Latest ArticlesPorous carbon materials doped with atomically dispersed metal sites (ADMSs) are promising electrocatalysts for oxygen reduction reaction (ORR) electrocatalysis. In this work, we fabricated hierarchical porous nitrogen-doped carbon nanofibers with atomically dispersed Fe-N4 sites by carbonization of electrospinning iron-based metal-organic frameworks (MOFs)/polyacrylonitrile nanofibers for ORR electrocatalysis. Remarkably, the resultant carbon nanofibers with atomically dispersed Fe-N4 sites exhibit extraordinary electrochemical performance with an onset potential of 0.994 V and a halfwave potential of 0.876 V in alkaline electrolyte, comparable to the benchmark commercial Pt/C catalyst. The high catalytic performance is originated from the unique hierarchically porous 1D carbon structure and abundant highly active atomically dispersed Fe-N4 sites.
As one of the most environmentally friendly photovoltaic (PV) conversion equipments, aqueousprocessed CdTe nanocrystal solar cells (NC SCs) have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption. However, two issues including interfacial recombination and leakage current seriously restrict their performance. In this paper, insulating polymer poly(vinyl pyrrolidone) (PVP) is introduced into CdTe NC SCs to solve the problems. The experimental results of transmission electron microscopy (TEM), atomic force microscopy (AFM) and dark current measurements, etc., demonstrate the leakage current is effectively suppressed by introducing PVP. Through further designing device structure, the reduction of interfacial recombination after introducing PVP is confirmed. By strategically taking the advantages of PVP properties (e.g., water solubility and thermostability), the power conversion efficiency of the devices with PVP is enhanced by almost 37% compared to pure CdTe devices. This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route. Moreover, it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance.
Solid photocatalysts with high specific surface area, superior photoactivity and ease of recycling are highly desired in chemical process, water treatment and so on. In this study, a facile stepwise sol-gel coating approach was utilized to synthesize Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and convenient magnetic separability (denoted as Fe3O4@SiO2@Pt/mTiO2-x). These photocatalysts consist of magnetic Fe3O4 cores, nonporous insulating SiO2 middle layer and mesoporous anatase TiO2-x shell decorated by Pt nanoparticles (~3.5 nm) through wet impregnation and H2 reduction. As a result of high activity of oxygen-deficiency of black TiO2-x by H2 reduction and efficient inhibition of electron-hole recombination by Pt nanoparticles, the rationally designed core-shell Fe3O4@SiO2@Pt/mTiO2-x photocatalysts exhibit superior photocatalytic performance in rhodamine B (RhB) degradation under visible light irradiation, with more than 98% of RhB degraded within 50 min. These core-shell structured photocatalysts show excellent recyclability under the assistance of magnetic separation with well-retained photocatalytic performance even after running five cycles. This stepwise synthesis method paves the way for the rational design of a high-efficiency recyclable heterogeneous catalyst, including photocatalysts, for various applications.
An ambient pressure-induced calcination process was proposed to prepare g-C3N4 with different structures. The porcelain boat with designed porosity is used to control the ambient pressure to change the diffusion behavior of the reaction molecules, thereby controlling the layer structure and rich pyridinic N content of g-C3N4, thus renders superior lithium storage performance.
Semitransparent organic solar cells (ST-OSCs) have the potentials to open promising applications that differ from those of conventional inorganic ones, such as see-through power windows with both energy generation and heat insulation functions. However, to achieve so, there remain significant challenges, especially for balancing critical parameters, such as power conversion efficiency (PCE), average visible transparency (AVT) and low energy infrared photon radiation rejection (IRR) to realize the full potentials of ST-OSCs. Herein, we demonstrate the new design of ST-OSCs through the rational integration of organic materials, transparent electrode and infrared photon reflector in one device. With the assistance of optical simulation, new ST-OSCs with precise layout exhibit state-of-art performance, with near 30% AVT and PCE of 7.3%, as well as an excellent IRR of over 93% (780-2500 nm), representing one of best multifunctional ST-OSCs with promising perspective for window application.
As a daily food for billions of people for thousands of years, whole grain is rich in phenolic compounds and may have huge potentials to provide natural antioxidants. Herein, owing to the significant biomedical potential, the effect of whole wheat flour solution as antioxidant wound coating for enhanced wound healing has been studied. The results show that the low concentration of whole wheat flour solutions have good biocompatibility and can scavenge radical and intracellular ROS in vitro, accelerating tissue remodeling in vivo to promote wound healing. This kind of whole wheat flour solution has great potential application for cutaneous wound repair.
The synthesized near infrared molybdenum oxide quantum dots perform excellent red fluorescence imaging performance and photothermal performance, which have 600, 650 and 700 nm three unique peaks excited at 540 nm, with a high quantum yield around 20%. Meanwhile, with 808 nm NIR laser excitation, 10 mg/mL modified Molybdenum oxide quantum dots can increase temperature up to 72.2 ℃ within 150 s and 77.7 ℃ within 270 s, respectively.
Commercial carbon clothes have the potential to be utilized as supercapacitor electrodes due to their low cost and high conductivity. However, the negligible surface area of the carbon clothes serves as a serious impediment to their utilization. Herein, we report a facile calcination activation method for carbon cloths to realize remarkable comprehensive electrochemical performance. The activated carbon cloths deliver a high areal capacitance (1700 mF/cm2), good rate capability, and stable cycling performance up to 20, 000 cycles. Owing to the stability in the wide potential window, a designed symmetric capacitor can function in a cell voltage of 2.0 V and delivers high volumetric and gravimetric energy densities of 7.62 mWh/cm3 and 18.2 Wh/kg, respectively. The remarkable electrochemical performance is attributed to rich microporosity with high surface area, superior electrolyte wettability, and stability in wide potential window.
Graphene oxide (GO), an important chemical precursor of graphene, can stably disperse in aqueous surrounding and undergo aggregation as metal cations introduced. The usual instability of GO with ions is caused by the shielding effect of ions and crosslinking between GO and ions. However, the dynamic stability of GO under ions exchange still remains unclear. Here, we investigated the dynamic dispersion stability of GO with metal ions and observed a redispersion behavior in concentrated Fe3+ solution, other than permanent aggregation. The exchange with Fe3+ ions drives the reversion of zeta (ζ) potential and enables the redispersion to individual GO-Fe3+ complex sheets, following a dynamic electric double layer (EDL) mechanism. It is found that the specifically strong electrostatic shielding effect and coordination attraction between Fe3+ and functional oxygen groups allows the selective redispersion of GO in concentrated Fe3+ solution. The revealed dynamic dispersion stability complements our understanding on the dispersive stability of GO and can be utilized to fabricate graphene-metal hybrids for rich applications.
Reusable palladium nanoparticles highly dispersed in porous and hydrophilic interpenetrating polymer networks (IPN), i.e., Pd@IPN hybrid gels, are employed for catalysis of Suzuki and Heck coupling reactions. Good yields are obtained with high turnover frequencies when the reactions are run with very low Pdloadings. The use of IPN gives better recyclability than that of crosslinked polyvinyl alcohol alone. The polymer networks allow the reactants to have easy access to the Pd metals. The catalysts combine high activity with the reusability offered by the heterogeneous system, without the need for strong coordination or chelating ligands.
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