficiency (ICE = 97%), good rate capabilities (89.1 mA h g-1 at 100 C), and stability with ≈78.4% of capacity retention rate at even 30 C over 1200 cycles. The sodium-ion capacitors with NTP@C NR as an anode and commercially activated carbon as a cathode exhibit ∼9180.0 W kg-1 of power density at 10 A g-1 and super high retention of ≈94.5% at 1 A g-1 over 7000 cycles. This work will help balance transport kinetics between the ion and electron for materials applied in storage devices.

Electrocatalytic N2 reduction to ammonia is a fascinating alternative to Haber-Bosch process and also considered as an energy storage method. This work, Fe doped MoS2/carbon cloth (CC) has been studied on the electro-catalysis fix nitrogen indicating the doped Fe can indeed enhance the MoS2 material ability. Compared with MoS2/CC, Fe-Mo-S-3/CC not only increases 10 times in the rate of production ammonia, but also 5 times in Faraday efficiency.

In this work, grain boundary (GB) potential barrier ( Δφ GB), dopant density (Pnet), and filled trap state density (PGB,trap) were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative humidity (RH) environments. Spatial mapping of surface potential in the perovskite film revealed higher positive potential at GBs than inside the grains. The average Δφ GB, Pnet, and PGB,trap in the perovskite films decreased from 0% RH to 25% RH exposure, but increased when the RH increased to 35% RH and 45% RH. This clearly indicated that perovskite solar cells fabricated at 25% RH led to the lowest average GB potential, smallest dopant density, and least filled trap states density. This is consistent with the highest photovoltaic efficiency of 18.16% at 25% RH among the different relative humidities from 0% to 45% RH.

The gram-scale selective oxidation of biomass-based chemicals, in particular 5-hydroxymethylfurfural (HMF), into value-added 2,5-diformylfuran (DFF) has a high application potential but suffers from high cost, low selectivity, and harsh reaction conditions. Besides, the electrooxidation strategy requires the usage of expensive electrodes and struggles with low selectivity and efficiency, which restricts its further scaled-up application. In this regard, a continuous-flow system was developed through redox mediator I

Solar steam generation has great potential in alleviating freshwater crises, particularly in regions with accessible seawater and abundant insolation. Inexpensive, efficient, and eco-friendly photothermal materials are desired to fabricate sunlight-driven evaporation devices. Here, we have designed an economical strategy to fabricate a high-performance wood-based solar steam generation device. In current study, 3D-hierarchical Cu

Lithium-sulfur (Li-S) batteries, as a prospective energy storage system, are still plagued by many problems that prevent them from their application, especially the low content of sulfur in the cathode. Herein, a cathode material with S up to 93 wt % is designed via a hollow donor-π-acceptor heterosystem, which combines catalytic sites, adsorption sites, and good conductivity together. Following this guidance, a hollow porous carbon sphere is prepared with CoO particles and single V atoms decorated on it (Co/V-HPCS), providing ultrahigh volumetric space for sulfur. Even the electrode made of sulfur-loaded Co/V-HPCS (Co/V-HPCS@S) has a high content of 90 wt % (sulfur content in the electrode is ∼83.5 wt %), and the cathode exhibits an excellent discharge capacity of 575.2 mAh g-1 under 0.2C after 100 cycles. With careful analysis by means of a high-resolution transmission electron microscope (HRTEM), the catalytic amounts of CoO particles and single V atoms loaded on the carbon shell are confirmed, which endows the material with outstanding catalytic ability to transfer sulfur and excellent adsorption of polysulfides. This concept of the cathode material increases the possibility of advanced long-life Li-S batteries with high tap density and high energy density.

SnO2 is widely used for ethanol-sensing applications due to its excellent physicochemical properties, low toxicity and high sensitivity. However it is a challenge to construct 3D-hierarchical structures with sub 5 nm primary grain particle, which is the optimized size for ethanol sensor. Herein, genetic tri-level hierarchical SnO2 microstructures are synthesised by the genetic conversion of 3D hierarchical SnS2 flowers assembled by ultrathin nanosheets. The SnS2 nanosheets are morphology genetic converted to porous nanosheets with sub 5 nm SnO2 nanoparticles during the calcination process. When used for the detection of ethanol, the sensor exhibits a high sensitivity of 0.5 ppm (Ra/Rg = 6.8) and excellent gas-sensing response (Ra/Rg = 183 to 100 ppm) with short response/recovery time (12 s/11 s). The excellent gas sensing performance is much better than that of the previous reported SnO2-based sensors. The highly sensitivity is attributed to the large surface area derived from the recrystallization and volume changes, which offers more active sites during the morphology genetic conversion from SnS2 to SnO2. Furthermore, the flower-like 3D structure enhances the stability of the materials and is beneficial for the mass diffusion dynamics of ethanol.

Aqueous polysulfide/iodide redox flow batteries (RFBs) are an attractive candidate for scalable energy storage with highly soluble active materials, which show great potential to reduce RFB cost. However, their energy efficiency is usually limited by poor kinetics reversibility and electrochemical activity of the redox reaction of polysulfide couples on the graphite felt electrode, which hinder its further practical applications. Here, Cu2XGeS4 (X = Fe, Co, Ni, Cd, Mn) nanocrystals are successfully synthesized through the hot injection method, and then uniformly coated onto the surface of graphite felt as electrodes. These electrodes can successfully suppress the water splitting side reactions, especially the hydrogen evolution reaction. The ones with Cu2CoGeS4 nanocrystals can significantly boost electrocatalytic activities of S2−/Sx2− redox reactions for the proper adsorbability of polysulfide, which inturn improve the charge transfer process and selectively facilitate the electro-conversion reactions of polysulfides. Furthermore, the polysulfide/iodide flow battery with GF–Cu2CoGeS4 generates a high energy efficiency of 77.2% at 20 mA cm−2, a power density of 40.7 mW cm−2 and a stable energy efficiency retention of 92% after approximately 250 continuous cycles.

The modulation of electron density is an effective option for efficient alternative electrocatalysts. Here, p-n junctions are constructed in 3D free-standing FeNi-LDH/CoP/carbon cloth (CC) electrode (LDH=layered double hydroxide). The positively charged FeNi-LDH in the space-charge region can significantly boost oxygen evolution reaction. Therefore, the j at 1.485 V (vs. RHE) of FeNi-LDH/CoP/CC achieves ca. 10-fold and ca. 100-fold increases compared to those of FeNi-LDH/CC and CoP/CC, respectively. Density functional theory calculation reveals OH- has a stronger trend to adsorb on the surface of FeNi-LDH side in the p-n junction compared to individual FeNi-LDH further verifying the synergistic effect in the p-n junction. Additionally, it represents excellent activity toward water splitting. The utilization of heterojunctions would open up an entirely new possibility to purposefully regulate the electronic structure of active sites and promote their catalytic activities.

If counter electrodes (CEs) could also contribute to light harvesting in dye-sensitized solar cells (DSSCs), then the power conversion efficiency (PCE) of DSSCs would be further boosted without changing the device structure. Nearly monodispersed Ag2 Se nanocrystals with a bandgap of 1.62 eV (∼765 nm) were synthesized via a one-pot process, and Ag2 Se CEs were fabricated by using a spin-coating and annealing process. Incident photon-to-current conversion efficiency and photocurrent spectra indicated that Ag2 Se CEs can generate the electricity by harvesting more visible light, which could not be absorbed by dye-sensitized photoanodes. Thus, compared to Pt CE (7.57 %), the DSSC based on Ag2 Se CE exerted a higher PCE of 8.06 %. The development of photovoltaic CEs may offer an alternative way to promote the performance and competitiveness of DSSCs.

SnO

Silicon is a low price and high capacity anode material for lithium-ion batteries. The yolk-shell structure can effectively accommodate Si expansion to improve stability. However, the limited rate performance of Si anodes can’t meet people’s growing demand for high power density. Herein, the phosphorus-doped yolk-shell Si@C materials (P-doped Si@C) were prepared through carbon coating on P-doped Si/SiOx matrix to obtain high power and stable devices. Therefore, the as-prepared P-doped Si@C electrodes delivered a rapid increase in Coulombic efficiency from 74.4% to 99.6% after only 6 cycles, high capacity retention of ∼ 95% over 800 cycles at 4 A·g−1, and great rate capability (510 mAh·g−1 at 35 A·g−1). As a result, P-doped Si@C anodes paired with commercial activated carbon and LiFePO4 cathode to assemble lithium-ion capacitor (high power density of ∼ 61,080 W·kg−1 at 20 A·g−1) and lithium-ion full cell (good rate performance with 68.3 mAh·g−1 at 5 C), respectively. This work can provide an effective way to further improve power density and stability for energy storage devices.

Highlights γ-Glycidoxypropyl trimethoxysilane (GOPS) was incorporated in Si/PEDOT:PSS electrodes to construct a flexible and conductive artificial solid-electrolyte interphase (SEI). XPS Ar+ etching depth analysis proved that the addition of GOPS is conducive to forming a more stable SEI. A full battery assembled with NCM 523 cathode delivers a high energy density of 520 Wh kg-1, offering good stability. Electronic supplementary material The online version of this article (10.1007/s40820-020-00564-5) contains supplementary material, which is available to authorized users., Huge volume changes of Si during lithiation/delithiation lead to regeneration of solid-electrolyte interphase (SEI) and consume electrolyte. In this article, γ-glycidoxypropyl trimethoxysilane (GOPS) was incorporated in Si/PEDOT:PSS electrodes to construct a flexible and conductive artificial SEI, effectively suppressing the consumption of electrolyte. The optimized electrode can maintain 1000 mAh g−1 for nearly 800 cycles under limited electrolyte compared with 40 cycles of the electrodes without GOPS. Also, the optimized electrode exhibits excellent rate capability. The use of GOPS greatly improves the interface compatibility between Si and PEDOT:PSS. XPS Ar+ etching depth analysis proved that the addition of GOPS is conducive to forming a more stable SEI. A full battery assembled with NCM 523 cathode delivers a high energy density of 520 Wh kg−1, offering good stability. Electronic supplementary material The online version of this article (10.1007/s40820-020-00564-5) contains supplementary material, which is available to authorized users.

The NaTi

The enormous volume expansion during cycling and poor electron conductivity of SnS2 limit its cycling stability and high rate capability. Herein, flower-like SnS2 anchored on 3D carbon nanofiber structures were designed and synthesized by a simple hydrothermal method. Pyrolyzed bacterial cellulose as 3D carbon nanofibers can not only offer a continuous pathway of Li+ and electrons, but can also migrate the serious volume change of SnS2 during charging and discharging. The obtained composite shows a specific capacity of 408.8 mA h g-1 even after 1500 cycles at 10 A g-1, and almost no specific capacity decay after 20 cycles with a retention of 97.5%.

Lithium–sulfur batteries are currently attracting wide interest due to their high theoretical capacity, although their energy density is greatly limited by the low tap density of traditional C/S cathode materials. Herein hollow VO2@S microspheres were designed as cathode materials with high volumetric capacity by combining the intercalation and conversion mechanisms. The hollow microsphere can offer enough space for high sulfur loading, which results in a high tap density of 1.64 g cm−3, while VO2 can offer additional capacity by Li intercalation reactions and has strong interactions with polysulfides to prevent the shuttling effect by its in situ surface sulfidation. Therefore, the obtained materials delivered a high volumetric capacity (1084 mA h cm−3 at 0.1C) and good rate capability and cycling performance (440 mA h g−1 at 1.0C after 200 cycles). This study demonstrates that traditional cathode materials with a proper potential window would be an alternative host for sulfur to offer additional capacity and increase the energy density due to their high tap density.

Silicon (Si) has been regarded as a promising next-generation anode material to replace carbon-based materials for lithium ion batteries (LIBs). However, the low initial coulombic efficiency and poor cycling stability limit its widespread application. With this in mind, carbon coated porous Si nanosheets (pSi@C) were prepared through the pyrolysis of C2H2 on porous Si nanosheets from air-oxidation demagnesiation of Mg2Si. Carbon coating improved the electrical conductivity of the composite, which is beneficial to the diffusion of Li+ and to maintain the structural integrity. The obtained pSi@C electrode shows a high initial coulombic efficiency of 80.3% and a reversible capacity of 2510 mA h g−1 at 0.4 A g−1. Furthermore, even at a current density of 2 A g−1, it can still show a reversible specific capacity of 1215 mA h g−1 after 200 cycles.

Metallic 1T layered disulfides ultrathin layers fabricated by the chemical exfoliation of 2H bulk via “top-down” method are highly attractive for energy storage because of their special metallic characteristics. However, the spontaneous transformation of 1T phase to the thermodynamically stable 2H phase is detrimental to electrochemical performance. In contrast to alkali metals, transition metals can efficiently stabilize 1T layered disulfides due to their stronger ionic potential and polarizability. Herein, Co stabilized metallic 1T MoS 2 monolayers with largely distorted structure (1T d Co MoS 2 ) are designed and synthesized via a “bottom-up” method, in which Co exists on the surface of S Mo S monolayers via Co S bonds, rather than substituting Mo. Its unique structure endows the improved thermal stability and higher conductivity over pristine 1T MoS 2 , and the obtained materials exhibit an enhanced specific capacitance of 454 F g −1 (∼100 F g −1 of pristine 1T MoS 2 ) at 0.5 A g −1 and a long cyclic stability with the capacitance retention of approximately 100% even after 25,000 cycles at 10 A g −1 .

Layered transition metal dichalcogenides are promising as lithium and/or sodium storage materials for lithium and sodium (Li/Na) ion batteries. However they always exhibit limited rate capability and long-term cycling stability, due to the fact that their 2D structures are easily restacking and agglomeration during cycling process and further result poor electrochemical reversibility. Herein, hierarchical Co1/3Mo2/3S2/graphene nanocomposites without CoSx and MoS2 impurities have been synthesized via one-pot solvothermal process. The incorporation of Co into MoS2 at atomic level can not only give rise to thinner and smaller nanosheets in the nanocomposites than MoS2/graphene nanocomposites, but also significantly decrease the size of in-situ formed MoS2/CoSx nanoparticles during electrochemical conversion process, which can greatly promoting the ion diffusion and suppressing the aggregation of active materials. Furthermore, the conductivity of Co1/3Mo2/3S2/graphene nanocomposites can be enhanced from 0.46 S m−1 (MoS2/graphene) to 1.39 S m−1 via changing the semiconducting MoS2 to metallic Co1/3Mo2/3S2. The simultaneously optimized electron conductivity and ions diffusion dynamics of Co1/3Mo2/3S2/graphene nanocomposites can effectively improve the reversibility of electrochemical conversion reactions. A capacity of 940 mAh g−1 and 529 mAh g−1 can be maintained at 3200th cycle (2 A g−1) in lithium-ion batteries and 200th cycle (1 A g−1) in sodium-ion batteries, respectively.

Silicon is regarded as a promising next-generation anode material to replace carbon-based materials in lithium–ion batteries. However, the poor conductivity and dramatic volume changes of Si anode materials lead to their low initial coulombic efficiency and unsatisfactory cycling stability. Herein, highly crystalline B-doped porous Si (B-doped pSi) nanoplates were designed and prepared via the air-oxidation demagnesiation of Mg2Si from p-type Si wafers. Doping with B greatly decreased the resistance and surface oxidation compared to the raw materials, and the high-temperature synthetic process resulted in high crystallinity. As a result, the obtained material exhibits a high initial coulombic efficiency of 89% and a superior rate capability of 1107 mA h g−1 at 6.4 A g−1. Furthermore, the unique porous plate-like structure provides free space for the volumetric expansion of Si, which results in good cycling performance (reversible capacity of 1500 mA h g−1 at 2 A g−1 after 300 cycles) in the B-doped porous Si.

Fe3C nanoparticles encapsulated in 3D porous graphite frameworks are fabricated via a cost-effective and scalable in situ salt template method. Thanks to the highly graphitic protecting layer on Fe3C nanoparticles and the 3D porous frameworks, the obtained materials exhibit excellent long-term durability and comparable electrocatalytic oxygen evolution activity with the state-of-the-art RuO2 catalyst.

The rate capability of battery-type anode materials has become a great limitation to the energy and power densities of lithium-ion capacitors. Besides the electronic conductivity, it is crucial to enhance the electrochemical rate by facilitating the diffusion and transportation of Li+. Herein, a new kind of porous Si@C ball-in-ball hollow structure was designed to build a stable electrode–electrolyte interface, overcome the volume change of Si and enhance the mass diffusion and conductivity simultaneously. The obtained porous Si@C ball-in-ball hollow spheres as Si anodes show great cycling stability for 1000 cycles and good rate capability with 943 and 586 mA h g−1 at 16.0 and 32.0 A g−1, respectively. As a result, lithium-ion capacitors based on porous Si@C ball-in-ball hollow spheres as anode materials give high energy densities of 239 and 154 W h kg−1 at the power densities of 1376 and ∼69 600 W kg−1, respectively. Furthermore, the lithium-ion capacitors also show a stable cycling performance for 15 000 cycles at 6.4 A g−1.

Photovoltaic modules are considered as the most efficient way to utilize solar energy, while the power conversion efficiencies of commercial crystalline silicon (c-Si) solar cells still need to be improved. Herein, nano-graphite was designed as a highly efficient electron transport layer in high performance ZnO/Si solar cells and prepared via a simple solution phase deposition and rapid annealing process. The ZnO QDs can broaden the range of spectral response by generating more electron–hole pairs via multiple exciton effects. The built-in-field formed between the n-type ZnO QD layer and n-type Si and highly conductive nano-graphite can accelerate the electron collection and transportation from n-type Si to the front electrode. Thus, the designed Si solar cell with nano-graphite and ZnO QD layers shows a significantly improved power conversion efficiency of 14.99% compared to the ZnO/Si solar cell (13.62%) and unmodified commercial c-Si solar cells (12.73%). This cost effective and environmentally friendly technology can be easily applied for the industrial scale production of Si solar cells.

Transition metal oxide nanomaterials have been applied in developing high capacity lithium ion batteries. However, transition metal oxide nanomaterials have some major issues to be addressed, including nanomaterials aggregation, severe side reactions and low conductivity. Herein, multiporous NiMnO3 micro-nano structure spheres are been synthesized, and their composites with graphene sheets (GNSs) have been prepared. The obtained multiporous NiMnO3 micro-nano structure graphene composites show excellent electrochemical performances with a high reversible capacity of 582 mA h g−1 at a current of 1 A g−1 after 150 cycles and 914 mA h g−1 at a current of 0.1 A g−1 after 50 cycles without obvious side reaction. The result shows the multiporous NiMnO3-GNSs micro-nano structure spheres can alleviate the side reaction of electrolyte.