Adaptive Fabrication of Electrochemical Chips with a Paste-Dispensing 3D Printer.

Electrochemical (EC) detection is a powerful tool supporting simple, low-cost, and rapid analysis. Although screen printing is commonly used to mass fabricate disposable EC chips, its mask is relatively expensive. In this research, we demonstrated a method for fabricating three-electrode EC chips using 3D printing of relatively high-viscosity paste. The electrodes consisted of two layers, with carbon paste printed over silver/silver chloride paste, and the printed EC chips were baked at 70 °C for 1 h. Engineering challenges such as bulging of the tubing, clogging of the nozzle, dripping, and local accumulation of paste were solved by material selection for the tube and nozzle, and process optimization in 3D printing. The EC chips demonstrated good reversibility in redox reactions through cyclic voltammetry tests, and reliably detected heavy metal ions Pb(II) and Cd(II) in solutions using differential pulse anodic stripping voltammetry measurements. The results indicate that by optimizing the 3D printing of paste, EC chips can be obtained by maskless and flexible 3D printing techniques in lieu of screen printing.

A precisely Assembled Wall-Like Architecture for High Lithium/Sodium Storage.

MXene nanosheets and ordered porous carbons both have their own advantages and disadvantages. Assembling and combining the advantages of the two will be a good choice for battery electrode hosts of active materials. In this work, an electrostatic separation-adsorption strategy is proposed to realize the ordered alternating self-assembly of MXene nanosheets and ordered porous carbon (MPOC), obtaining a unique wall-like porous material with a high conductivity and interconnected porous nanostructure, which strengthens the transfer rate of electrons and ions simultaneously. Meanwhile, the introduction of N-doping from porous carbon into MPOC prolongs the cycle life. When use red phosphorus (RP) as active materials, the MPOC@RP anode exhibited high-capacity output (2454.3 and 2408.1 mAh g-1 in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) at 0.1 C) and long cycle life (the decay rates per cycle of 0.028% and 0.036% after 1500 and 1200 cycles at 2 C in LIBs and SIBs respectively). The successful application in RP anodes displays great potential in other electrode materials such as silicon, sulfur, selenium, and so on. Meanwhile, this strategy is also effective to design other composites materials like MXene and carbon nanotubes, MXene and Graphene, and so on.

Tailoring Ordered Porous Carbon Embedded with Cu Clusters for High-Energy and Long-Lasting Phosphorus Anode.

The natural insulating property and notorious pulverization of volume variation-induced materials during cycling pares the electrochemical activity of red phosphorous (RP) for lithium/sodium-ion batteries (LIBs/SIBs). To work out these issues, a tailored trimodal porous carbon support comprising highly ordered macropores and micro-mesoporous walls embedded with copper (Cu) nanoclusters (Cu-OMC) is proposed to confine RP. The construction of highly conductive copper-carbon wall facilitates fast electrons and ions transportation, while the interconnected and ordered porous structure not only creates enough space to resist the expansion effect of RP but also minimizes the ion diffusion length and enhances ion accessibility (the ion migration coefficient is ten times that of disordered porous carbon). Consequently, the resulting Cu-OMC@RP anode delivers a high reversible capacity (2498.7 mAh g-1 at 0.3 C for LIBs; 2454.2 mAh g-1 at 0.1 C for SIBs), superb rate properties (824.7 mAh g-1 at 10 C for LIBs; 774.2 mAh g-1 at 5 C for SIBs), and outstanding cycling stability (an ultralow decay rate of 0.057% per cycle after 1000 cycles at 10 C for LIBs and 0.048% per cycle at 5 C over 500 cycles for SIBs).

3D Ordered Porous Nanostructure Confers Fast Charge Transfer Rate and Reduces the Electrode Polarization in Thick Electrode.

Lithium batteries with high electrode thickness always possess a poor battery property due to electrode polarization along the thickness direction. Herein, a concept that the electrode polarization can be reduced through the fabrication of 3D ordered interconnected nanostructure in the electrode is put forward. A nitrogen-doped carbon photonic crystal (NCPC) with the ordered interconnected nanostructure is used in the electrode to prove the concept. NCPC can provide a fast charge transfer rate along the thickness direction and a uniform distribution for electrons and lithium ions, resulting in diminishing the concentration polarization and concentration gradient. When NCPC works for lithium-sulfur battery, the thick electrode achieves a fast charge transfer rate and a small voltage gap as well as the thin electrode. The 200 µm thick sulfur cathode obtains a specific capacity (87%) as high as 100 µm thick sulfur cathode. In contrast, the capacity ratio of the electrode made by the traditional coating method is only 45%.

Efficient Bifunctional Catalytic Electrodes with Uniformly Distributed NiN2 Active Sites and Channels for Long-Lasting Rechargeable Zinc-Air Batteries.

Freestanding bifunctional electrodes with outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) properties are of great significance for zinc-air batteries, attributed to the avoided use of organic binder and strong adhesion with substrates. Herein, a strategy is developed to fabricate freestanding bifunctional electrodes from the predeposited nickel nanoparticles (Ni-NCNT) on carbon fiber paper. The steric effect of monodispersed SiO2 nanospheres limits the configuration of carbon atoms forming 3D interconnected nanotubes with uniformly distributed NiN2 active sites. The bifunctional electrodes (Ni-NCNT) demonstrate ideal ORR and OER properties. The zinc-air batteries assembled with Ni-NCNT directly exhibit extremely outstanding long term stability (2250 cycles with 10 mA cm-2 charge/discharge current density) along with high power density of 120 mV cm-2 and specific capacity of 834.1 mA h g-1 . This work provides a new view to optimize the distribution of active sites and the electrode structure.

Graphene/graphitic carbon nitride decorated with AgBr to boost photoelectrochemical performance with enhanced catalytic ability.

A novel graphene nanoplatelets (GNP) bridge between two semiconductors (AgBr and graphitic carbon nitride) was created to boost photoelectrochemical performance. The heterojunction created makes the whole system a Z-scheme catalyst. For the construction of this catalyst, the syringe pump methodology was adopted and different analytical techniques were used for the confirmation of structure and morphology. High angle annular dark field (HAADF), dark field (DF), DF-4 and DF-2 techniques, using Z-contrast phenomena, confirmed the heterostructure (ABGCN) and its composition. The constructed structure showed an enhanced photoelectrochemical and catalytic property against 'acute toxicity category-III (MM)' and 'category-IV (tetracycline hydrochloride (TH))' organic pollutants. The constructed catalyst degraded the MM in 57 min and the TH in 35 min with degradation rates of 0.01489 min-1 and 0.02387 min-1, respectively, due to the accumulation of photogenerated electrons on the conduction band (CB) of g-C3N4 and photogenerated holes on the valence band (VB) of AgBr by the transformation of charges through the graphene bridge. An ion trapping study also revealed that ·O2 and h+ were the active species which actively participated in the photocatalytic reaction.

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO3 - /CO2 System.

Photoelectrochemical carbon dioxide conversion to fuels such as carbon monoxide, methanol, and ethylene exhibits great potential to solve energy issues. Unfortunately, CO2 conversion efficiency is still low due to violent charge recombination at the photoanode. Herein, a novel 3D macroporous ferroelectric heterojunction composed of BiFeO3 and LiNbO3 is developed by a template-assisted sol-gel method, aiming at facilitating charge transfer kinetics. As expected, a tremendous enhancement of photocurrent density (300 times vs bare planar BiFeO3 film) and charge transfer efficiency (up to 76%) is obtained in the HCO3 - /CO2 system without any cocatalyst. The photoelectrochemical performance is switchable by poling to form a depolarization electric field. Photoelectrochemical impedance spectroscopy reveals that the charge transfer resistance decreases due to the synergistic effect of BiFeO3 3D macroporous skeleton and LiNbO3 passivation layer by tuning surface states. These results suggest a novel strategy for enhancing photoelectrochemical water oxidation as the anodic reaction of CO2 reduction.

A Host-Configured Lithium-Sulfur Cell Built on 3D Nickel Photonic Crystal with Superior Electrochemical Performances.

The insulator of the sulfur cathode and the easy dendrites growth of the lithium anode are the main barriers for lithium-sulfur cells in commercial application. Here, a 3D NPC@S/3D NPC@Li full cell is reported based on 3D hierarchical and continuously porous nickel photonic crystal (NPC) to solve the problems of sulfur cathode and lithium anode at the same time. In this case, the 3D NPC@S cathode can not only offer a fast transfer of electron and lithium ion, but also effectively prevent the dissolution of polysulfides and the tremendous volume change during cycling, and the 3D NPC@Li anode can efficiently inhibit the growth of lithium dendrites and volume expansion, too. As a result, the cell exhibits a high reversible capacity of 1383 mAh g-1 at 0.5 C (the current density of 837 mA g-1 ), superior rate ability (the reversible capacity of 735 mAh g-1 at the extremely high current density of 16 750 mA g-1 ) with excellent coulombic efficiency of about 100% and an excellent cycle life over 500 cycles with only about 0.026% capacity loss per cycle.

Development of an accelerated leaching method for incineration bottom ash correlated to toxicity characteristic leaching protocol.

Heavy metals and some metalloids are the most significant inorganic contaminants specified in toxicity characteristic leaching procedure (TCLP) in determining the safety of landfills or further utilization. As a consequence, a great deal of efforts had been made on the development of miniaturized analytical devices, such as Microchip Electrophoresis (ME) and µTAS for on-site testing of heavy metals and metalloids to prevent spreading of those pollutants or decrease the reutilization period of waste materials such as incineration bottom ash. However, the bottleneck lied in the long and tedious conventional TCLP that requires 18 h of leaching. Without accelerating the TCLP process, the on-site testing of the waste material leachates was impossible. In this study, therefore, a new accelerated leaching method (ALM) combining ultrasonic assisted leaching with tumbling was developed to reduce the total leaching time from 18 h to 30 min. After leaching, the concentrations of heavy metals and metalloids were determined with ICP-MS or ICP-optical emission spectroscopy. No statistical significance between ALM and TCLP was observed for most heavy metals (i.e., cobalt, manganese, mercury, molybdenum, nickel, silver, strontium, and tin) and metalloids (i.e., arsenic and selenium). For the heavy metals with statistical significance, correlation factors derived between ALM and TCLP were 0.56, 0.20, 0.037, and 0.019 for barium, cadmium, chromium, and lead, respectively. Combined with appropriate analytical techniques (e.g., ME), the ALM can be applied to rapidly prepare the incineration bottom ash samples as well as other environmental samples for on-site determination of heavy metals and metalloids.

Introduced Hierarchically Ordered Porous Architecture on a Separator as an Efficient Polysulfide Trap toward High-Mass-Loading Li-S Batteries.

The severe shuttle effect and the depletion of active sulfur result in performance deterioration, presenting two formidable issues that must be overcome to achieve high-mass-loading lithium-sulfur batteries. Herein, we reported a composite separator by introducing carbon photonic crystals with a hierarchically ordered porous structure on a commercial separator. The ordered structure and interconnected hierarchical macro-meso-micropore network of the composite separator facilitate efficient trapping of polysulfides and rapid transport of lithium ions. The high ion diffusivity promotes the conversion of polysulfides enhancing sulfur utilization and mitigating the occurrence of "dead sulfur" on the surface of the separator. Impressively, under a high sulfur loading of 3 mg cm-2, the lithium-sulfur battery with the composite separator displayed a high reversible capacity of 1582 mA h g-1 at 0.1 C and an excellent long-term cycling performance with a decay rate of as low as 0.033% per cycle over 1500 cycles at 1 C. Surprisingly, the battery represented a high reversible capacity of 935 mA h g-1 at 0.2 C even at a sulfur loading of 6.71 mg cm-2. The design of the composite separator underscores the pivotal role of carbon architecture in improving battery performance and brings a bright prospect to enable the commercialization of high-mass-loading lithium-sulfur batteries.

Hoya-like Hierarchical Porous Architecture as Multifunctional Phosphorus Anode for Superior Lithium-Sodium Storage.

Designing nanostructured hosts with the merits of high conductivity, strong trapping ability, and long-term durability to improve the insulating nature and extreme volume change of red phosphorus (RP) is a promising option for the development of high-performance lithium/sodium-ion batteries (LIBs/SIBs). Here, a multifunctional RP immobilizer is proposed and fabricated, which comprises a nitrogen-doped hollow MXene sphere (NM) planted with the dual-sided porous carbon network (DCNM). In such a configuration, the highly conductive macroporous NM not only facilitates fast electron transport but also acts as the capturing center to entrap polyphosphide through strong chemical adsorption, while the uniformly distributed micromesoporous carbon network in or out of the sphere provides reliable RP accommodation and alleviates the volume expansion, as well as creates interpenetrating ion diffusion and electron transport channels. Benefiting from the synergistic effect of the triple-shelled architecture and the exclusive restraint, the Hoya-like DCNM@RP anode exhibits significantly enhanced electrochemical performances for LIBs and SIBs, delivering a combination of high reversible capacity, splendid rate properties, and extended cycling performance: up to 1800 cycles with 0.01% per cycle capacity decay for LIBs and 0.024% per cycle over 1000 cycles for SIBs at 2 C.

Dendrite-Free and Ultra-Long-Life Lithium Metal Anode Enabled via a Three-Dimensional Ordered Porous Nanostructure.

Constructing a stable non-dendritic lithium metal anode is the key to the development of high-energy batteries in the future. Herein, we fabricated nitrogen-doped carbon photonic crystals in situ in the macropores of carbon papers as a porous skeleton and confined hosts for metallic lithium. The large specific surface area of the carbon photonic crystal reduces the current density of the electrode. The three-dimensional ordered microstructure promotes uniform charge distribution and uniform lithium deposition and inhibits the volume expansion of metallic lithium. The as-prepared lithium metal anode exhibits prominent electrochemical performance with a small hysteresis of less than 95 mV beyond 180 cycles at an extremely high current density of 15 mA cm-2. When the as-prepared lithium metal anode is coupled with the sulfur cathode, the obtained full cell displays enhanced capacitive properties and cycle life. Compared with the bare Li anode, the full cell exhibits more than 300 cycles of cell life and a 70 mA h g-1 higher discharge capacity.

Three-Dimensional Ordered Porous Nanostructures for Lithium-Selenium Battery Cathodes That Confer Superior Energy-Storage Performance.

Lithium-selenium (Li-Se) batteries suffer from the problems of polyselenides dissolution and volume expansion of active materials during the charge/discharge process. Moreover, the heavy atomic mass of selenium atoms limits the capacitive property of a Li-Se battery. Porous materials as the host for selenium particles reported by previous research studies are often disordered in pore structure and nonuniform in pore size. Herein, we report that a three-dimensional (3D) nitrogen-doped carbon photonic crystal (NCPC) with an ordered, interconnected structure was synthesized via a simple method to be the host of active materials. In addition, we prepared a Se-rich Se1-xSx by introducing a small amount of sulfur into a selenium ring to reduce the molecular mass but still keep the high electronic conductivity. As cathodes for a Li-Se battery, amorphous Se-rich Se1-xSx@NCPC composites exhibited high electrochemical performance with a specific capacity of 692 mA h g-1 at 0.1 Ag1-, an excellent rate capability of 526 mA h g-1 at 3 Ag1-, and an outstanding cycling property with an ultralow decay rate of 0.0132% per cycle at 0.6 Ag1- over 1000 cycles. Moreover, the pouch cell of Se1-xSx@NCPC composites also showed a good property with an energy of 253 Wh kg-1 at 0.1 Ag1- and an outstanding rate energy of 192 Wh kg-1 at 1.5 Ag1-, manifesting great potential in practical application.

Three-Dimensional-Ordered Porous Nanostructures for Lithium-Sulfur Battery Anodes and Cathodes Confer Superior Energy Storage Performance.

The nonuniformity of microscopic electrochemical reaction of electrodes essentially results in the partial reaction discrepancy and subsequent partial overheating, which is the most critical safety problem of the battery system in electric vehicles. Herein, we report a class of DLPC@S/DLPC@Li full cell based on a distinctly constructed double-layer photonic crystal (DLPC) with a three-dimensional-ordered interconnected structure. This full cell not only ensures the uniformity of microscopic electrochemical reaction but also solves common problems such as low conductivity of sulfur, poor cycle life, and lithium dendrite growth. Impressively, the full cell exhibits superior electrochemical performance pertaining to high reversible capacity of 703.3 mAh g-1 even at an extremely high rate of 10 C and excellent cycle performance with 1200 cycles with about 0.0317% capacity loss per cycle at 0.5 C.