Latest ArticlesConstructing anodes with fast ions/electrons transfer paths is an effective strategy to achieve high-performance sodium ion batteries (SIBs)/potassium ion batteries (PIBs). Amorphous carbon is a promising candidate anode for SIBs/PIBs owing to its disordered carbon layers, abundant defects/pores, and low-cost resources. However, the larger radius of Na+/K+ leading to depressed kinetics and poor cycling performance, impeding their further applications. Herein, we propose an efficient strategy to construct of nitrogen, sulfur co-doped hollow carbon nanospheres (NS-HCS) involving an in situ growth of polydopamine on nano-Ni(OH)2 template with subsequent sulfur doping process. During the formation process, the produced Ni nanospheres play as the hard template and catalyst for the formation of hollow carbon nanosphere with partially graphite microcrystalline structure, while the sulfur doping process can enlarge the interlayer space and create more defects on the surface of carbon nanospheres, thus synchronous improve the Na+/K+ insertion and adsorption ability in NS-HCS. With the synergistic control of the enlarged interlayer spacing, high content of pyridinic N/pyrrolic N and graphitization, a hybrid storage mechanism facilitates the transport kinetics and endows the NS-HCS electrode with high capacities and good cycling stability in SIBs and PIB. Benefit from the multiple effects, NS-HCS exhibits the improved capacity of 274.8 mAh/g at 0.1 A/g and excellent cycling stability of 149.5 mAh/g after 5000 cycles at 2.5A/g in SIBs, as well as good potassium ion storage behavior with a high capacity retention of 76.5% after 700 cycles at 1.0 A/g, demonstrating the potential applications of NS-HCS for high-performance SIBs and PIBs
A novel air-stable n-type benzothiaphene endcapped azaarene (BTPQ) and its sulfonated derivative (BSPQ) were prepared via two pathways and characterized by NMR, UV–vis, fluorescence and cyclic voltammetry spectroscopy. Symmetrically introducing four nitrogen atoms into acenes, the semiconductor properties could be changed from p-type to n-type detected through the space charge limited current (SCLC) method. After sulfonation of BTPQ, BSPQ is with deeper frontier orbital energy levels and enhanced the electron mobility.
Photocatalytic recovery, a novel precious metal recycling technology, dedicates to solving the environmental and energy consumption problems caused by traditional technologies. The activation of molecular oxygen (O2) is one of the most critical steps in the whole process. Herein, we regulated the different adsorption intensity of oxygen on the surface by designing phosphate (PO43−) modified titanium oxide (TiO2). The results show that the adsorption of oxygen on the photocatalyst surface is gradually enhanced, which effectively improves the dissolution rate of precious metals. PO43− modification increased the photocatalytic dissolution rate of gold (Au) by 2.8 times. The photocatalytic activity of other precious metals dissolution (such as palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru) and iridium (Ir)) was also significantly improved. It is applied to the recovery of precious metals from spent catalysts and electronic devices to significantly promote the recovery efficiency. This indicates the direction for designing more efficient photocatalysts for precious metal recovery.
One-dimensional carbon nanofibers are widely applied as anode material in the energy storage field due to its unique structure and high conductivity. In this work, one-dimensional ZnSe@N-doped carbon nanofibers (ZnSe@NC NFs) are successfully synthesized by electrospinning and annealed without extra troublesome conditions. ZnSe nanocrystals are enfolded in the N-doped carbon nanofibers, which can act as a protective layer to avoid the volume expansion of active material and promote ion transport during the cycling process. More importantly, the as-synthesized ZnSe@NC NFs are served as the anode material and display the admirable storage properties for Na/K-ion batteries. The one-dimensional ZnSe@NC NFs material shows the high capacity of 237 mAh/g for Na-ion batteries at a current density of 1 A/g for 2000 cycles. Meanwhile, it also delivers a high discharge capacity of 337 mAh/g for K-ion batteries at 0.2 A/g for 300 cycles. Additionally, it is confirmed that the pseudocapacitive contribution of the nano-structure material is up to 54.5% at a scan rate of 0.6 mV/s through the cyclic voltammetry (CV) measurement in K-ion batteries.
The growing food delivery service market has boosted the consumption of packaging materials, and this trend is projected to continue in the following years. The gap between industrial supply and consumer demand from a sustainable viewpoint leads to a need for agricultural cellulosic waste-based materials that bring the idea of trash-to-treasure to fruition. In this paper, we review up-to-date advancements surrounding the food delivery packaging that are derived from agricultural cellulosic waste. Two scenarios in which agricultural feedstock is used as a host or guest material are summarized, and sketch on the individual processing routine is depicted. We further evaluate how the chemical compositions and processing parameters influence the properties of the final products. Current challenges and gaps in developing sustainable packaging materials are identified, with perspectives on these important issues highlighting the importance of process innovation as well as economic and environmental-impact assessment for agricultural cellulosic waste to food delivery packaging.
Lithium-oxygen (Li-O2) batteries are considered as the next generation for energy storages systems due to the higher theoretical energy density than that of Li-ion batteries. However, the high charge overpotential caused by the insulated Li2O2 results in low energy efficiency, side reaction from electrolyte and cathode, and therefore poor battery performance. Designing noble metal-based catalysts can be an effective strategy to develop high-performance Li-O2 batteries with low charge overpotentials and outstanding cycle stability. However, the charge mechanism for noble metal-based catalysts is not clear and even contradictory. Herein, several charge mechanisms of Li2O2 are first discussed. Subsequently, the possible charge processes of Li-O2 batteries with noble metal-based catalysts are illustrated. In addition, the future development for noble metal-based catalysts is outlined.
Platinum exhibits high electrocatalytic activity toward various reactions but might be poisoned by some species. This communication reports a new finding that the electrocatalytic activity of platinum for methanol oxidation will be largely lost in a lead-contaminated environment. This activity loss is demonstrated in an electrochemical cell using a lead counter electrode for measuring the activity of platinum electrode towards methanol oxidation. The recorded methanol oxidation current in this cell is significantly decreased compared with that using a platinum counter electrode. The possible mechanism is related to the adsorption of trace lead ions from the lead counter electrode, as confirmed by comparing the calculated binding energies of platinum and lead ions with oxygen ion. This report is of great importance for reliably designing and efficiently managing direct methanol fuel cells, because trace lead might be present in various components in the fuel cell systems or in air and attention should be paid to its negative effect.
Polyoxometalates (POMs) are important inorganic photochromic materials to be potentially applied in photo-induced switch, energy storage, and even the detection of light. However, due to the limited sensitivity of POMs, it is difficult to realize the photochromic response to weak visible light. In this paper, by the coordination of solvated Pb(II), a new structure-defined chain-like polyoxomolybdate complex of [(Pb(DMF)4)3(P2Mo18O62)2]n (Pb3Mo18, DMF = dimethylformamide) has been demonstrated by a facile solvent-diffusion approach. By virtue of interactions between Pb(DMF)4 and polyoxoanions, Pb3Mo18 shows an ultrasensitive photochromic response to weak visible lights and forms the reduced 'heteropoly blue' species through ligand-to-metal charge transfer (LMCT) process. A new mechanism is firstly proposed here that the 6s orbital lone electron pair on Pb(II) can effectively stabilize the generated hole of oxygen atoms as a result of O→Mo charge transfer. Through the proposed mechanism, the LMCT barrier is drastically lowered and allows the coloration to be occurred even upon weak visible light. Also, because the conductivity of Pb3Mo18 enhances with the increase of reduction extent, its electrochemical impedance signals are proportionally response to irradiation intensity. Especially, for the first time, the polyoxomolybdate composite can be used to detect weak visible light, in which the optical signal can be converted into electrical signal output. Moreover, Pb3Mo18 can be drip-coated on the surface of the screen printed chip electrode, which is facile to the detection of light by portable devices compatible with computers, mobile phones and other electronic equipment. This work not only highlights a new approach to the molecular design of photochromic POMs by the coordination of metal ions with the effect of inert electron pair, but also lays a foundation to extend the application of POMs as light signal sensors.
Hydroxyl radicals (•OH) generated on anode play a vital role in electrochemical oxidation (EO) of organic pollutants for water treatment. Inspired by the four-electron oxygen evolution reaction (OER), we supposed an anode-selection strategy to stabilize deeply oxidized states (*O and *OOH) which are beneficial to generating •OH. To verify the hypothesis, a candidate anode component (MIL-101(Cr), a well-known metal-organic framework with active variable-valence transition metal centers) was used to coat Ti/TiO2 plate to fabricate anodes. Compared to TiO2(101) plane on undecorated anode surface, fast and complete removal of aniline and phenol, and improved energy utilization were achieved on MIL-101(Cr)-coated-Ti/TiO2 anode. Mechanism investigation, including pollutant degradation pathways, showed the predominate contribution (69.60%–75.13%) of •OH in pollutant mineralization. Density functional theory (DFT) computations indicated Cr site in MIL-101(Cr) was more conducive to stabilizing *O and *OOH, leading to thermodynamical spontaneous generation of •OH. This work opens up an exciting avenue to explore •OH production, and supplies a useful guidance to the development of anode materials for EO process.
Spiropyrans (SPs) are a well-known class of photochromic compounds and have found widespread application due to their unique properties. However, for many conventional SPs, high energy ultraviolet (UV) light is commonly essential to drive photoisomerization, leading to poor fatigue resistance. Moreover, the practical application of spiropyrans is hindered by their fast fading speed due to the instability of closed forms (SP) or open forms (MC). Herein, we disclose a novel strategy to address these challenges through introducing both electron-donating substituents to stabilize the SP and dynamic coordination bonds to stabilize the MC. The resulting new spiropyrans complexes exhibit negative photochromic properties, with fast visible light response, good stability of both SP and MC, and significantly improved fatigue resistance.
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