Blockchain possesses the potential of transforming global supply chain management. Gartner predicts that blockchain could be able to track $2 T of goods and services in their movement across the ...globe by 2023, and blockchain will be a more than $3 trillion business by 2030. Nowadays, a growing number of blockchain initiatives are disrupting traditional business models in each sector. In this paper, we provide a timely and holistic overview of the state-of-the-art, challenges, gaps and opportunities in global supply chain and trade operations for both the private sector and governmental agencies, by synthesising a wide range of resources from business leaders, global international organisations, leading supply chain consulting firms, research articles, trade magazines and conferences. We then identify collaborative schema and future research directions for industry, government, and academia to jointly work together in ensuring that the full potential of blockchain is unleashed amidst the socioeconomic, geopolitical and technological disruptions that global supply chains and trade are facing.
Herein, we reported an efficient and stable Z-scheme β-Bi2O3@g-C3N4 core/shell nanocomposite for photocatalytic degradation of recalcitrant antibiotic tetracycline.
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•The new ...β-Bi2O3@g-C3N4 core/shell nanocomposites were firstly fabricated.•The core/shell photocatalysts exhibited excellent photoactivity for TC degradation.•The enhanced photocatalytic mechanism is a Z-scheme charge transfer pathway.•The promising nanomaterials can be used for removal of antibiotic pollutants.
The elimination of recalcitrant pollutants from wastewater using core/shell structure photocatalysts has received much attention in the area of environmental science. In this study, novel β-Bi2O3@g-C3N4 core/shell nanocomposites were firstly fabricated via a feasible self-assembly methodology, in which β-Bi2O3 nanoparticles were chosen as the host material for g-C3N4 loading. The photocatalytic activity of the samples were evaluated by the degradation of antibiotic tetracycline (TC) under visible-light illumination (λ > 420 nm). Compared to the pristine β-Bi2O3 and g-C3N4, the prepared core/shell nanocomposites showed remarkably enhanced photocatalytic performance towards TC degradation in aqueous solution. Eventually, the 5 wt% g-C3N4 loaded core/shell sample (5%CN@BO) exhibited the optimum photocatalytic efficiency, and its rate constant (k = 0.0311 min−1) for TC degradation is much higher than lots of the previously reported photocatalysts. In addition, the as-synthesized 5%CN@BO also displayed excellent photostability for degradation of TC even after 5 times recycling tests. The highly visible-light-induced photoreactivity is ascribed to the formation of a core/shell Z-scheme heterojunction, which could significantly accelerate the separation of photoinduced electron-hole pairs and prolong the lifetime of charge carriers. This work provides an efficient core/shell nanomaterial for removal of antibiotic pollutants and will be useful for design of other core/shell photocatalysts.
Graphitic carbon nitride (g-C3N4) nanosheets with unique structural and electronic properties have received much attention in photocatalysis, yet the direct synthesis of ultrathin g-C3N4 is still a ...big challenge. Herein, high-performance g-C3N4 nanosheets were firstly prepared by directly thermal calcination of the hydrothermally pretreated melamine as precursor. Multiple techniques were carried out to characterize the as-prepared samples. Results shown that the morphologies, microstructures, and physicochemical properties of as-synthesized samples are strongly depended on the hydrothermal temperature. The desired g-C3N4 nanosheets with a thickness of around 3 nm could be synthesized through an optimized 200 °C hydrothermal pretreatment. Compared to the bulk g-C3N4, the ultrathin g-C3N4 nanosheets possessed high specific surface area, large electronic band structure, and fast photoinduced electron-hole separation capability. As a consequence, the resultant nanosheets exhibited excellent visible-light-driven photocatalytic water splitting performance for hydrogen evolution (503 μmol h−1 g−1), which is over 6 times higher than the bulk powder. This work highlights a feasible but simple strategy for the production of ultrathin graphite-like nanosheets and develops an efficient metal-free nanomaterial for application in energy conversion.
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Bismuth vanadate (BiVO4) with narrow bandgap was considered as one of the most desirable matrices for photoanode in photoelectrochemical (PEC) water splitting system. However, the poor charge ...separation in BiVO4 causes the practical PEC efficiency significantly lower than the theoretical value. Herein, we demonstrated an effective strategy for growing positively charged Co-MOF (ZIF-67) onto the surface of BiVO4 photoelectrode via the electrostatic attraction with negatively charged BiVO4. Then the Co-MOF-BiVO4 photoelectrodes were annealed and a uniform Co3O4 thin film was formed on the BiVO4 photoelectrode. Compared with the bare BiVO4 photoanode, the best photocurrent density of Co3O4/BiVO4 photoanode reached up to 2.35 mA/cm2 (1.23 V vs RHE), with an incident photon to current conversion efficiency (IPCE) of 26% (360 nm). The PEC hydrogen production of Co3O4/BiVO4 was 0.61 mmol/cm2 in 5 h (100 mW/cm2, 1.23 V vs RHE), which was almost 3.2 times higher than that of bare BiVO4. The significant enhancement of PEC performance over Co3O4/BiVO4 photoanodes could be attributed to the unique structure characteristics of the in-situ MOF-derived Co3O4 thin film, with extend surface area and increased number of active sites.
•The ZIF-67 (Co-MOF) was on the surface of BiVO4 photoelectrode by electrostatic attraction.•The Co3O4/BiVO4 photoelectrodes were obtained by an additional annealing treatment.•The Co3O4/BiVO4 photoelectrodes exhibited the 3 times PEC performance than the pure BiVO4.•This method can be used to the other semiconductor photoanodes.
Abstract By electronically wiring-up living cells with abiotic conductive surfaces, bioelectrochemical systems (BES) harvest energy and synthesize electric-/solar-chemicals with unmatched ...thermodynamic efficiency. However, the establishment of an efficient electronic interface between living cells and abiotic surfaces is hindered due to the requirement of extremely close contact and high interfacial area, which is quite challenging for cell and material engineering. Herein, we propose a new concept of a single cell electron collector, which is in-situ built with an interconnected intact conductive layer on and cross the individual cell membrane. The single cell electron collector forms intimate contact with the cellular electron transfer machinery and maximizes the interfacial area, achieving record-high interfacial electron transfer efficiency and BES performance. Thus, this single cell electron collector provides a superior tool to wire living cells with abiotic surfaces at the single-cell level and adds new dimensions for abiotic/biotic interface engineering.
The photocatalytic water splitting for generation of clean hydrogen energy has received increasingly attention in the field of photocatalysis. In this study, the Ta2O5/g-C3N4 heterojunctions were ...successfully fabricated via a simple one-step heating strategy. The photocatalytic activity of as-prepared photocatalysts were evaluated by water splitting for hydrogen evolution under visible-light irradiation (λ > 420 nm). Compared to the pristine g-C3N4, the obtained heterojunctions exhibited remarkably improved hydrogen production performance. It was found that the 7.5%TO/CN heterojunction presented the best photocatalytic hydrogen evolution efficiency, which was about 4.2 times higher than that of pure g-C3N4. Moreover, the 7.5%TO/CN sample also displayed excellent photochemical stability even after 20 h photocatalytic test. By further experimental study, the enhanced photocatalytic activity is mainly attributed to the significantly improve the interfacial charge separation in the heterojunction between g-C3N4 and Ta2O5. This work provides a facile approach to design g-C3N4-based photocatalyst and develops an efficient visible-light-driven heterojunction for application in solar energy conversion.
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•Ta2O5 modified g-C3N4 heterojunction were prepared by a one-step heating strategy.•The heterojunction can greatly enhance visible-light hydrogen evolution activity.•The 7.5%TO/CN exhibited best photoactivity and high photochemical stability.•The heterojunction can use as a promising candidate in solar energy conversion.
Core-shell structured ZnCo2O4@ZnWO4 nanowire arrays have been successfully synthesized for advanced asymmetric supercapacitors.
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One of the most effective tactics to promote the ...electrochemical performance of supercapacitors is to design and synthesize hybrid binder-free electrodes with core-shell structures. In this work, hierarchical ZnCo2O4@ZnWO4 core-shell nanowire arrays grown on nickel foam are successfully fabricated via a facile two-step hydrothermal route and subsequent thermal treatment. The ZnCo2O4 nanowire arrays supported on nickel foam serve as the backbone for anchoring ZnWO4 nanosheets. When tested as binder-free electrodes for supercapacitors, the as-prepared ZnCo2O4@ZnWO4 hybrid electrode exhibits an ultrahigh specific areal capacitance of 13.4 F cm−2 at a current density of 4 mA cm−2 and superb cycling stability (98.5% retention after 5000 continuous cycles at a current density of 100 mA cm−2). Furthermore, an asymmetric supercapacitor based on ZnCo2O4@ZnWO4//active carbon is successfully designed. The as-designed asymmetric supercapacitor can achieve a maximum energy density of 24 Wh kg−1 at a power density of 400 W kg−1. Moreover, two as-prepared asymmetric supercapacitor devices in a series connection are able to light up a white light-emitting diode over 30 min. The outstanding electrochemical properties of the hybrid electrode demonstrate that it holds great potential for next generation energy storage applications.
Free-standing two-dimensional MnO2/carbon sphere/graphene (MCG) films are rationally designed and used as efficient electrode materials for supercapacitor. Carbon sphere/graphene (CG) films are ...firstly constructed through a simple vacuum filtration method, then MCG electrodes are prepared by simply floating CGs on KMnO4 solution at room temperature. CG films act as the reducing agents as well as freestanding substrates. Birnessite-type MnO2 in situ grow on the surface of carbon spheres and graphene nanosheets. In the unique structure, carbon spheres spaced sandwich-like porous structures can provide plenty of paths for electrolyte-ion penetration. After decorating with high performance MnO2, MCG films can deliver a gravimetric capacitance of 319.3 F g−1 and a volumetric capacitance of 277.8 F cm−3, much higher than graphene and CG films. More importantly, the electrodes also exhibits high gravimetric and volumetric energy densities of 29.4 Wh kg−1 and 25.6 Wh L−1, respectively, as well as excellent cycling stability with 94.1% of its initial capacitance after 5000 charge-discharge cycles at a current density of 5 A g−1.
Constructing the high-performance photoanode is critical to improve photoelectrochemical (PEC) efficiency, but it is still an inevitable challenge to rationally fabricate the organic-inorganic ...hybrid-photoanode system. For the first time, we report a novel hybrid-photoanode built from ultrathin NiFe-MOF and TiO2 by a sacrifice template method. The in-situ etch of NiFe-layered double hydroxide (LDH) on the surface of TiO2 has been successfully realized in the coordination environment, for creating coordinately unsaturated metal sites on NiFe-MOF. The coordinately unsaturated metal sites could significantly promote the water oxidation kinetic, compared with conventional electrode/electrolyte interface. The photocurrent density of the NiFe-MOF/TiO2 has reached about 3.35 times of bare TiO2 at 1.23 V (vs. RHE), and the incident photon to current conversion efficiency (IPCE) value has been improved up to 42% (at 390 nm). The significant augment of the charge injection (ηinjection) of 92.8% and charge separation (ηseparation) efficiency of 37.4% has also been exhibited. Moreover, NiFe-MOF/TiO2 shows a long-term stability ( < 10% decay) after 4 h of continuous illumination. This work provided a novel and rational strategy about the integration of the inorganic semiconductor and organic MOF, which can provide a new insight into understanding MOF-based catalysts for PEC water splitting.
NiFe-MOF nanosheets were in-situ loaded on the surface of TiO2 to boost photoelectrochemical water splitting for the first time. The NiFe-MOF/TiO2 as a desirable hybrid-photoanode will benefit for in-depth understanding the behavior of organic-inorganic system on the solar energy conversion. Display omitted
•NiFe-MOF plays an important role in the PEC performance of TiO2 photoanode.•Ni and Fe sites synergistically facilitate the water oxidation kinetics.•Ultra-thin structure of NiFe-MOF helps to improve the charge transfer rate.•The favorable stability endows NiFe-MOF/TiO2 with great potential in the future.
Graphitic carbon nitride (g-C3N4) with layered structure represents one of the most promising metal-free photocatalysts. As yet, the direct one-step synthesis of ultrathin g-C3N4 nanosheets remains a ...challenge. Here, few-layered holey g-C3N4 nanosheets (CNS) were fabricated by simply introducing a piece of nickel foam over the precursors during the heating process. The as-prepared CNS with unique structural advantages exhibited superior photocatalytic water splitting activity (1871.09 μmol h–1 g–1) than bulk g-C3N4 (BCN) under visible light (λ > 420 nm) (≈31 fold). Its outstanding photocatalytic performance originated from the high specific surface area (240.34 m2 g–1) and mesoporous structure, which endows CNS with more active sites, efficient exciton dissociation, and prolonged charge carrier lifetime. Moreover, the obvious upshift of the conduction band leads to a larger thermodynamic driving force for photocatalytic proton reduction. This methodology not only had the advantages for the direct and green synthesis of g-C3N4 nanosheets but also paved a new avenue to modify molecular structure and textural of g-C3N4 for advanced applications.
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