Driven by the persisting poor understanding of the sluggish kinetics of the hydrogen evolution reaction (HER) on Pt in alkaline media, a direct correlation of the interfacial water structure and ...activity is still yet to be established. Herein, using Pt and Pt–Ni nanoparticles we first demonstrate a strong dependence of the proton donor structure on the HER activity and pH. The structure of the first layer changes from the proton acceptors to the donors with increasing pH. In the base, the reactivity of the interfacial water varied its structure, and the activation energies of water dissociation increased in the sequence: the dangling O−H bonds < the trihedrally coordinated water < the tetrahedrally coordinated water. Moreover, optimizing the adsorption of H and OH intermediates can re‐orientate the interfacial water molecules with their H atoms pointing towards the electrode surface, thereby enhancing the kinetics of HER. Our results clarified the dynamic role of the water structure at the electrode–electrolyte interface during HER and the design of highly efficient HER catalysts.
On nickel–platinum alloy nanoparticles under alkaline conditions, the reactivity of interfacial water varies with its structure and the order of water dissociation. The inclusion of nickel re‐orientates interfacial water molecules with their hydrogen atoms pointing towards the electrode surface, thereby enhancing the kinetics of the hydrogen evolution reaction (HER).
Heterostructures exhibit considerable potential in the field of energy conversion due to their excellent interfacial charge states in tuning the electronic properties of different components to ...promote catalytic activity. However, the rational preparation of heterostructures with highly active heterosurfaces remains a challenge because of the difficulty in component tuning, morphology control, and active site determination. Herein, a novel heterostructure based on a combination of RuMo nanoalloys and hexagonal N‐doped carbon nanosheets is designed and synthesized. In this protocol, metal‐containing anions and layered double hydroxides are employed to control the components and morphology of heterostructures, respectively. Accordingly, the as‐made RuMo‐nanoalloys‐embedded hexagonal porous carbon nanosheets are promising for the hydrogen evolution reaction (HER), resulting in an extremely small overpotential (18 mV), an ultralow Tafel slope (25 mV dec−1), and a high turnover frequency (3.57 H2 s−1) in alkaline media, outperforming current Ru‐based electrocatalysts. First‐principle calculations based on typical 2D N‐doped carbon/RuMo nanoalloys heterostructures demonstrate that introducing N and Mo atoms into C and Ru lattices, respectively, triggers electron accumulation/depletion regions at the heterosurface and consequently reduces the energy barrier for the HER. This work presents a convenient method for rational fabrication of carbon–metal heterostructures for highly efficient electrocatalysis.
A novel heterostructure based on uniform RuMo nanoalloys and hexagonal N‐doped carbon nanosheets is prepared through a combination of hard template and anion‐exchange methods. The obtained material exhibits excellent electrocatalytic activity for the hydrogen evolution reaction. Theoretical calculation confirms that the heterosurfaces play a crucial role in accelerating the hydrogen evolution activity.
We report a new enantiomeric pair of superatomic silver clusters, R/S-Ag 17 , prepared from chiral alkynyl ligands. R-Ag 17 and S-Ag 17 possess C 3 symmetry and emit near-infrared (NIR) light with a ...quantum yield (QY) of 8.0% under ambient condition as well as NIR circularly polarized luminescence (CPL) as a result of the chirality of the excited states. Both experiments and theoretical calculations indicate for the first time that the CPL originates from transitions between superatomic 1P z (along the C 3 axis) and 1S orbitals. This work opens a new avenue for CPL-active metal nanoclusters by utilizing chiral alkynyl ligands and enlightens the chirality transfer from chiral protecting ligands to superatomic states in metal clusters.
Alloying is an efficient chemistry to tailor the properties of metal clusters. As a class of promising radiosensitizers, most previously reported metal clusters exhibit unitary function and cannot ...overcome radioresistance of hypoxic tumors. Here, atomically precise alloy clusters Pt2M4 (M = Au, Ag, Cu) are synthesized with bright luminescence and adequate biocompatibility, and their composition‐dependent enzyme mimicking activity and radiosensitizing effect is explored. Specifically, only the Pt2Au4 cluster displays catalase‐like activity, while the others do not have clusterzyme properties, and its radiosensitizing effect is the highest among all the alloy clusters tested. By taking advantage of the sustainable production of O2 via the decomposition of endogenous H2O2, the Pt2Au4 cluster modulates tumor hypoxia as well as increases the efficacy of radiotherapy. This work thus advances the cluster alloying strategy to produce multifunctional therapeutic agents for improving hypoxic tumor therapy.
Atomically precise alloy clusters Pt2M4 (M = Au, Ag, Cu) are synthesized with bright luminescence and adequate biocompatibility. The experimental results reveal that the Pt2Au4 cluster displays catalase‐like activity and its radiosensitizing effect is the highest. By taking advantage of the sustainable production of O2 via decomposition of endogenous H2O2, the Pt2Au4 cluster modulates tumor hypoxia as well as increases the efficacy of radiotherapy.
Solar-driven interfacial evaporation is increasingly used in desalination due to its excellent evaporation performance. The continuous evaporation of water would lead to an increase in the salinity ...of the evaporator, which has been often neglected and rarely exploited. In this work, a calcium alginate hydrogel and nickel foam composited membrane (CHN) was proposed as a new platform for constructing solar-powered hybrid systems with the function of synchronous desalination and salinity power generation. The calcium alginate hydrogels can reduce the enthalpy of water evaporation and convert the salinity gradient between the evaporator and seawater into electrical energy. The evaporation rate of the mixed system (CHN-CB) with carbon black (CB) as the solar absorber is greater than 2.1 kg m
−2
h
−1
. Additionally, under 1 sun, the system achieved a maximum short-circuit current of 20.3 mA m
−2
and generated an extra electrical power of 5.3 mW m
−2
. As a universal multi-energy conversion platform, the CHN membranes can combine different photothermal materials for synchronous evaporation and salinity gradient power generation. These results open new paths for the combination of desalination and power generation, demonstrating the potential for diversified use of blue energy.
A calcium alginate hydrogel and nickel foam composite membrane (CHN) can achieve desalination and salinity gradient power generation by solar energy. The CHN membrane can be used as a universal solar conversion platform to obtain blue energy.
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•A high-efficiency and sustainable adsorbent was developed for RB5 removal.•Lotus pollen-derived hierarchical porous carbons (LPHPCs) show exceptional adsorption capacity.•The maximal ...equilibrium adsorption capacity reaches 615.6 mg/g on LPHPCs.•The adsorption isotherms, kinetics and thermodynamics were systematically studied.
The removal of azo dye from wastewater is urgent due to its massive discharge from various industries and high toxicity. Adsorption is an efficient removal method, but it is limited by the low adsorption capacity of the present adsorbents. Herein, a high-efficiency and sustainable adsorbent for Reactive Black 5 (RB5) was developed, which was obtained using lotus pollen as carbon precursors followed by carbonization and activation with KOH. The as-prepared lotus pollen-derived hierarchically porous carbons (LPHPCs) showed exceptional adsorption performance for RB5, the maximal equilibrium adsorption capacity can reach 615.6 mg/g on LPHPC-2.5, and 269.6 mg/g on LPHPC-1.0, which were far superior to that of commercial activated carbon (CAC) (94.7 mg/g). Their adsorption performance for RB5 under different conditions was examined, such as different initial concentration, adsorbent dosage, inorganic salt concentration, temperature and pH. The adsorption isotherms, kinetics, thermodynamic properties and mechanisms were systematically investigated in depth. The results demonstrated that the adsorption process of RB5 onto LPHPCs involved dominant physical adsorption together with necessary chemical adsorption. The comparative advantages of LPHPCs over CAC for RB5 adsorption were ascribed to the higher specific surface area and larger appropriate pore volume, higher degree of graphitization and better affinity. The findings revealed that LPHPCs are promising adsorbents for the adsorption removal of anionic dyes from wastewater.
Porous nitrogen and oxygen co-doped carbon microtubes (PCMTs) were prepared via carbonization followed by activation of plane tree fruit fluffs (PTFFs) and employed as high-performance supercapacitor ...electrode materials. The pore structures, surface chemistry and degree of graphitization of the final products can be facilely tailored by adjusting the activation temperature, which changed remarkably as the activation temperature increased from 650 to 900 °C. The PCMT-850 obtained by activating at 850 °C possessed despite the second largest specific surface area (1533 m
2
/g), but the highest mesopore ratio (9.13%), the maximal nitrogen content (2.20 at.%) and highest degree of graphitization as well as excellent electrical conductivity. The PCMT-850-based carbon electrode exhibited the highest charge storage capacity with a specific capacitance of 257.6 F/g at a current of 1 A/g and the lowest internal resistance in 6 M KOH. The high supercapacitor performance can be attributed to the combined effects of its pore structure, heteroatom doping effects and degree of crystallinity. The favorable capacitive performance render the waste biomass PTFFs serve as novel resources of nitrogen and oxygen co-doped carbon materials for high-performance supercapacitors.
The traditional air cathode in microbial fuel cell (MFC) usually consists of catalyst layer (CL), supporting layer (SL) and conductive gas diffusion layer (GDL), the overall MFC performance is ...inevitably affected by the additional and expensive adhesives and conductive agents. Here, we developed an integrated air cathode in MFC without any additional SL, GDL or adhesives. The integrated air cathode was self-supporting nitrogen-doped reduced graphene oxide@carbon nanofiber (N-rGO@CNF) hybrid membranes fabricated by electrospinning with subsequent heat-treatment under ammonia atmosphere. The as-fabricated N-rGO@CNFs possessed far superior MFC performance and oxygen reduction reaction (ORR) activity to the pristine nitrogen-doped carbon nanofibers (NCNF) and commercial activated carbon (CAC). The amount of rGO embedded into CNF had prominent influence on their ORR activities and MFC performances. N-5-rGO@CNF had the lowest resistance and the maximal exchange current density, exhibiting desirable oxygen reduction performance via a four-electron pathway. The maximum power density of N-5-rGO@CNF can reach 826 mW m−2 in MFC, which is approximately 9, 2.53 and 1.82 times of pristine NCNF, CAC and Pt/C with values of 91, 327 and 454 mW m−2. The outstanding performance of the integrated air-cathodes originates from the integrality, brevity and hybrid composition of the electrospun nanofiber membrane. The appropriate embedded rGO not only improves the bulk conductivity of the rGO@CNF to promote ion adsorption, but also provides vacancies to accommodate ions, the doped nitrogen atoms facilitate O2 adsorption and/or subsequent O–O bond breaking, thus improving the electrochemical performance of N-rGO@CNF in MFC.
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•An integrated N-rGO@CNF air cathodes with high-efficiency were developed via electrospinning.•The integrated air cathodes showed excellent catalytic performance in Microbial Fuel Cells.•The optimal air cathode (N-5-rGO@CNF) had maximum power density of 20650 mW m−3.•N-5-rGO@CNF exhibited ideal oxygen reduction reaction via a four-electron pathway.
Flax-derived flexible porous nitrogen-doped carbon fibers (PNCFs) with controllable textural structure and nitrogen content are obtained via NH3 activation. The PNCFs-based flexible supercapacitor ...shows high energy and power density.
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•A facile approach to flexible high-performance carbon fiber sheets was disclosed.•The procedure parameters of NH3 activation/doping of flax fabrics were investigated.•The flexible capacitor of PNCF displays an energy density of 174.7 μWh cm−2.
A facile and cost-effective approach to flexible high nitrogen-containing porous carbon fiber sheets (PNCFs) was disclosed. The PNCFs were fabricated through a facile strategy of activation/doping of flax fabrics in ammonia (NH3). The procedure parameters of NH3 modification, such as the timing of NH3 switching, activation temperature and duration time were systematically investigated. PNCFs with the highest specific surface area (SSA) of 1152 m2 g−1, largest pore volume of 0.502 cm3 g−1 and maximal nitrogen content of 5.56 at.% were obtained by activation via NH3 at 900 °C for 45 min after pre-carbonization. The optimized sample PNCF-IV-900-45 with the highest SSA, developed hierarchical micro-mesoporous structure and maximal nitrogen content exhibits a large energy density of 16.4 Wh kg−1 at 100 W kg−1. The NH3-activated flax-derived carbon fiber sheets assembled into a flexible supercapacitor also shows preeminent electrochemical performance and the flexibility. The symmetric flexible capacitor by PNCF-IV-900-45 electrodes displays a remarkable specific energy density of 174.7 μWh cm−2 at 500 μW cm−2, which results from the hierarchical porous structure and N functionalities. The synergistic combination of the hierarchical micro-mesoporous textures, high specific surface area, N-doping and flexibility of flax-based PNCFs to the enhanced electrochemical performance in flexible supercapacitor.
Developing high-efficiency electrode materials is always desired for supercapacitor, in order to improve the energy density. Herein, we found that hierarchically porous carbon microtubes (HPCMTs) ...derived from plane tree fruit fluff via self-activation method demonstrated prominent supercapacitor performance as electrode materials, since they possessed hierarchical pore structure consisting of abundant micro- and mesopores, high specific surface area (SSA) and good wettability with electrolyte. The HPCMT-1100-6 with the largest SSA (2805 m2/g) and maximal total pore volume (1.98 cm3/g) was obtained at 1100 °C with dwelling time of 6 h. The HPCMT-1100-6-based cell in organic electrolyte showed an ultrahigh energy density of 46.3 Wh/kg at high power density of 1106 W/kg in 1.0 M TEABF4/AN, as well as splendid rate capability and impressive long-term cyclic stability. The energy density still can retain 35 Wh/kg even at an ultrahigh power density of 83.8 kW/kg, the capacitance retention maintains 96.4% after 10000 cycles at a current density of 10 A/g. This study provided a novel practical sustainable strategy for converting the abundant and low-cost biomass waste into high-valued porous carbons by the green self-activation method for high-energy-density supercapacitor.
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•Hierarchically porous carbon microtubes (HPCMT) were fabricated by a green self-activation method.•The as-fabricated HPCMT possessed ultrahigh specific surface area of 2805 m2/g.•The HPCMT-based cell showed splendid rate capability and prominent long-term cyclic stability.•An ultrahigh energy density of 46.3 Wh/kg can be acquired at high power density of 1106 W/kg.
