Spinel oxides have attracted widespread interest for electrocatalytic applications owing to their unique crystal structure and properties. The surface structure of spinel oxides significantly ...influences the electrocatalytic performance of spinel oxides. Herein, we report a Li reduction strategy that can quickly tune the surface structure of CoFe
O
(CFO) nanoparticles and optimize its electrocatalytic oxygen evolution reaction (OER) performance. Results show that a large number of defective domains have been successfully introduced at the surface of CFO nanopowders after Li reduction treatment. The defective CFO nanoparticles demonstrate significantly improved electrocatalytic OER activity. The OER potential observed a negative shift from 1.605 to 1.513 V at 10 mA cm
, whereas the Tafel slope is greatly decreased to 42.1 mV dec
after 4 wt % Li reduction treatment. This efficient Li reduction strategy can also be applied to engineer the surface defect structure of other material systems and broaden their applications.
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Nickel oxyhydroxide (NiOOH) is regarded as one of the promising cocatalysts to enhance the catalytic performance of photoanodes but suffers from serious interfacial charge-carrier ...recombination at the photoanode||NiOOH interface. In this work, surface-engineered BiVO4 photoanodes are fabricated by sandwiching an oxygen vacancy (Ovac) interlayer between BiVO4 and NiOOH. The surface Ovac interlayer is introduced on BiVO4 by a chemical reduction treatment using a mild reducing agent, sodium hypophosphite. The induced Ovac can alleviate the interfacial charge-carrier recombination at the BiVO4||NiOOH junction, resulting in efficient charge separation and transfer efficiencies, while an outer NiOOH layer is coated to prevent the Ovac layer from degradation. As a result, the as-prepared NiOOH-P-BiVO4 photoanode exhibits a high photocurrent density of 3.2 mA cm−2 at 1.23 V vs. RHE under the irradiation of 100 mW/cm2 AM 1.5G simulated sunlight, in comparison to those of bare BiVO4, P-BiVO4, and NiOOH-BiVO4 photoanodes (1.1, 2.1 and 2.3 mA cm−2, respectively). In addition to the superior photoactivity, the 5-h amperometric measurements illustrate improved stability of the surface-engineered NiOOH-P-BiVO4 photoanode. Our work showcases the feasibility of combining cocatalysts with Ovac, for improved photoactivity and stability of photoelectrodes.
This paper demonstrates chemi-resistive type and QCM ammonia sensors based on Ti3C2Tx MXene with surface engineering. The morphology and structure composition of Ti3C2Tx MXene were completely tested ...by XRD, SEM, TEM and Raman. The ammonia sensing performance of Ti3C2Tx MXene sensors at room temperature were systematically studied. The QCM sensors show better performance towards ammonia than chemi-resistor sensors. The Ti3C2Tx-S QCM sensor possesses quite sensitivity (49 Hz@100 ppb), high response/recovery capability (33 s/58 s) and good selectivity. XPS was introduced for the surface element status for the potential ammonia adsorption mechanism. It can be mainly related to for lowest average potential for reaction of Ti-S and the additional absorption towards the product nitric oxides enhancing the frequency shift by absorption mass increasing. This work confirms that surface engineering of Ti3C2Tx MXene to be effective method for enhancing gas sensing performance, and the sensor shows potential application for low concentration ammonia sensing.
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•Treated Ti3C2Tx MXene was fabricated via surface engineering with simple solution process.•Chemi-resistance type and QCM gas sensors were fabricated by spin coating method without further treatment.•Ti3C2Tx-S QCM sensors exhibited excellent performance for ammonia gas detection and detection limit was down to 10 ppb.•Potential ammonia absorption and electronic sensing mechanism of surface medicated Ti3C2Tx MXene was discussed.
Single‐cell nanoencapsulation is an emerging field in cell‐surface engineering, emphasizing the protection of living cells against external harmful stresses in vitro and in vivo. Inspired by the ...cryptobiotic state found in nature, cell‐in‐shell structures are formed, which are called artificial spores and which show suppression or retardation in cell growth and division and enhanced cell survival under harsh conditions. The property requirements of the shells suggested for realization of artificial spores, such as durability, permselectivity, degradability, and functionalizability, are demonstrated with various cytocompatible materials and processes. The first‐generation shells in single‐cell nanoencapsulation are passive in the operation mode, and do not biochemically regulate the cellular metabolism or activities. Recent advances indicate that the field has shifted further toward the formation of active shells. Such shells are intimately involved in the regulation and manipulation of biological processes. Not only endowing the cells with new properties that they do not possess in their native forms, active shells also regulate cellular metabolism and/or rewire biological pathways. Recent developments in shell formation for microbial and mammalian cells are discussed and an outlook on the field is given.
Recent developments in single‐cell nanoencapsulation suggest that the field has advanced to the formation of active shells for cell‐in‐shell structures. These active‐shell structures are involved in the dynamic regulation of cellular processes while protecting the cells inside.
Designing high‐performance and cost‐effective electrocatalysts for water splitting at high current density is pivotal for practical industrial applications. Herein, it is found that atomic‐level ...surface engineering of self‐supported nickel phosphide (NiP) nanoarrays via a facile cation‐exchange method can substantially regulate the chemical and physical properties of catalysts by introducing Co atoms. Such surface‐engineered NixCo1–xP endows several aspects of merits: i) rough nanosheet array electrode structure accessible to diffusion of electrolytes and release of gas bubbles, ii) enriched P vacancies companied by Co doping and thus increased active sites, and iii) the synergy of Ni5P4 and NiP2 beneficial to catalytic activity enhancement. By virtue of finely controlling the Co contents, the optimal Ni0.96Co0.04P electrode achieves remarkable bifunctional electrocatalytic performance for overall water splitting at a large current density of 1000 mA cm−2, showing overpotentials of 249.7 mV for hydrogen evolution reaction and 281.7 mV for oxygen evolution reaction. Furthermore, the Ni0.96Co0.04P electrode at 500 mA cm−2 exhibits an ultralow potential (1.71 V) and ultralong durability (500 h) for overall water splitting. This study implies that the atomic‐level surface engineering of the electrode materials offers a viable route for gaining high‐performance catalysts for water splitting at large current density.
The self‐supported NiP nanosheet array electrode with enriched P vacancies and atomic‐level Co doping is achieved by a controlled cation‐exchange strategy excluding complicated chemical reactions and post‐treatment steps. Such NiP nanoarray electrode exhibits excellent performance and long‐term stability (over 500 h) for electrocatalytic water splitting at large current density, outperforming noble‐metal catalysts in electrocatalytic hydrogen evolution reaction and oxygen evolution reaction.
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•Design of a double-layer hydrogel evaporator through 3D printing.•Structures on macro/micro scale were designed to promote high evaporation performance.•Evaporation rate of ...2.78 kg·m−2·h−1 and efficiency of 91.5 % were achieved.•Good solar desalination and wastewater treatment abilities were obtained.
Solar interfacial evaporation has become promising recently because of the growing demand for clean water in human society, and improving the evaporation rate of evaporators is of great importance for efficient seawater desalination. In this work, a novel double-layer Janus hydrogel evaporator with surface structure was fabricated by 3D printing using poly(ethylene glycol) diacrylate (PEGDA) with small amount addition of carbon black (CB), sodium alginate (SA), and sodium lignosulfonate (SL). The printed hydrogel has excellent abilities as a solar evaporator, such as high solar absorption, low thermal conductivity, desired hydrophilicity, and strong mechanical strength. Compared with the traditional 2D evaporators, our evaporator can significantly reduce the evaporation enthalpy of water and localize heat on the interface, these positive effects lead to a high evaporation rate of 2.78 kg·m−2·h−1 of our evaporator with an energy efficiency of 91.5 % under 1 sun, which is significantly higher than the theoretical evaporation rate limit of 2D evaporators (1.46 kg·m−2·h−1) and outperforms the PEGDA-based hydrogel evaporators reported in the literature. Furthermore, this Janus evaporator shows good anti-fouling and wastewater treatment performances. This research promotes the applications of 3D printing hydrogel evaporators through a novel strategy.
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•Surface engineered Ta2O5−x mesocrystals were synthesized.•The sample showed enhanced photocatalytic performance.•Alkali modifications induced increased surface areas and surface ...hydroxyl groups.•Possible degraded pathways and mechanism were proposed.
Mesocrystals are types of fascinating multifunctional materials in fabricating rapid charge transport pathways, and surface engineering could be considered as a significant influencing factor in boosting charge separation for efficient photocatalytic application. In this work, surface engineered Ta2O5−x mesocrystals were synthesized by facile alkali treatment strategy for enhanced visible light photocatalytic tetracycline degradation. The highly enhanced photocatalytic activity could be attributed to the highly increased surface areas and surface hydroxyl groups to compare with those of commercial Ta2O5 and pristine Ta2O5−x mesocrystals, which could provide more surface reactive sites and high electron density center for trapping photo-generated holes. Besides, possible tetracycline transformation pathways over surface engineered Ta2O5−x mesocrystals and visible light photocatalytic mechanism were also proposed in this work. Current work also provides a facile strategy for regulating surface property of ultrawide bandgaps semiconductors for enhanced visible light photocatalytic performance.
Nanoscale surface‐engineering plays an important role in improving the performance of battery electrodes. Nb2O5 is one typical model anode material with promising high‐rate lithium storage. However, ...its modest reaction kinetics and low electrical conductivity obstruct the efficient storage of larger ions of sodium or potassium. In this work, partially surface‐amorphized and defect‐rich black niobium oxide@graphene (black Nb2O5−x@rGO) nanosheets are designed to overcome the above Na/K storage problems. The black Nb2O5−x@rGO nanosheets electrodes deliver a high‐rate Na and K storage capacity (123 and 73 mAh g−1, respectively at 3 A g−1) with long‐term cycling stability. Besides, both Na‐ion and K‐ion full batteries based on black Nb2O5−x@rGO nanosheets anodes and vanadate‐based cathodes (Na0.33V2O5 and K0.5V2O5 for Na‐ion and K‐ion full batteries, respectively) demonstrate promising rate and cycling performance. Notably, the K‐ion full battery delivers higher energy and power densities (172 Wh Kg−1 and 430 W Kg−1), comparable to those reported in state‐of‐the‐art K‐ion full batteries, accompanying with a capacity retention of ≈81.3% over 270 cycles. This result on Na‐/K‐ion batteries may pave the way to next‐generation post‐lithium batteries.
Surface‐amorphized and defect‐rich black niobium oxide@graphene nanosheets are constructed as anode materials for sodium and potassium storage, delivering a high‐rate Na/K storage capacity (123 and 73 mAh g−1, respectively at 3 A g−1) and long‐term cycling stability. Na/K full batteries based on the prepared anodes also demonstrate high energy and power densities.
Three-dimensional (3D) printing by material extrusion is being widely explored to prepare patient-specific scaffolds from biodegradable polyesters such as poly(lactic acid) (PLA). Although they ...provide the desired mechanical support, PLA scaffolds lack bioactivity to promote bone regeneration. The aim of this work was to develop a surface engineering approach for enhancing the osteogenic activity of 3D printed PLA scaffolds. Macro-porous PLA scaffolds were prepared by material extrusion with 70.2% porosity. Polyethyleneimine was chemically conjugated to the alkali-treated PLA scaffolds followed by conjugation of citric acid. These polymer-grafted scaffolds were immersed in the simulated body fluid to yield scaffolds coated with calcium-deficient hydroxyapatite (PLA-HaP). Surface roughness and water wettability were enhanced after surface modification. PLA-HaP scaffolds exhibited a steady release of calcium ions in an aqueous medium for 10 days. The adhesion and proliferation of human mesenchymal stem cells (hMSCs) on PLA-HaP was ~50% higher than on PLA. Mineral deposition resulting from hMSC osteogenesis on PLA-HaP scaffolds was nearly twice that on PLA scaffolds. This was corroborated by the increase in alkaline phosphatase activity and expression of several osteogenic genes. Thus, this work presents a surface modification strategy to enhance the bioactivity of 3D printed scaffolds for bone tissue regeneration.
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•3D printed scaffolds of poly(lactic acid) with 70% porosity were prepared by materials extrusion.•Scaffold surface was modified by grafting polyethyleneimine and citric acid followed by deposition of calcium phosphate.•Scaffolds released calcium ions and exhibited enhanced roughness and water wettability after surface modification.•Adhesion and proliferation of mesenchymal stem cells increased by 50% after surface modification.•Enhanced stem cell osteogenesis on the surface modified scaffolds resulted in doubling of the mineralization.
Surface adsorption behavior and electron transfer determine the catalytic activity in hydrogen evolution reaction (HER). However, the inevitable surface oxidation of NbC hinders electron transfer and ...hydrogen conversion. The surface adsorption behavior and electron transfer of NbC are optimized by doping Cu+ as well as modifying the orbital hybridizations. Benefiting from the introduced electron interaction of Cu+, the lower p-d hybridization between Nb and O reduces the Nb-O bond and affords the Cu-NbC thinner surface oxidation layer. The reduced surface oxidation degree favors electron transfer. Further, the electron orbital hybridization modulates the electron states and optimizes the hydrogen adsorption behavior of Cu-NbC for efficient hydrogen conversion. As the electrochemical results, the obtained Cu-NbC demands 271 mV to drive 10 mA cm−2, which is 50 times higher than that of NbC (only 0.2 mA cm−2 at the same overpotential). Hence, we believe the orbital hybridization manipulation strategy renders a valuable solution for designing efficient HER catalysts.
A orbital hybridization engineering for boosting the HER kinetics by doping Cu+ in NbC is first proposed. The orbital hybridization engineering optimizes the electron structure of Cu-NbC, reducing the surface oxidation layer and optimizing the hydrogen adsorption strength. Then thus, the boosting electron transfer and intermediates conversion promote the HER kinetic. This work paves a new way for rationally designing efficient catalysts for alkaline HER. Display omitted
•Cu+ is doped into NbC by a one-pot molten salt method.•Introduced electron interaction of Cu+ modify p-d hybridization between Nb and O.•The reducing surface oxidation degree favors the electron transfer.•Orbital hybridization engineering optimizes the electron state at Fermi Level.•Efficient electron transfer and optimized adsorption behavior boost the reaction kinetics.
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