BiO1−xCl with optimum surface oxygen vacancies modulate the surface spatial electron structure and local electric field, and thus substantial photo-generated electrons were effectively ferry to the ...confined PMS by electron shuttles and hamper its random adsorption and disorder self-quenching. Ultimately, outstanding PMS utilization rate and pollutant removal rate was obtained.
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•BiO1−xCl with optimum surface oxygen vacancies was prepared.•Surface oxygen vacancies confine activation PMS.•Surface oxygen vacancies halted the self-quenching of active species population.•Surface oxygen vacancies significantly boosted PMS utilization rate.
Hinder self-quenching of active species and augment peroxymonosulfate (PMS) utilization rate is a challenging for advanced oxidation processes (AOPs). Therefore, BiO1−xCl with appropriate surface oxygen vacancies (SOVs) was fabricated by microwave reduction method. Experimental results reflect that BOC-2 can remediate 79.4 % doxycycline hydrochloride (50 mg L−1) in 1.75 h under the constantly yield active species population (ASP). Simultaneously, theoretical calculation discerns that reasonable SOVs can increase PMS adsorption energy, change PMS adsorption configuration and peroxy bond length. Thus, photo-induced electrons can fast ferry to the confined PMS via electron shuttles formed by SOVs to activate PMS. Ultimately, ASP self-quenching was halted and PMS utilization rate was ameliorated. Furthermore, the structure–activity relationship between SOVs and PMS utilization rate was established and the environmental toxicity of the intermediates was evaluated. This work offers an ingenious strategy to steer PMS activating behavior and boost its utilization rate by defect engineering.
The structural stability of electrode materials is the crux of significantly improve the electrochemical performance of pseudocapacitor electrodes. Herein, we demonstrate the preparation of NiCo2S4 ...with core-shell and micro-porous structure on nickel foam as an efficient anode material for asymmetric supercapacitor (ASC) via hydrothermal and co-sulfurization processes. The NiCo2S4 electrode shows a remarkable specific capacitance of 850.2 C g−1 at 1 A g−1, and retains 93.6 % original capacitance after 5000 cycles. Furthermore, the NiCo2S4 electrode also have excellent electrochemical performance when used as an anode of asymmetric NiCo2S4//Active Carbon (AC) supercapacitor, which generates an energy density as 38.1Wh Kg−1 at 700 W kg−1 and 84.3% capacity retention after 5000 cycles. This work provide an efficiently method to suppress volume expansion during sulfuration reaction by core-shell structure, which potential application in transition metal sulfides electrode materials in electrochemical energy storage and conversion devices.
•Novel monodispersed graphene nanosheet constructed 3D porous structure is developed.•FeS2/FeS heteronanoparticles are firmly confined in the wrinkles of rGO nanosheets.•Rate capacity retention of ...53% is achieved at ultrahigh current density of 20 A g−1.•The material shows nearly decay-free cycling ability and high capacity (513 mAh g−1).
Metal sulfides/graphene hybrid nanomaterials have drawn tremendous research interest for developing high-performance electrodes of sodium-ion batteries. Nevertheless, the rate performance still should be addressed due to the propensity to π-π stacking between graphene nanosheets. In this work, we develop a hybridized 3D network material configuration which is constructed by interconnected monodispersed graphene nanosheets (MGNs) with confined FeS2/FeS hetero-nanoparticles (NPs) as the main active matter through a facile cold quenching-gas phase sulfidation technology. Benefiting from the distinctly wrinkled surface feature, the π-π restack between the graphene nanosheets is prevented, and meanwhile these MGN building blocks connect together by overlapping the edge regions to form a penetrative electrode framework with rich multiscale pores. Thus, the FeS2/FeS NPs@MGN hybrid electrode exhibits greatly enhanced Na-ion transport kinetics and excellent rate capability. Typically, under an ultrahigh current density of 20 A g−1, the reversible capacity of 251 mAh g−1 with high capacity retention of 52.7% still can be achieved. In addition, it is found the FeS2/FeS NPs are firmly confined in the wrinkles of the graphene nanosheets even after the repeated sodiation/disodiation processes, which contributes to the favorable structure stability and nearly decay-free cycling performance. A high discharge capacity of 513 mAh g−1 at 0.1 A g−1 is well maintained after 100 discharge/charge cycles due to the robust 3D graphene framework and the effective prevention of the active NPs from agglomeration and pulvaration by means of the confinement of graphene nanosheets. Furthermore, the superior confine effect on the suppression of polysulfide shuttling and the loss of active materials is also demonstrated.
An efficient and robust in situ surface-confined strategy was demonstrated for the fabrication of single-atom Fe-N4 on N-doped carbon nanoleaves (L-FeNC). Benefiting from abundant Fe-N4 active sites, ...enhanced mass and charge transfer, L-FeNC delivered superior performance for ORR and Zn-air battery to commercial Pt/C.
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•In situ surface-confined strategy was demonstrated to fabricate L-FeNC.•L-FeNC showed an E1/2 of 0.89 V and good stability for ORR in 0.1 M KOH.•High ORR performance is owing to abundant Fe-N4, favored mass and charge transfer.
Controllable fabrication of Fe-N-C based single-atom catalysts (SACs) for enhanced electrocatalytic performance is highly desirable but still challenging. Here, an in situ surface-confined strategy was demonstrated for the synthesis of single atomic Fe-N4 on N-doped carbon nanoleaves (L-FeNC). The in situ generated Zn3Fe(CN)62 could not only serve as a protection layer against collapse of nanoleaves but also provide abundant Fe source for the formation of Fe-N moieties during pyrolysis, leading to high surface area and high graphitization degree of L-FeNC simultaneously. Benefiting from abundant Fe-N4 active sites, enhanced mass and charge transfer, the as-prepared L-FeNC manifested a half-wave potential of 0.89 V for oxygen reduction reaction (ORR) in 0.1 M KOH. A maximum power density of 140 mW cm−2 and stable discharge voltage even after operation for 50,000 s have been demonstrated when the L-FeNC was used as air cathode for Zn-air battery. This work not only provided a unique surface-confined strategy for the synthesis of two-dimensional nanocarbons, but also demonstrated the significant benefit from rational design and engineering of Fe-N-C SACs, thus offering great opportunities for fabrication of efficient energy conversion and storage devices.
Il contributo illustra il progetto di pubblicazione su Wikidata dei dati bibliografici relativi allo spoglio dei contributi apparsi sulla rivista Ricerche di S/Confine. Vengono discussi le ragioni e ...gli obiettivi del progetto nel contesto applicativo dei Linked Open Data in ambito bibliografico e in particolare per l’editoria di ambito accademico.
Lithium-sulfur battery has been considered as the prospective competitive candidate for energy storage device, because of its huge advantages in specific capacity and energy density. Nevertheless, ...the application of lithium-sulfur battery is impeded by intrinsic polysulfide shuttle effect and poor electric conductivity of sulfur. To overcome these obstacles, hollow FePO4 spheres wrapped by reduced graphene oxide (FePO4@rGO) as efficient sulfur host material is synthesized. The hollow FePO4 spheres with large inner space are in favors of sulfur loading and buffer the volume expansion between S and discharge products (Li2S/Li2S2) during cycling process. Meanwhile, the hollow and polar FePO4 spheres afford synergy of physical confinement and chemical interaction to restrict polysulfides shuttle effect. Furthermore, the wrinkled rGO tightly-wrapped on the surface of FePO4 offers an interconnected conductive network. Profit from these merits, the FePO4@rGO as sulfur host manifests an impressive cycle stability with a low capacity decay rate of 0.037% per cycle at 0.5 C upon 1000 cycles, suggesting its enormous potential for high-performance Li–S battery.
•Hollow FePO4 spheres wrapped by rGO as sulfur host is synthesized.•Physical confinement and chemical adsorption of FePO4 suppress shuttle effect.•FePO4@rGO as sulfur host for the Li–S battery deliver prominent cycle stability.
The crystallization kinetics of supercooled Ag-In-Sb-Te liquids (in thick single film) has recently been shown to exhibit a fragile-to-strong crossover (FSC) behavior, which is beneficial to balance ...the contradiction between fast crystallization rate around the melting temperature (Tm) and good thermal stability (low crystallization rate) nearby the glass transition temperature (Tg). In this work, we fabricated an ultrathin Ag-In-Sb-Te film (∼7 nm) that is confined in a 2D structure. Does this confined ultrathin film exhibit FSC behavior? Focusing on this issue, we studied the crystallization features of 2D confined Ag-In-Sb-Te ultrathin film by using the method of ultrafast differential scanning calorimetry and the viscosity model of generalized Mauro-Yue-Ellison-Gupta-Allan. It was found that, the FSC behavior is presented and enhanced in this confined Ag-In-Sb-Te film. Interestingly, the FSC temperature of this confined Ag-In-Sb-Te is 473 K (∼1.25 Tg), which is equal to that of thick single Ag-In-Sb-Te film, indicating the structural origins of FSC behavior are same in these Ag-In-Sb-Te supercooled liquids, i.e., the FSC behavior stems from liquid-liquid phase transition that is predominantly caused by the increase of Peierls distortions with the competition between short range and medium range cluster. This reveals the crystallization features of ultrathin Ag-In-Sb-Te film, enabling a systematic optimization of the memory-switching kinetics in low-dimensional phase-change device.
•The crystallization kinetics of 2D confined AgInSbTe ultrathin film was studied by ultrafast DSC.•A distinct fragile-to-strong crossover kinetics feature was revealed in 2D confined ultrathin AgInSbTe film.•The mechanism of fragile-to-strong crossover in 2D confined ultrathin AgInSbTe film is same to that in single film.
•An experimental investigation on the SSRCFSST column is presented.•The research includes two tests of axial compression and eccentric compression.•The spiral stirrup can effectively improve the ...non-uniform confine.•A composite model confined by square steel tube and spiral stirrup is established.•The calculation formulas to estimate the bearing capacity are developed.
Stirrup-confined concrete-filled square steel tubular (CFSST) columns with spiral stirrup alleviates the local buckling of square steel tube, thereby improving both ultimate bearing capacity and ductility. This paper presents an experimental study on compressive behavior of spiral stirrup reinforced concrete-filled square steel tubular (SSRCFSST) columns. Twenty-nine axial compression specimens and eighteen eccentric compression specimens were tested for experimental investigation of the effects of the sample size, the concrete strength, the thickness of steel tube, the ratio of diameter to width, the spacing of spiral stirrup and the steel ratio. In addition, the effect of eccentricity ratio on the eccentric compression specimens was also investigated. The test results show that the spiral stirrup has excellent cooperation ability with square steel tube and concrete, can effectively improve the non-uniform confine of square steel tube and enhance the confine effect on concrete. Furthermore, decreasing the spacing of spiral stirrup can enhance the axial bearing capacity and ductility of SSRCFSST columns, but has little effect on the eccentric bearing capacity. A composite model confined by square steel tube and spiral stirrup is established, the calculation formulas to estimate the bearing capacity of SSRCFSST columns are developed and close correlations are found between the calculated results and the experimental results.
Transition metal sulfide/graphene-based composites show broad prospects as electrode materials for supercapacitors. To explore the energy storage mechanism of composites, and clarify the synergistic ...effect between transition metal sulfide and graphene, a series of composites have been synthesized by adjusting the addition of graphene oxide during the preparation of the composites. The results show that the addition of graphene can effectively inhibit the agglomeration of nickel-cobalt sulfide particles. Cyclic voltammetry revealed that the proportion of surface-controlled capacitance increases with the increase of graphene (from 64.04% to 89.01%). Graphene can significantly improve the capacitance and stability of composites, while exceed graphene degrades the properties of the composites. An asymmetric supercapacitor assembled with NC/rGO25S (adding 25 mg graphene oxide during material synthesis) and activated carbon (AC) provides high specific capacitance (199.3 F g −1 at 2 A g −1) and excellent cycle stability (maintaining 90.4% after 10 000 cycles at 10 A g −1). All in all, the mechanism exploration and performance optimization of NiCo2S4/rGO in this work are of great significance for the further development of nickel-cobalt sulfide/rGO materials.
•Confined growth of NiCo2S4 is achieved by adding appropriate amount of graphene during the synthesis of composites.•Revealing the synergies effects and separately capacitance contributions between nickle-cobalt sulfides and rGO.•Exploring the evolution of phase and morphology of the composite during material synthesis.•The nano-NiCo2S4/rGO with highly optimized performance is achieved and demonstrated in asymmetric supercapacitor.
