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Leveraging size effects, nanoparticles of metal-organic frameworks, nanoMOFs, have recently gained traction, amplifying their scopes in electrochemical sensing. However, their synthesis, especially under eco-friendly ambient conditions remains an unmet challenge. Herein, an ambient and fast secondary building unit (SBU)-assisted synthesis (SAS) route to afford a prototypal porphyrinic MOF, Fe-MOF-525 is introduced. Albeit the benign room temperature conditions, Fe-MOF-525(SAS) nanocrystallites obtained are of ≈30 nm size, relatively smaller than the ones conventional solvothermal methods elicit. Integrating Fe-MOF-525(SAS) as a thin film on a conductive indium tin oxide (ITO) surface affords Fe-MOF-525(SAS)/ITO, an electrochemical biosensor. Synergistic confluence of modular MOF composition, analyte-specific redox metalloporphyrin sites, and crystal downsizing contribute to its benchmark voltammetric uric acid (UA) sensing. Showcasing a wide linear range of UA detection with high sensitivity and low detection limit, this SAS strategy coalesces ambient condition synthesis and nanoparticle size control, paving a green way to advanced sensors.

The structure–activity relationship is a cornerstone topic in catalysis, which lays the foundation for the design and functionalization of catalytic materials. Of particular interest is the catalysis of the hydrogen evolution reaction (HER) by palladium (Pd), which is envisioned to play a major role in realizing a hydrogen-based economy. Interestingly, experimentalists observed excess heat generation in such systems, which became known as the debated “cold fusion” phenomenon. Despite the considerable attention on this report, more fundamental knowledge, such as the impact of the formation of bulk Pd hydrides on the nature of active sites and the HER activity, remains largely unexplored. In this work, classical electrochemical experiments performed on model Pd(hkl) surfaces, “noise” electrochemical scanning tunneling microscopy (n-EC-STM), and density functional theory are combined to elucidate the nature of active sites for the HER. Results reveal an activity trend following Pd(111) > Pd(110) > Pd(100) and that the forma?tion of subsurface hydride layers causes morphological changes and strain, which affect the HER activity and the nature of active sites. These findings provide significant insights into the role of subsurface hydride formation on the structure–activity relations toward the design of efficient Pd-based nanocatalysts for the HER.

Electrochemical sensors are indispensable in clinical diagnosis, biochemical detection and environmental monitoring, thanks to their ability to detect analytes in real‐time with direct electronic readout. However, electrochemical sensors are challenged by sensitivity—the need to detect low concentrations, and selectivity—to detect specific analytes in multicomponent systems. Herein, a porphyrinic metal‐organic framework (PP‐MOF), Mn‐PCN‐222 is deposited on a conductive indium tin oxide (ITO) surface. It affords Mn‐PCN‐222/ITO, a versatile voltammetric sensor able to detect redox‐active analytes such as inorganic ions, organic hazardous substances and pollutants, including nitroaromatics, phenolic and quinone‐hydroquinone toxins, heavy metal ions, biological species, as well as azo dyes. As a working electrode, the high surface area of Mn‐PCN‐222/ITO enables high currents, and therefore leverages highly sensitive analysis. The metalloporphyrin centre facilitates analyte‐specific redox catalysis to simultaneously detect more than one analyte in binary and ternary systems allowing for detection of a wide array of trace pollutants under real‐world conditions, most with high sensitivity., Integration of a porphyrinic metal–organic framework on a conductive indium tin oxide surface affords an electrochemical sensor, Mn‐PCN‐222/ITO. Thanks to detecting several inorganic ions, organic hazardous substances and pollutants, Mn‐PCN‐222/ITO demonstrates multifaceted sensing with low detection limits. Benchmark sensing performances are set not only across several single components, but also in the corresponding binary and ternary mixtures.

In this work, alkaline hydrogen evolution reaction (HER) processes of three typical nickel-based electrocatalysts [i. e., Ni, α-Ni(OH)

A new hybrid system mainly composed of a dye-sensitized solar cell (DSSC), a solar selective absorber (SSA) and an absorption heat transformer (AHT) is theoretically put forward to harness the long wavelength sunlight transmitted through the DSSC. The models of both DSSC and AHT are adopted from the current literature and the condition enables the AHT to involve in heat upgrading is obtained. The model validations of DSSC and AHT are conducted using experimental data. Mathematical expressions of power output and efficiency for the hybrid system are formulated by taking a variety of irreversible losses into account. The effectiveness of the hybrid system is justified and evaluated. Maximum power density (MPD) and maximum energy efficiency (MEE) of the integrated system are, respectively, 158.2 W m−2 and 16.3 %, having evidently improvement compared to that of a single DSSC. A variety of operating conditions and design parameters affecting the hybrid system performance are studied. Numerical calculation results show that the working temperature, photoelectron absorption coefficient of DSSC and total heat-transfer area of the AHT have positive effects on the hybrid system performance. There exists an optimum TiO2 thin film thickness to optimize the hybrid system performance. However, a greater Schottky barrier has negative influence on the hybrid system performance. The results obtained here may provide some guidance for designing such a practical hybrid system.

Integration of porphyrin based metal–organic frameworks (PP-MOFs) on a solid surface has emerged as a key advancement in terms of exploring their promising applications. However, a great challenge remains unmet when it comes to successfully fabricating a PP-MOF film with crystallinity, controllable orientation, adjustable morphology and thickness, all sustained in one. Herein, for the first time, vapor-assisted conversion (VAC) was developed as a facile and versatile technique to fabricate functional PP-MOF films on various substrates related to different application requirements. To understand the nucleation and growth mechanism, a number of fabrication methods were leveraged to prepare the PP-MOF films, thanks to an assortment of PP-MOFs varying from two-dimensional (2D) to three-dimensional (3D) scaffolds. The studies show that PP-MOF films are likely to display different nucleation and growth processes following different deposition approaches. This study demonstrates the pros and cons of different methods in the fabrication of functional PP-MOF films, potentially offering critical tools and reference points for the preparation of next-generation functional MOF thin films in general.

Understanding the electrode/electrolyte interface is crucial for optimizing electrocatalytic performances. Here, we demonstrate that the nature of alkali metal cations can profoundly impact the oxygen evolution activity of surface-mounted metal-organic framework (SURMOF) derived electrocatalysts, which are based on NiFe(OOH). In situ Raman spectroscopy results show that Raman shifts of the Ni-O bending vibration are inversely proportional to the mass activities from Cs

To harvest the relatively high wavelength sunlight, a novel hybrid system coupling a thermally regenerative electrochemical cycle to a dye-sensitized solar cell is proposed. Efficiencies and power outputs of dye-sensitized solar cell and thermally regenerative electrochemical cycle are calculated, and the mathematical relationship between the electric current of thermally regenerative electrochemical cycle and the working current density of dye-sensitized solar cell is deduced. The power output and efficiency of the hybrid system are also derived considering multiple irreversible losses. The feasibility and effectiveness of the proposed hybrid system will be assessed by comparing the performances between the hybrid system and the single dye-sensitized solar cell. Numerical calculations show that the maximum efficiency and power density of the hybrid system allow 32.04% and 32.18% greater than that of the single dye-sensitized solar cell, respectively. Comprehensive parametric studies are undertaken to examine the dependences of the hybrid system performance on some operating conditions and microstructure parameters, including electrode porosity, photoelectron absorption coefficient, Schottky barrier, film thickness and internal resistance of thermally regenerative electrochemical cycle. The derived results may offer new insights into design and optimization of such an actual hybrid system.

A new combined system consisting of a high-temperature proton exchange membrane fuel cell (HT-PEMFC), a regenerator and a thermoelectric generator (TEG) is developed. The mathematical relationship between the HT-PEMFC operating current density and the TEG dimensionless current is derived, and the operating current density range of HT-PEMFC in which the TEG allowed to work is determined. Power output and efficiency of the combined system are formulated under different operating conditions. Compared with the stand-alone HT-PEMFC, the proposed combined system allows the equivalent power density to increase by 21%. The optimum criteria and general performance characteristics for the complete system are specified. Moreover, the effects of the operating current density, doping level, relative humidity, operating temperature, heat conductivity and figure of merit of the thermoelectric materials on the combined system performance characteristics are revealed. The obtained results may provide some theoretical insights into the design and integration of such an actual combined system.

A combined system model consisting of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC), a regenerator and a thermoelectric generator (TEG) is proposed, where the TEG is applied to harness the generated waste heat in the HT-PEMFC for extra electricity production. The TEG considers not only the Seebeck effect and Peltier effect but also the Thomson effect. The mathematical expressions of power output, energy efficiency, exergy destruction rate and exergy efficiency for the proposed system are derived. The energetic and exergetic performance characteristics for the whole system are revealed. The optimum operating ranges for some key performance parameters of the combined system are determined using the maximum power density as the objective function. The combined system maximum power density and its corresponding energy efficiency and exergy efficiency allow 19.1%, 12.4% and 12.6% higher than that of a stand-alone HT-PEMFC, while the exergy destruction rate density is only increased by 8.6%. The system performances are compared between the TEG with and without the Thomson effect. Moreover, the impacts of comprehensive parameters on the system performance characteristics are discussed. The obtained results are helpful in developing and designing such an actual combined system for efficient and clean power production.

A novel solar assisted cogeneration system composed of a parabolic dish collector (PDC), a vacuum thermionic generator (VTIG), and an absorption refrigerator (APR) is proposed, in which the APR harvests the rejected heat from the VTIG for further cooling production. The equivalent power output and efficiency of the proposed system are obtained by considering various irreversible losses including radiation and convection heat losses of the PDC, radiation heat losses between the cathode and anode of the VTIG, heat transfer irreversibility, irreversible effects inside the working fluid of the APR. The maximum attainable efficiency increases from 17.21% to 27.06% as the bottoming APR is hybridized into the system. Meanwhile, the corresponding power density gains a 13.47% increase. Comprehensive sensitivity analyses are conducted to examine the dependence of the proposed system performance on some decisive design parameters and operating conditions such as absorber temperature of the solar collector, solar concentration ratio, solar irradiance, work function and anodic temperature of the VTIG, heat transfer area, heat transfer coefficient, and internal irreversibility factor of APR. The obtained results may provide some new insights into development and operation of such a solar powered cogeneration system.

Magnetic field may distort neutron stars (NSs), but its effect has not been robustly tested through gravitational-wave observation yet due to the absence of a fast rotating Galactic magnetar. Part of gamma-ray bursts (GRBs) are potential to investigate the magnetically-induced distortion since their central objects may be millisecond magnetars. In this paper, we propose a method to estimate the distortions of these possible magnetars under GRB magnetar scenario. According to the case study of GRB 070521, we find a relation between the effective magnetically-induced ellipticity, $\epsilon_{\rm B,eff}$, and the effective dipole magnetic field strength on NS surfaces, $B_{\rm eff}$, namely $\epsilon_{\rm B,eff}\sim 10^{-3}(B_{\rm eff}/10^{15}\rm G)^{2}$. Furthermore, we constrain the internal magnetic-field structure of the magnetar to be $B_{\rm eff}\sim 0.02 $ and $B_{\rm eff}\sim 0.1B_{\rm t}$, where $$ is the volume-averaged internal toroidal field. The constraint may be used as the initial condition in modeling the structure of NS magnetospheres. At last, the possibility of testing the method shown in this paper through gravitational-wave observations is discussed., Comment: 6 pages, 4 figures, A&A accepted

Advanced materials 33(38), 2103218 (2021). doi:10.1002/adma.202103218, Materials derived from surface-mounted metal���organic frameworks (SURMOFs) are promising electrocatalysts for the oxygen evolution reaction (OER). A series of mixed-metal, heterostructured SURMOFs is fabricated by the facile layer-by-layer deposition method. The obtained materials reveal record-high electrocatalyst mass activities of ���2.90 kA g$^{���1}$ at an overpotential of 300 mV in 0.1 m KOH, superior to the benchmarking precious and nonprecious metal electrocatalysts. This property is assigned to the particular in situ self-reconstruction and self-activation of the SURMOFs during the immersion and the electrochemical treatment in alkaline aqueous electrolytes, which allows for the generation of NiFe (oxy)hydroxide electrocatalyst materials of specific morphology and microstructure., Published by Wiley-VCH, Weinheim

The combination of dimethyl sulfoxide (DMSO)-solvent doping and physical–chemical DMSO/salt de-doping in a sequence has been used to improve the thermoelectric (TE) properties of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) films. A high power factor of ca.105.2 µW m−1 K−2 has been achieved for the PEDOT:PSS film after post-treatment with 10 % sodium sulfite (Na2SO3) in the DMSO/salt mixture (v/v), outperforming sodium bicarbonate (NaHCO3). The initial DMSO-doping treatment induces a distinct phase separation by facilitating the aggregation of the PEDOT molecules. At the same time, the subsequent DMSO/salt de-doping post-treatment strengthens the selective removal of the surplus non-conductive PSS chains. Substantial alterations in the oxidation level, chain conformations, PEDOT crystallites and their preferential orientation are observed upon treatment on the molecular level. At the mesoscale level, the purification and densification of PEDOT-rich domains enable the realization of inter-grain coupling by the formation of the electronically well-percolated network. Thereby, both electrical conductivity and Seebeck coefficient are optimized.

A new hybrid system model comprised of a concentrated photovoltaic cell (CPC) and an elastocaloric cooler (ECC) is proposed, where the ECC is driven by the thermal energy from CPC that cannot be converted into electrical energy. Mathematical expression between the exhaust heat of CPC and the operating electric current as well as the time required for one cycle are derived. Mathematical formulas for the power output and efficiency of CPC and proposed system and the cooling rate and efficiency of ECC are specified. Calculations show that maximum energy efficiency (MEE) and maximum power density (MPD) of hybrid system are, respectively, 20.20 % and 767.47 W m−2 larger than that of the CPC alone. A variety of design parameters and operating conditions affecting the hybrid system performance are studied. Numerical calculation results show that the environmental temperature, solar irradiation, concentration ratio and cross-sectional area ratio of CPC as well as length ratio are helpful to improve the hybrid system performance. The results obtained are helpful to optimally design and run such a real CPC/ECC hybrid system.

In addition to generate electricity, proton exchange membrane fuel cells (PEMFCs) also produce a considerable quantity of waste heat, which may affect the cell normal operation if not removed immediately. To remove and harvest the waste heat, a novel combined system that couples an elastocaloric cooler (ECC) to a PEMFC is proposed, where the ECC harnesses the waste heat from the PEMFC for cooling purposes. Including thermodynamic and electrochemical irreversible losses, mathematical expressions for efficiency and power output of the combined system are obtained. The operating current density region of the PEMFC allowing the ECC to work is determined and the optimum operation regions for power output and efficiency of the combined system are specified. Moreover, numerical calculations indicate that the equivalent maximum power density and its corresponding efficiency of the combined system can be, respectively, increased by 163.2 % and 64.2 % in comparison with that of the single PEMFC. Exhaustive parametric studies are further undertaken to reveal how the combined system performance is associated with some key design parameters and operation conditions, such as operating temperature, operating pressure, proton exchange membrane thickness, environment temperature, cross-sectional area ratio, length ratio and thermodynamic losses related parameters. The results may offer some theoretical bases for designing and running such a real combined system and open up a new avenue to harvest waste heat from PEMFCs.

Transition metal oxides-based electrode materials are currently under intensive research as anode candidates for next-generation lithium-ion batteries (LIBs) due to their environmental benignity, high capacity and natural abundance. Unfortunately, the intrinsically low conductivity and large structure change of metal oxide electrodes lead to their phase segregation and serious capacity decay, which severely restrict their practical application. In this work, we designed and fabricated a unique flower-like hybrid with Co3O4 nanoparticles decorated on nitrogen-doped carbon sheets (Co3O4/NC) through a combined carbonization and oxidation approach using novel cobalt-based metal-organic frameworks (MOFs) as precursor. The in-situ synthesis of Co3O4/NC from MOFs improves the combination between Co3O4 nanoparticles and nitrogen-doped carbonaceous substrate, ensures high structure stability and facilitates the electron and ion transport upon cycling. The as-synthesized Co3O4/NC exhibits a remarkable lithium storage performance with high reversible capacity (1145.1 mAh g−1 after 100 cycles at 0.1 A g−1), superior rate capability (498.8 mAh g−1 at 4 A g−1) and excellent long-term cycling stability (797.5 mAh g−1 at 0.5 A g−1 and 671.1 mAh g−1 at 1 A g−1 after 500 cycles), which outperforms those of most of Co3O4-based electrodes reported so far.

Hollow nanostructures are favorable for electrode materials to enhance their energy storage performance due to their unique structural features. In this work, hollow bimetallic phosphide (NixCo1-xP) was fabricated via etching treatment of ZIF-67 and further phosphorization. The as-obtained NixCo1-xP composites display a high specific capacity of 548 C g−1 at 1 A g−1 in 2 M KOH aqueous solution, excellent rate capability (83.7%, 77.6%, 71.7% and 66.2% capacity retention at 10, 20, 30 and 40 A g−1), and remarkable cycling stability (86% capacity retention at 7 A g−1 after 3000 cycles). Furthermore, a hybrid supercapacitor, constructed by NixCo1-xP as anode and active carbon as cathode, exhibits excellent specific capacitance (115.8 F g−1 at 1 A g−1), high gravimetric energy/power density (31.52 Wh kg−1 at 700 W kg−1), and outstanding long-term cycling stability (98.3% capacitance retention even after 10000 cycles). The excellent electrochemical performance should be attributed to the good interfacial contact between electrode and electrolyte, unique hollow structure with suitable surface area and good electrical conductivity of NixCo1-xP. The results suggest a great potential of NixCo1-xP composites in electrochemical energy storage devices.

Currently carbon nanofibers are attracting myriad interest for supercapacitors due to their high specific capacitance and low cost. However, their poor electrical conductivity and microporous structure restrict their wide applications. Here, flexible micro-/mesoporous carbon nanofibers embedded with ordered carbon (MCNF) were prepared by coaxial electrospinning and subsequent corrosion. Field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction spectroscopy and nitrogen adsorption-desorption isotherm were used to characterize their morphology, structure and specific surface area. Electrochemical tests of cyclic voltammetry and electrochemical impedance spectroscopy show that the specific capacitance of MCNF can reach 272 F g−1 at 1 A g−1, much higher than that of carbon nanofibers (216 F g−1) which is obtained by single axial electrospinning. The flexible symmetrical supercapacitor based on MCNF electrodes exhibits an excellent electrochemical performance, with a capacitance retention of 96.7% after 3000 charge-discharge cycles and a high energy density of 11.1 Wh kg−1 when the power density is 0.25 kW kg−1. More interestingly, its specific capacitance almost does not change even when it is bent to 135°. The results show that MCNF is a promising electrode material for flexible supercapacitors.

A novel system combining photocatalysis and capacitive deionization (CDI) was proposed and used to efficiently remove the total Cr from the aqueous solution for the first time. MIL-53(Fe) with wide visible-light absorption was successfully prepared by a simple solvothermal method, and applied as positive photoelectrode material of the photocatalysis-CDI system (PCS) to convert Cr(VI) to Cr(III). Active carbon was used as negative electrode material to absorb Cr(III). An enhanced removal of Cr(VI) can be obtained by applying visible light irradiation and 1.3 V direct current (DC) voltage simultaneously and the Cr(VI) removal can reach a maximum value of 81.6%, much higher than those under individual 1.3 V DC voltage (39.4%) or visible light irradiation (54.2%), demonstrating the synergistic effect from CDI and photocatalysis. More importantly, effective removal of the total Cr with high removal ratio (72.2%) can be achieved, which is difficult to be realized using current other technologies. The strategy in this work provides a promising method for the complete removal of high-valence heavy metal ions.

Smart design and rational fabrication of novel anode materials with high specific capacity and long cycling stability are of significant importance for high-performance lithium-ion batteries (LIBs). Herein, nanostructured ZnO/NiO microspheres with a nanorods-composed shell and a microsphere yolk were synthesized by a controlled calcination treatment of the bimetallic organic frameworks in air. The obtained yolk-shell ZnO/NiO microspheres are observed to have an average diameter of 2 μm with uniform microsphere morphology from field-emission scanning electron microscopy and high-resolution transmission electron microscopy. Benefitting from the unique yolk-shell structure inherited from the bimetallic organic frameworks and the synergistic effect from ZnO and NiO, the as-prepared yolk-shell ZnO/NiO displays excellent lithium storage performance, including high specific capacity (1008.6 mAh g−1 at 0.1 A g−1 after 200 cycles), superior rate capability (437.1 mAh g−1 at 2 A g−1) and outstanding long-term cycling stability (592.4 mAh g−1 at 0.5 A g−1 after 1000 cycles), which demonstrates its promising potential as high-performance anode material for LIBs.

Nickel sulfide, a promising anode for sodium-ion batteries (SIBs), has drawn a lot of attention due to its natural abundance, low cost, rich types and high theoretical specific capacity (Ni3S2: 446, NiS: 591 and NiS2: 879 mA h g−1). However, the huge volume change induced severe electrode pulverization results in the low specific capacity and poor cycling stability of nickel sulfide electrodes. Herein, in this paper, we developed a metal–organic framework (MOF) strategy to prepare pomegranate-like clusters with small NiS2 nanoparticles anchored on nitrogen doped porous graphitic carbon networks (NiS2/NC) via successive carbonization and sulfidation. When evaluated as an anode for SIBs, the as-prepared NiS2/NC hybrid exhibited a high reversible capacity of 505.7 mA h g−1 after 100 cycles at 0.1 A g−1, excellent rate capability (294.4 mA h g−1 at 3 A g−1) and robust cycling stability with a capacity of 356.2 mA h g−1 after 300 cycles at 0.5 A g−1, which outperforms most of the nickel sulfide based electrodes reported so far. The excellent cycling performance and rate capability for SIBs can be attributed to the unique structure inherited from nickel based MOFs, in situ fabrication strategy, high capacity of NiS2, and conductive and buffering features of the nitrogen-doped graphitic carbon networks, demonstrating the great potential of the as-prepared NiS2/NC hybrid for high-performance SIBs.

TiO2 is now developed as a low-cost and high-safety anode material for sodium-ion batteries (SIBs), but its low sodium ion diffusion ability and poor electrical conductivity hinder its sodium-storage performance. In this work, TiO2 nanocrystals embedded in sulfur-doped porous carbon (TSPC) were synthesized through the solvothermal synthesis of a metal–organic framework MIL-125(Ti) precursor and subsequent pyrolysis with inorganic sulfur powder under a nitrogen atmosphere. The inner TiO2 nanocrystals enlarge the electrode/electrolyte interface and shorten the diffusion distance of sodium ions, while the sulfur-doped porous carbon enhances the electron transport ability, inhibits the aggregation of TiO2 nanocrystals, and offers more reaction sites for sodium storage. Benefiting from the synergetic effects between TiO2 nanocrystals and sulfur-doped porous carbon, when used as the anode material for SIBs, the TSPC demonstrates an ultrahigh specific capacity of 323 mA h g−1 after 100 cycles at 50 mA g−1 and extraordinary cycling stability with a capacity retention of 80.1% after 1500 cycles. The TSPC should be a promising anode material for high-performance SIBs.

The sodium storage performance of recently reported Ti3C2Tx MXenes is seriously restricted by their low specific capacity due to their insufficient interlayer spacing. Herein, for the first time, a sulfur (S) doped multilayered Ti3C2Tx MXene was prepared by a simple sulfidation treatment of Ti3C2Tx using thiourea as the S source, which shows an increased interlayer spacing and enhanced electrical conductivity. When used as an anode for sodium-ion batteries (SIBs), the S-doped Ti3C2Tx exhibits a high reversible capacity of 183.2 mA h g−1 after 100 cycles at 0.1 A g−1, excellent rate capability (121.3 mA h g−1 at 2 A g−1 and 113.9 mA h g−1 at 4 A g−1) and robust long-term cycling stability with a reversible capacity of 138.2 mA h g−1 after 2000 cycles at 0.5 A g−1. Notably, the superior sodium storage performance should be attributed to the multilayered morphology, expanded interlayer spacing and enhanced electrical conductivity as well as the high contribution of surface-induced capacitive behavior after S doping, and it outperforms those of reported Ti3C2Tx based electrodes, highlighting the feasibility of the S doping strategy. Most importantly, this work offers a novel approach for smart design and rational fabrication of heteroatom-doped MXenes for energy storage and conversion applications.

For the first time, N,B dual-doped porous carbon spheres (denoted as PCSs) were prepared through direct carbonization of covalent organic frameworks (COFs) and used as an electrode material for membrane capacitive deionization (MCDI). Due to their high accessible surface area and defect-abundant structure offered by N,B-co-doping, the nanostructured PCSs exhibit high desalination ability and are expected to be promisingly applied in MCDI.

Photovoltaic cells only can convert a small part of the inlet sunlight into electricity, and the rest part of the sunlight is transformed into heat. The accumulated heat may significantly degrade the photovoltaic cell performance if not removed in time. In this work, a coupling system model composed of a dye-sensitized solar cell (DSSC), a solar selective absorber (SSA) and a flexible annular thermoelectric generator (ATEG) is put forward to broadbandly harvest the inlet sunlight, in which the ATEG simultaneously considers the Thomson effect, Peltier effect and Seebeck effect. Including various irreversible losses in the coupling system, performance indicators for DSSC, ATEG and coupling system are analytically formulated, from which the energy and exergy performance are revealed. The maximum power density, maximum energy and exergy efficiencies of the coupling system can be, respectively, 86.01 W m−2, 29.56% and 31.77%, which are, respectively, 10.52%, 39.24% and 10.54% higher than that of the single DSSC. Numerical calculation results indicate that the Schottky barrier height, thickness of the TiO2 mesoporous oxide, number of ATEGs, annular shape parameter of ATEG, thickness and width of ATEG can be optimized to maximize the power density, energy and exergy efficiencies. Besides, it reveals that the Thomson effect worsens the coupling system performance. The results obtained are helpful to design and run such a real DSSC-ATEG coupling system.

Increasingly, climate neutrality is becoming a consensus among many countries. While this can motivate toward higher proportions of renewable energy, it can also result in significant increases in the volatility of power systems. Concentrating solar power (CSP) combines the features of zero-emissions and dispatching capability, rendering it an ideal technology for sustainable power systems. In comparison with other clean energy generation technologies, CSP remains expensive with a levelized cost of energy (LCOE) of 0.184 $/kWh in 2018. However, in addition to LCOE, the benefits of integrating CSP for the entire power system are worth considering for a liberalized electricity market. This paper presents the development of a multistage stochastic programming model, in which the uncertainty of variable renewable energy is indicated by a modified scenario tree approach. A case study is demonstrated based on three provinces in China with different generation structures. The results demonstrate the economic value of CSP integration, which increases its investment potential—especially when combined with more variable renewables.

Manganese oxide (MnOx)-based materials are widely utilized in the field of electrocatalysis as bifunctional electrocatalysts for the oxygen reduction and evolution reactions. However, for an accurate assessment of their performance, the determination of their electrochemical active surface area (ECSA) is of paramount importance. So far, there is no fast and reproducible methodology. This article presents an easily applicable and affordable technique to determine the ECSA of MnOx accurately. The presented methodology makes use of the specific adsorption capacitance of reaction intermediates close to the onset potential of the oxygen evolution reaction. The electrochemical impedance spectroscopy is utilized to measure the specific adsorption capacitances at different potentials. Using MnOx thin-film electrodes, we determine the specific adsorption capacitances and present calibration values, which can be used for an accurate determination of the ECSA of different, for instance, nanostructured materials.

Metal–organic frameworks (MOFs) with high porosity and a regular porous structure have emerged as a promising electrode material for supercapacitors, but their poor electrical conductivity limits their utilization efficiency and capacitive performance. To increase the overall electrical conductivity as well as the efficiency of MOF particles, three-dimensional networked MOFs are developed via using preprepared conductive polypyrrole (PPy) tubes as the support for in situ growth of MOF particles. As a result, the highly conductive PPy tubes that run through the MOF particles not only increase the electron transfer between MOF particles and maintain the high effective porosity of the MOFs but also endow the MOFs with flexibility. Promoted by such elaborately designed MOF–PPy networks, the specific capacitance of MOF particles has been increased from 99.2 F g–1 for pristine zeolitic imidazolate framework (ZIF)-67 to 597.6 F g–1 for ZIF–PPy networks, indicating the importance of the design of the ZIF–PPy cont...

In this work, porous NiO microspheres interconnected by carbon nanotubes (NiO/CNTs) were successfully fabricated by the pyrolysis of nickel metal-organic framework precursors with CNTs and evaluated as anode materials for lithium-ion batteries (LIBs). The structures, morphologies, and electrochemical performances of the samples were characterized by X-ray diffraction, N2 adsorption-desorption, field emission scanning electron microscopy, cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy, respectively. The results show that the introduction of CNTs can improve the lithium-ion storage performance of NiO/CNT composites. Especially, NiO/CNTs-10 exhibits the highest reversible capacity of 812 mAh g−1 at 100 mA g−1 after 100 cycles. Even cycled at 2 A g−1, it still maintains a stable capacity of 502 mAh g−1 after 300 cycles. The excellent electrochemical performance of NiO/CNT composites should be attributed to the formation of 3D conductive network structure with porous NiO microspheres linked by CNTs, which benefits the electron transfer ability and the buffering of the volume expansion during the cycling process.

Novel Sb2S3@multiwalledcarbonnanotubes(MWCNTs) (SM) composites were synthesized via a facile and green method which included an in-situ growth of Sb2S3 nanoparticles on the surface of MWCNTs through precipitation and subsequent thermal treatment. The morphologies and structures of SM composites were tested by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and nitrogen adsorption and desorption isotherms. Finally, their application as anode materials for sodium-ion batteries (SIBs) was investigated through corresponding electrochemical measurements such as galvanostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the SM composites display higher capacity, better cycling stability and superior rate performance than pure Sb2S3, and a capacity of 412.3 mAh g−1 after 50 cycles at 50 mA g−1 is obtained for SM composites with 30 wt.% MWCNTs loading. The enhanced performance is ascribed to an increase in the specific surface area, an improvement in the charge transfer and effective buffering of the volume change offered by the porous conductive network structure of the composite with the introduction of MWCNTs.

Rational fabrication and structure design of anode materials with high specific capacity and excellent cycling stability are of significant importance for the development of high-performance lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). In this paper, a zeolitic imidazolate framework-8 (ZIF-8) with a unique polyhedral morphology and large size (about 2 μm) was successfully synthesized through a facile co-precipitation method. After successive carbonization and sulfidation, ZnS nanoparticles decorated on nitrogen-doped porous carbon polyhedra (ZnS/NPC) were obtained. When applied as the anode material for LIBs, the ZnS/NPC hybrid displays the highest reversible specific capacity for ZnS-based electrodes reported so far (1067.4 mA h g−1 at 0.1 A g−1 after 200 cycles), excellent rate capability (364.6 mA h g−1 at 4 A g−1), and robust long-term cycling performance (856.8 mA h g−1 at 1 A g−1 after 1000 cycles). As for SIBs, the resultant ZnS/NPC also exhibits a desirable capacity of 370.6 mA h g−1 after 100 cycles at 0.1 A g−1 and 289.2 mA h g−1 after 1000 cycles at 1 A g−1. Such superior lithium and sodium storage performances should be attributed to the distinctive structure advantages inherited from ZIF-8, where the Zn ions were in situ converted to ZnS with high reactivity upon electrochemical cycling and the organic linkers were pyrolyzed to nitrogen-doped porous carbon polyhedra to enhance the conductivity of the hybrid and keep the structure stability during cycling.

Transition metal phosphides, especially Ni2P, are of great interest as promising battery-type electrode materials for hybrid supercapacitors, but their poor electrical conductivity and porosity limit their application. Here, for the first time, the synthesis of carbon-incorporated Janus-type Ni2P/Ni hollow spheres (Ni2P/Ni/C) was reported via simultaneous carbonization and phosphorization of Ni-based metal–organic frameworks (Ni-MOFs). Their unique structural merits include the incorporated carbon content, Janus-type Ni2P/Ni nanocrystals, and high-porosity hollow structure, thus endowing them with a high specific surface area, good electrical conductivity and low density. As a result, the optimized Ni2P/Ni/C exhibits a remarkable specific capacitance of 1449 F g−1 at 1 A g−1 in 2 M KOH aqueous electrolyte in a three-electrode system. A hybrid supercapacitor device was fabricated by using Ni2P/Ni/C as the positive electrode and active carbon as the negative electrode, and it achieves a very high energy density of 32.02 W h kg−1 at a power density of 700 W kg−1 and a remarkable cycling stability (about 99% capacitance retention after 5000 cycles). The Ni2P/Ni/C should be one of the most promising electrode materials for hybrid supercapacitor application.

Here, ultrathin nitrogen-doped carbon/graphene nano-sandwiches were synthesized by carbonization of graphene oxide-based nanosheets, which were fully covered with ultrasmall ZIF-8 nanocrystals. The novel sandwich structure possesses large accessible surface area, excellent electrical conductivity, and high nitrogen content, thus showing superior desalination performance.

Metal–organic frameworks (MOFs) and their derivatives are considered as promising catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which are important for many energy provision technologies, such as electrolyzers, fuel cells and some types of advanced batteries. In this work, a “strain modulation” approach has been applied through the use of surface‐mounted NiFe‐MOFs in order to design an advanced bifunctional ORR/OER electrocatalyst. The material exhibits an excellent OER activity in alkaline media, reaching an industrially relevant current density of 200 mA cm−2 at an overpotential of only ≈210 mV. It demonstrates operational long‐term stability even at a high current density of 500 mA cm−2 and exhibits the so far narrowest “overpotential window” ΔE ORR‐OER of 0.69 V in 0.1 m KOH with a mass loading being two orders of magnitude lower than that of benchmark electrocatalysts., A simple strain approach was explored to prepare a NiFe‐based ORR/OER electrocatalyst derived from surface‐mounted metal–organic frameworks by rational introduction of functional groups into the organic linker. The catalyst exhibits an excellent OER activity, reaching industrially relevant current densities. As a bifunctional catalyst, it demonstrates a narrow overpotential window of ≈0.69 V in 0.1 m KOH, surpassing reported state‐of‐the‐art systems.