Kinetics Conditioning of (Electro) Chemically Stable Zn Anode with pH Regulation Toward Long-Life Zn-Storage Devices.

The safety, low cost, and high power density of aqueous Zn-based devices (AZDs) appeal to large-scale energy storage. Yet, the presence of hydrogen evolution reaction (HER) and chemical corrosion in the AZDs leads to local OH- concentration increasement and the formation of ZnxSOy(OH)z•nH2O (ZHS) by-products at the Zn/electrolyte interface, causing instability and irreversibility of the Zn-anodes. Here, a strategy is proposed to regulate OH- by introducing a bio-sourced/renewable polypeptide (ɛ-PL) as a pH regulator in electrolyte. The consumption of OH- species is evaluated through in vitro titration and cell in vivo in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy at a macroscopic and molecular level. The introduction of ɛ-PL is found to significantly suppress the formation of ZHS and associated side reactions, and reduce the local coordinated H2O of the Zn2+ solvation shell, widening electrochemical stable window and suppressing OH- generation during HER. As a result, the inclusion of ɛ-PL improves the cycle time of Zn/Zn symmetrical cells from 15 to 225 h and enhances the cycle time of aqueous Zn- I2 cells to 1650 h compared to those with pristine electrolytes. This work highlights the potential of kinetical OH- regulation for by-product and dendrite-free AZDs.

Bio-inspired Ti3C2Tx MXene composite coating for enhancing corrosion resistance of aluminum alloy in acidic environments.

Aluminum alloy (Al alloy) suffers from severe corrosion in acidic solution. Two-dimensional (2D) MXene-based composite coatings show great prospects for corrosion protection on metals used in special conditions. The composite coatings still face challenges in complex functionalization and orientation control. In harsh conditions, the long-term ability and roles of MXene in corrosion protection are still not clear. Here, a bio-inspired myristic-calcium chloride-Ti3C2Tx MXene (MA + CaCl2 + MXene) composite coating is successfully prepared on aluminum alloy (Al alloy) by electrodeposition process. Electrochemical tests, surface morphology, and chemical composition are analyzed to investigate the corrosion resistance and protection mechanism of the MXene coating in acidic solution (0.5 M H2SO4 + 2 ppm HF). As a result, the incorporation of MXene can significantly reduce corrosion current density (7.498 × 10-8 A/cm2) by âˆ¼ 5 orders of magnitude and impedance modulus at 0.01 Hz (|Z|0.01 Hz) value of the composite coating is 196.8 Ω·cm2, which is over 4 times higher than that of bare Al alloy (40.74 Ω·cm2) after immersion test for 72 h. Furthermore, the in-situ corrosion test confirms the enhanced corrosion resistance of the MA + CaCl2 + MXene composite coating. The MXene can increase coating thickness to 23.6 ± 0.4 µm, reduce porosity to (5.845 ± 1) × 10-5, decrease the diffusion coefficients of H+ to (1.587 ± 0.3) × 10-9 cm2/s, and enhance the adhesion of the coating to the substrate (the delamination time exceeds 5 h), thus providing improved anti-corrosion ability. This strategy opens up new prospects for construction of 2D MXene-based anti-corrosion coatings.

Photo-Cross-Linked Polymeric Dispersants of Comb-Shaped Benzophenone-Containing Poly(ether amine).

Efficient dispersion of nanoparticles (NPs) is a crucial challenge in the preparation and application of composites that contain NPs, particularly in coatings, inks, and related materials. Physical adsorption and chemical modification are the two common methods used to disperse NPs. However, the former suffers from desorption, and the latter is more specific and has limited versatility. To address these issues, we developed a novel photo-cross-linked polymeric dispersant, comb-shaped benzophenone-containing poly(ether amine) (bPEA), using a one-pot nucleophilic/cyclic-opening addition reaction. The results demonstrated that the bPEA dispersant forms a dense and stable shell on the surface of pigment NPs through physical adsorption and subsequent chemical photo-cross-linking, which effectively overcome the drawbacks of the desorption occurred in physical adsorption and the specificity of the chemical modification. By means of the dispersing effect of bPEA, the obtained pigment dispersions show high solvent, thermal, and pH stability without flocculation during storage. Moreover, the NPs dispersants show good compatibility with screen printing, coating, and 3D printing, endowing the ornamental products with high uniformity, color fastness, and less color shading. These properties make bPEA dispersants ideal candidates in fabrication dispersions of other NPs.

Dual Confinement of CoSe2 Nanorods with Polyphosphazene-Derived Heteroatom-Doped Carbon and Reduced Graphene Oxide for Potassium-Ion Batteries.

High-capacity and highly stable anode materials are some of the keys to the realization of the application of potassium-ion batteries (PIBs). Cobalt diselenide (CoSe2) has been regarded as a high-potential anode material for PIBs. However, solving the problems of sluggish kinetics and large volumetric expansion during intercalation/deintercalation of K+ ions is always very challenging in terms of cobalt diselenide-based anode materials. Herein, reduced graphene oxide-encapsulated polyphosphazene-derived S, P, and N codoped carbon (SPNC)-coated CoSe2 nanorods (CoSe2⊂SPNC⊂rGO) were designed as PIB anode materials. CoSe2⊂SPNC⊂rGO delivers an excellent reversible capacity of 287.2 mAh g-1 at 100 mA g-1. Benefiting from the coating of heteroatom-doped carbon and encapsulation of rGO, the CoSe2⊂SPNC⊂rGO anodes exhibit a remarkable rate capability (100-1500 mA g-1 current density) and high stability (208.8 mAh g-1 after 500 cycles at 500 mA g-1). The results demonstrate that S, P, and N codoping in carbon layers provides active sites for K+ ion storage and increases the electrical conductivity. More importantly, the dual confinement of CoSe2 nanorods with carbon layers and rGO significantly reduced the volume expansion and kept the electrode structural integrity with repeating intercalation/deintercalation of K+ ions.

Rod-like nickel doped Co3Se4/reduced graphene oxide hybrids as efficient electrocatalysts for oxygen evolution reactions.

In the oxygen evolution reaction (OER), highly active catalysts are essential for reducing the overpotential and improving the slow kinetics of the process. Cobalt selenide (Co3Se4) has always been considered as a promising electrocatalyst for the OER due to the well-suited electronic configuration of the Co ions in it. However, poor exposure of the active sites and low electron conductivity are still its biggest problems. In this study, we report an efficient Ni-doped rod-like Co3Se4 hybridized with reduced graphene oxide (Ni-Co3Se4/rGO) as an OER electrocatalyst. The Ni doping regulates the electronic structure of Co3Se4 and significantly reduces the overpotential of Co3Se4 toward the OER under alkaline conditions. Simultaneously, hybridization of the reduced graphene oxide (rGO) enhances the conductivity which leads to the improvement in OER activity. The Ni-Co3Se4/rGO catalyst shows a lower overpotential (284 mV at 10 mA cm-2) as well as a Tafel slope (71 mV dec-1), which outperformed the benchmark of commercial RuO2. Moreover, Ni-Co3Se4/rGO also shows high stability and long-term durability.

Polyacrylonitrile Infused in a Modified Honeycomb Aluminum Alloy Bipolar Plate and Its Acid Corrosion Resistance.

Bipolar plates, accounting for a large proportion of proton exchange membrane fuel cells (PEMFCs), are highly susceptible to corrosion by H+, SO4 2-, and so on because of the strong acid-rich and oxygen/hydrogen-rich environments. In this work, the corrosion resistance of aluminum alloy bipolar plates modified in the cathodic environment of PEMFCs has been investigated. A honeycomb structure is constructed by anodizing on an aluminum alloy (AA5052) bipolar plate, and a polyacrylonitrile (PAN) film is prepared by infusing PAN solution on the surface. From scanning electron microscopy and atomic force microscopy, we observe that the porous structure of the aluminum alloy surface is more advantageous for enhancing the mechanical engagement between PAN and the aluminum alloy. Therefore, the PAN film is dense and smooth. Electrochemical tests confirm that the PAN film greatly improves the corrosion resistance of the aluminum alloy bipolar plate under the cathodic environment of the PEMFC. When graphene oxide (GO) is added, the charge-transfer resistance (R ct) is not only improved but also the stability under oxygen-rich acidic conditions is prolonged.

Nickel Nitride Particles Supported on 2D Activated Graphene-Black Phosphorus Heterostructure: An Efficient Electrocatalyst for the Oxygen Evolution Reaction.

Hydrogen is regarded as the most promising green clean energy in the 21st century. Developing the highly efficient and low-cost electrocatalysts for oxygen evolution reaction (OER) is of great concern for the hydrogen industry. In the water electrolyzed reaction, the overpotential and the kinetics are the main hurdles for OER. Therefore, an efficient and durable oxygen evolution reaction electrocatalyst is required. In this study, an activated graphene (AG)-black phosphorus (BP) nanosheets hybrid is fabricated for supporting Ni3 N particles (Ni3 N/BP-AG) in the application of OER. The Ni3 N particles are combined with the BP-AG heterostructure via facile mechanical ball milling under argon protection. The synthesized Ni3 N/BP-AG shows excellent catalytic performance toward the OER, demanding the overpotential of 233 mV for a current density of 10 mA cm-2 with a Tafel slope of 42 mV dec-1 . The Ni3 N/BP-AG catalysts also show remarkable stability with a retention rate of the current density of about 86.4% after measuring for 10 000 s in potentiostatic mode.