Low Potential Difference Research Articles

Breaking the Mutual-Constraint of Bifunctional Oxygen Electrocatalysis via Direct O─O Coupling on High-Valence Ir Single-Atom on MnOx.

Insufficient bifunctional activity of electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is the major obstruction to the application of rechargeable metal-air batteries. The primary reason is the mutual constraint of ORR and OER mechanism, involving the same oxygen-containing intermediates and demonstrating the scaling limitations of the adsorption energies. Herein, it is reported a high-valence Ir single atom anchored on manganese oxide (IrSA-MnOx) bifunctional catalyst showing independent pathways for ORR and OER, i.e., associated 4e- pathway on high-valence Ir site for ORR and a novel chemical-activated concerted mechanism for OER, where a distinct spontaneous chemical activation process triggers direct O─O coupling. The IrSA-MnOx therefore delivers outstanding bifunctional activities with remarkably low potential difference (0.635V) between OER potential at 10mA cm-2 and ORR half-wave potential in alkaline solution. This work breaks the scaling limitations and provides a new avenue to design efficient and multifunctional electrocatalysts.

Cobalt Phosphide Decorating Metallic Cobalt With a Nitrogen‐Doped Carbon Nano‐Shell Surpasses Platinum Group Metals for Oxygen Electrocatalysis Applications

ABSTRACTIt has been a long‐standing challenge to cultivate capable and resilient oxygen electrocatalysts with higher activity, low price, and long lifetime to replace the commonly used platinum group metals, i.e., Pt for oxygen reduction reaction (ORR) and RuO2/IrO2 for oxygen evolution reaction (OER). This work presents a promising approach to address the challenges associated with oxygen electrocatalysis by introducing a cobalt phosphide/metallic cobalt (Co2P/Co) core wrapped in a nitrogen‐doped conductive carbon (CN) nano‐shell, demonstrated as Co2P/Co@NC. The strong chemical bonding between metallic cobalt and phosphorus, nitrogen and conductive carbon contributes to the enhanced conductivity and stability of the electrocatalyst. The nitrogen doping in the carbon shell provides additional Co–N active sites, which are crucial for ORR activity. Co2P/Co@NC demonstrates promising activity and stability compared to noble metals such as Pt for ORR in an alkaline medium. This suggests its potential as a cost‐effective alternative to Pt‐based catalysts. Further, due to factors such as strong cobalt‐phosphide bonding, high cobalt oxidation states and excellent conductivity of the nitrogen‐doped carbon shell, the Co2P/Co@NC outperforms noble metal oxides like iridium dioxide (IrO2) and ruthenium dioxide (RuO2) for OER. Co2P/Co@NC exhibits a low potential difference of 0.63 V, which is among the lowest reported for bifunctional electrocatalysts capable of both ORR and OER. Overall, the described strategy offers a promising avenue for developing efficient, low‐cost and stable electrocatalysts for oxygen reactions, which are crucial for various electrochemical energy conversion and storage technologies, such as fuel cells and metal–air batteries.

Co/CoOx–N–C bifunctional nanocatalyst derived from carbothermally optimized graphene networks with in-situ formed zeolitic imidazolate framework for high performance zinc-air batteries

Rechargeable zinc-air batteries are underpinned by high-performance and durable bifunctional oxygen electrocatalysts. Among the platinum-group metals (PGMs)-free catalysts, the redox-active cobalt-nitrogen-carbon (Co/CoOx–N–C) based materials are promising, however require further structural improvements. This work utilises extremely porous graphene networks (EGO) of hierarchical porosity to in-situ grow ZIF-67 nanocrystals extensively and homogeneously within the porous structure. A simple carbonization of nanoZIF-67@EGO not only generates finely dispersed redox capable Co/CoOx–N–C active sites with the help of residual oxygen functional groups of EGO, but also produces 2-3 dimensional hierarchical porous and conducting structure, readily facilitating high electrochemical surface area. This characteristic structure synergistically contributes to rapid charge and mass transfer rates along with high activity and stability for both ORR and OER. Here, it is worth mentioning that to produce equivalent catalyst material involving different graphitic or template supports requires prolonged and multi-step synthesis routes. The optimized catalyst delivers low potential difference of 0.86 V for bifucntional activity by offering superb ORR half-wave potential of 0.83 V vs RHE and limiting current density of 5.85 mA cm−2 in 0.1 M KOH electrolyte. Zinc-air battery exhibits peak power density of ∼175 mW cm−2 and specific capacity of ∼767 mAh g−1, along with durable cycling round trip efficiency of >63 % (correspond to low voltage gap of ∼0.74 V). These characteristics are better than numerous M–N–C based catalysts reported in the literature. This new strategy holds a great potential to boost the development of diverse MOFs and carbon-based electrocatalysts for a wide range of energy storage and conversion technologies.

A synergistic modification strategy for enhancing the cycling stability and rate capacity of single-crystal nickel-rich cathode materials

Ni-rich layered LiNi0.8Co0.1Mn0.1O2 (NCM811) is considered to be one of the most promising cathode materials due to its advantages of high specific capacity, lower cost and environmental friendliness. However, the relatively high nickel content in the LiNi0.8Co0.1Mn0.1O2 layered cathode materials leads to the instability of the internal structure and surface of the materials during long-term cycling, which results in the deterioration of electrochemical performance. In this study, single-crystal NCM811 (SNCM811) was prepared using a convenient solid-state method. By doping Al into SNCM811 (SNCMAl) and purposefully low-temperature surface treatment with a small amount of LiPF6, a Ni-rich single-crystal NCM811 modified by both Al bulk doping and LiF surface coating (SNCMAl@LiF) was obtained. The reversible capacity of SNCMAl@LiF with a cutoff voltage of 2.7–4.3 V at 0.1C is 200.3 mAh·g−1. And the capacity retention of the single-crystal cathode materials is 92.4 % with capacity of 171.07 mAh·g−1 after 100 cycles at 1C. Even at high rate of 10C, the discharge specific capacity maintains 148.8 mAh·g−1, demonstrating excellent electrochemical performance. The dual-modified single-crystal material has the lowest potential difference and electrochemical impedance without intragranular cracks and crystal slips after 100 cycles. Stronger AlO bond in single crystals reduced the degree of cation mixing and maintained the stability of the layered structure. LiF-modified surface can promote the transfer of Li+, maintain the stability of the electrode/electrolyte interface and then improve the electrochemical performance of cathode materials. Al-doping and LiF-coating provides a guidance on how to enhance the electrochemical performance of Ni-rich single-crystal cathode materials.

Electrochemical synthesis of graphite nanorings under UV irradiation

This paper describes a new way to synthesize graphite nanoparticles based on UV-irradiation energy. Graphite rods are electrochemically exfoliated at 80 °C in the presence of low potential difference (70 V) under UV irradiation. The obtained nanostructures are in the form of nanofibers and nanorings. They are studied using Scanning Electron Microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL). PL spectra typically shows strong luminescence in the visible region (350–700 nm) and the most important emission is observed at 320 nm.

Delineating leachate-groundwater interaction at Gyadi-Gyadi dumpsite, Kano, using natural electromagnetic (EM) field detector and Vertical Electrical Sounding (VES)

Geophysical investigations are mostly used for hydrogeological studies, mining, geotechnical investigation and environmental surveys. Geophysical investigation of groundwater within the dumpsite is highly critical because the extent of interaction between leachate plume/contaminated zone and aquifer zones could significantly reduce groundwater quality. The textural complexity and clay content of soils could change their electrical properties, thus reflecting inconsistent resistivity values using the resistivity method. This research investigates the extent of leachate infiltration from waste dumpsite into groundwater at Gyadi-Gyadi Kano State, using natural Electromagnetic (EM) field and Vertical Electrical Sounding (VES) methods. Six natural EM profiles were obtained in various locations within the study area using PQWT-TC 150 model. Six VES data points were occupied along the EM profile lines using SAS 1000 ABEM resistivity meter. The two techniques employed revealed some intercalations of low resistivity (conductive) as well as very low electrical potential differences in the study area. The low resistivity media are mixtures of leachates into groundwater units, thereby creating formations from the surface to a depth of about 40 m. The first and second layers have experience leachate-aquifer interaction in the northern, southern and eastern parts of the study area to about 40 m depth, and the leachate-aquifer interaction has extended to the deep aquifer of about 70 m depth at the western part. Shallow aquifer has not been infiltrated by leachate at about >100 m away from the waste dumpsite. Therefore, for potable groundwater exploitation in this area, it is advised that boreholes should be sited >100 m away from the dumpsite, where leachate-aquifer interaction has attenuated. The natural EM field detector is evidently constrained by issues of over-generalization and summation of potential values, probably due to its relatively low resolution. Hence it might not be capable of precisely delineating varying geological units. In contrast, the resistivity method is able to delineate and discretize the subsurface into sub-units of different resistive zones. This implies that VES is better suited for accurately defining the true subsurface geology, while the NEF detector is effective for determining the extent of a leachate plume.

Rapid heating synthesis of ultrafine PtCo nanoparticles anchored on carbon nanofibers as high-performance bifunctional oxygen electrocatalysts for zinc-air batteries

Herein, rapid heating strategy was introduced to synthesize ultrafine PtCo nanoparticles attached to carbon nanofibers (CNFs) by a high heating rate (HHR) up to about 50 °C s−1. This novel tactic is beneficial to the formation and the homogeneous distribution of ultrathin PtCo nanoparticles on CNFs. The acquired PtCo/CNFs-HHR exhibits a half-wave potential of 0.88 V for ORR, along with a low potential difference ΔE of 0.79 V. When used as the cathode catalyst of ZABs, PtCo/CNFs-HHR displays a high open circuit voltage of 1.454 V, large peak power density of 138.6 mW cm−2, and excellent charge–discharge cycle stability over 300 cycles.

Effectively Inhibiting Charge Injection and Dielectric Loss of High Permittivity Inorganic Materials by Rationally Coating Organic Polymer for Achieving High Output Charge Density

AbstractAlthough high permittivity of inorganic materials (possibly two orders larger than organic polymers) is theoretically considered as ideal triboelectric materials, their high leakage property and low contact potential difference with metal electrodes lead to failure to obtain high triboelectric charge density. Besides, the internal space charge accumulation as a result of their defect levels reduces the output charge density and causes dielectric loss or even dielectric breakdown under charge injection in charge‐excitation triboelectric nanogenerator (CE‐TENG). Herein, this study proposes high permittivity and low dielectric loss inorganic materials as triboelectric layers. In order to prevent charge injection passing through the surface of inorganic materials caused by air breakdown under charge excitation, an organic polymer is coated, which has high permittivity, big polarizability, none charge traps, and large work function difference with metal electrodes. After optimizing the high dielectric inorganic layer and the coated organic polymer layer, the output charge of CE‐TENG based on 1 mm PZT‐5H coated with P(VDF‐TrFE‐CFE) achieves 2.83 mC m−2, 6.5 times of CE‐TENG based on 1 mm PZT‐5H, breaking the historical record for inorganic material TENG. This work clarifies the material selection criteria for CE‐TENG and provides a deeper understanding of charge transfer mechanism of inorganic materials.

Carbon Fiber Film with Multi-Hollow Channels to Expedite Oxygen Electrocatalytic Reaction Kinetics for Flexible Zn-Air Battery.

The high oxygen electrocatalytic overpotential of flexible cathodes due to sluggish reaction kinetics result in low energy conversion efficiency of wearable zinc-air batteries (ZABs). Herein, lignin, as a 3D flexible carbon-rich macromolecule, is employed for partial replacement of polyacrylonitrile and constructing flexible freestanding air electrodes (FFAEs) with large amount of mesopores and multi-hollow channels via electrospinning combined with annealing strategy. The presence of lignin with disordered structure decreases the graphitization of carbon fibers, increases the structural defects, and optimizes the pore structure, facilitating the enhancement of electron-transfer kinetics. This unique structure effectively improves the accessibility of graphitic-N/pyridinic-N with oxygen reduction reaction (ORR) activity and pyridinic-N with oxygen evolution reaction (OER) activity for FFAEs, accelerating the mass transfer process of oxygen-active species. The resulting N-doped hollow carbon fiber films (NHCFs) exhibit superior bifunctional ORR/OER performance with a low potential difference of only 0.60V. The rechargeable ZABs with NHCFs as metal-free cathodes possess a long-term cycling stability. Furthermore, the NHCFs can be used as FFAEs for flexible ZABs which have a high specific capacity and good cycling stability under different bending states. This work paves the way to design and produce highly active metal-free bifunctional FFAEs for electrochemical energy devices.

Mung Seeds Under Constant Low Potential Difference During Post-Germination When Sprout Length Grows

Low potential difference 𝟎.𝟎𝑽𝒐𝒍𝒕 𝟏.𝟓𝑽𝒐𝒍𝒕, 𝟑.𝟎𝑽𝒐𝒍𝒕, 𝟒.𝟓𝑽𝒐𝒍𝒕, and 𝟔.𝟎𝑽𝒐𝒍𝒕 are applied during the growth of sprout length after germination and post-germination of mung seeds in open-air conditions. The sprout length decreases with an increase in potential difference and graphs show non-linear variations. Thus, this potential difference produces a negative impact on the sprout length elongation of seeds. The decrease in the sprout length may be due to lesser diffusion through the cell wall or due to the weakening of the activity of the other cell components leading to a slower rate of cell division. This may have an impact on the process of preservation of seeds.

Anisotropic Lens-Shaped Mesoporous Carbon with Bifunctional Dual Metal Single Atom Electrocatalyst for Na Seawater Battery

Seawater is a promising electrolyte that can replace conventional distilled water-based electrolytes in that they are affordable and abundant. In the Na seawater battery, oxygen evolution reaction and oxygen reduction reaction occur in a single electrode during the charge and discharge process respectively. To obtain high energy efficiency of the Na-seawater battery, both oxygen electrocatalytic activity should be improved. In addition, the electrochemical reaction occurring in natural seawater may be hindered by chlorine ions. Side reactions such as chlorine evolution reaction or poisoning of electrocatalyst may occur during the charge/discharge process. In this study, dual metal single atom (DSA) loaded anisotropic lens-shaped mesoporous carbon is prepared for an electrode material in a Na-seawater battery. The DSA loaded anisotropic lens-shaped mesoporous carbon is synthesized by polymer interfacial self-assembly of block copolymer (BCP, Poly(ethylene oxide)-b-polystyrene, PEO-b-PS) and immiscible homopolymer (Poly(methyl methacrylate), PMMA). During the self-assembly, pre-dissolved inorganic precursors assemble with BCPs constructing the ordered mesoporous structure. Followed by proper carbonization and chemical etching, DSA loaded anisotropic lens-shaped mesoporous carbon is prepared. Using the natural seawater, the half-cell performance on the rotating disk electrode (RDE) of DSA (Fe-Nx/Co-Nx) loaded mesoporous carbon shows the lower potential difference (EOER-EORR) than a single atom (Fe-Nx) loaded mesoporous carbon, commercial Pt/C (20 wt%) and commercial Ir/IrO catalyst. Based on the RDE result, electrocatalyst performance in seawater half-cell (Na || Seawater) exhibits a concordant result. In addition to the electrochemical results, the performance of the DSA electrocatalyst is confirmed by comparing the activities of chlorine and oxygen species on DSA model through density functional theory calculation.

A Novel Read Scheme Using GIDL Current to Suppress Read Disturbance in 3-D nand Flash Memories

In this paper, a novel read scheme using gate-induced drain leakage (GIDL) current is proposed to suppress read disturbance in 3-D NAND flash memories. The proposed read scheme is demonstrated through the technology computer-aided design (TCAD) simulation. In the selected string, GIDL current is not generated due to the low potential difference. On the other hand, in the unselected string, holes are accumulated under the selected cell and potential of the selected cell is enhanced due to the GIDL current before the read operation. The potential differences between the selected and adjacent cells are decreased and maximum electric field (Em) is decreased. Therefore, soft programming in the selected cell during the read operation is decreased and hot carrier injection (HCI) between selected and adjacent cells is reduced completely. The proposed read scheme can be applied to high stacked WL layers over 200 layers.

Identification of Geothermal Potential in Block Ciasmara Sector II, Mount Salak Area, Based on the Correlation of the Active Directory Magnetotelluric (ADMT) and Self-Potential Methods

Indonesia possesses significant geothermal potential, with the largest share located in West Java, accounting for up to 21.7% distributed across 44 locations in 11 regencies. One such location with geothermal potential is in Block Ciasmara Sector II, the Mount Salak area, Bogor Regency, characterized by manifestations such as hot spring bathing pools. This research aims to understand the distribution of geothermal reservoirs in the study area, where these reservoirs contain hot fluids that can be harnessed for renewable energy generation. The methodology used in this research involves a correlation between the Active Directory Magnetotelluric (ADMT) and Self-Potential (SP) methods. A total of 3 ADMT measurements were conducted along tracks ranges from 5-8 meters, while the SP method involved 7 measurement points with coordinates distributed around the geothermal manifestations in the Mount Salak area. The data obtained were then visualized in 2D and 3D to gain insights into the distribution and orientation of the reservoir layers in the study area. The results indicate a correlation between the ADMT and Self-Potential methods. In Line 01 of the ADMT, located in the western part, there is a correlation with high potential difference values on the SP map ranges from 47.6-82.1 mV, suggesting the presence of tuff layers rich in alteration minerals. This is confirmed by the 2D ADMT modeling, which shows that the clay cap is thicker compared to Line 02 and Line 03, associated with the presence of alteration minerals in the clay cap. This correlation also applies to Line 03, which has low potential difference values ranges from 4.9-25.3 mV, indicating a response from lapilli rocks. This is corroborated by the 2D model, which reveals thickening of the lapilli rock layer on Line 03.Keywords: ADMT, Geothermal, Mount Salak, Reservoir, Self-Potential.

Application of frequency selection and geoelectrical sounding methods for mapping of leachate’s pathways in an active dumpsite

Contamination of surrounding environments is one of the threats to the proper maintenance of municipal waste sites in developing nations. This study integrates natural electromagnetic (EM) field and geoelectrical sounding methods to assess the leachate’s pathways in the near-surface layers and groundwater system in and around an active dumpsite. Five natural EM traverses were obtained in varying orientations using PQWT-TC 150 model. Fifteen vertical electrical sounding (VES) data points were randomly occupied using SAS 4000 ABEM resistivity meter. The two techniques revealed some intercalations of conductive and resistive media in the study area. The conductive media are composed of mixtures of leachates into clay and groundwater units, thereby creating zones of very low electrical potential differences from the surface to a depth beyond 30 m. A zone of leachate-aquifer’s interphase exists between the third layer and the fourth layer. The directions of the fluid flow are in the S–N and SE–NW trends, which could be linked to the fault towards the northwestern part of the study area. The fluid dynamics, however, justified the reason for the thick conductive materials being mapped at the northwestern and northern parts of the study area.

Improved heat and corrosion resistance of high electrical conductivity Al-Mg-Si alloys by multi-alloying of Ce, Sc and Y

In order to improve the corrosion and heat resistance of Al-Mg-Si alloy conductor materials, Ce, Sc, Y and Zr were added in Al-Mg-Si alloy to regulate the microstructure. The Al-Mg-Si-Ce-Sc-Y alloy was designed with excellent pitting and intergranular corrosion resistance by obtaining the micron-sized Fe-containing second phase with a lower potential difference to Al matrix, more dispersed grain boundary precipitates with a higher proportion of Si particles, narrower width of PFZ and ideal distribution of intergranular precipitates. The Al-Mg-Si-Ce-Sc-Y alloy also maintained higher hardness, strength and electrical conductivity after overaging and annealing and the corrosion/heat resistance mechanisms were proposed.

Ni-Doped La0.6Sr0.4CoO3 Perovskite as an Efficient Electrocatalyst for Oxygen Reduction and Evolution Reactions in Alkaline Media

The Co-based perovskite La0.6Sr0.4CoO3 has received significant attention as a potential electrocatalyst for its oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) due to its abundance, facile synthesis, and high oxygen kinetics. However, research on the catalytic performance of Ni-doped La0.6Sr0.4Co1−xNixO3 as a bifunctional cathode catalyst for Zn-air batteries (ZABs) is still scarce. In this work, lanthanum strontium cobalt-based perovskite catalysts with various Ni contents (La0.6Sr0.4Co1−xNixO3, x = 0, 0.2, 0.5, and 0.8) were synthesized using a simple combustion method. The effects of Ni doping on the morphology, structure, surface oxygen-related species, and valence states of the transition metals of the perovskite were characterized. The electrochemical behaviors of the perovskite catalysts in both ORR and OER were also assessed. The characterization results revealed that proper Ni doping can decrease particle size, increase surface oxygen vacancies, and create mixed valence states of the transition metal and, thus, lead to improvement of the electrocatalytic activity of perovskite catalysts. Among the different perovskite compositions, La0.6Sr0.4Co0.8Ni0.2O3 exhibited the best ORR/OER activity, with a higher limiting current density, smaller Tafel slope, higher half-wave potential, lower overpotential, and lower potential difference than the other compositions. When La0.6Sr0.4Co0.8Ni0.2O3 was applied as the cathodic catalyst in a primary ZAB, it delivered a peak power density of 81 mW cm−2. Additionally, in rechargeable ZABs, the La0.6Sr0.4Co0.8Ni0.2O3 catalyst exhibited a lower voltage gap (0.94 V) and higher stability during charge–discharge cycling than the commonly used catalyst Pt/C. These results indicate that Ni-doped La0.6Sr0.4Co0.8Ni0.2O3 is a promising bifunctional electrocatalyst for ZAB.

Adding Fe/dicyandiamide to Co-MOF to greatly improve its ORR/OER bifunctional electrocatalytic activity

Exploring efficient non-precious metal oxygen electrocatalysts for oxygen reduction/evolution reactions (ORR/OER) is of great importance in electrochemical energy conversion devices like metal-air battery. Among them, carbon-based composites derived from metal-organic framework (MOF) exhibit excellent catalytic performance in ORR/OER. In this paper, Co-MOF-67 was firstly prepared, and then mixed with FeCl3·6 H2O and dicyandiamide, followed by a one-step pyrolysis to obtain bamboo-like nitrogen-doped carbon nanotubes. For the samples, Fe and Co nanoparticles were encapsulated in the front end of the carbon nanotubes and the presence of new (n)-diamond carbon was unexpectedly found. The obtained catalyst (FeCo@CNTs-60) has an onset potential of 1.04 V for ORR in alkaline solution, which is close to the commercial Pt/C (40 wt% Pt) of 1.05 V. The onset potential of 1.02 V in quasi-neutral solution exceeds that of Pt/C of 0.99 V. In addition, FeCo@CNTs-60 exhibited a low potential difference of 0.81 V between OER and ORR potentials. The alkaline zinc-air batteries, fabricated with the sample as the electrocatalyst of air electrode, exhibit higher peak power density and stability than Pt/C, while the rechargeable batteries present superior cycling discharge/charge stability at 5 mA·cm−2 and 10 mA·cm−2. In particular, the battery with FeCo@CNTs-60 was conducted for continuous over 1300 h of ultra long-term cycle charging / discharging test at a current density of 5 mA·cm−2, and it reveals excellent stability with high voltage efficiency and also presents superior cycle charging / discharging stability after replacing the Zn plates and electrolyte.

Bio‐Inspired Polyanionic Electrolytes for Highly Stable Zinc‐Ion Batteries

AbstractFor zinc‐ion batteries (ZIBs), the non‐uniform Zn plating/stripping results in a high polarization and low Coulombic efficiency (CE), hindering the large‐scale application of ZIBs. Here, inspired by biomass seaweed plants, an anionic polyelectrolyte alginate acid (SA) was used to initiate the in situ formation of the high‐performance solid electrolyte interphase (SEI) layer on the Zn anode. Attribute to the anionic groups of −COO−, the affinity of Zn2+ ions to alginate acid induces a well‐aligned accelerating channel for uniform plating. This SEI regulates the desolvation structure of Zn2+ and facilitates the formation of compact Zn (002) crystal planes. Even under high depth of discharge conditions (DOD), the SA‐coated Zn anode still maintains a stable Zn stripping/plating behavior with a low potential difference (0.114 V). According to the classical nucleation theory, the nucleation energy for SA‐coated Zn is 97 % less than that of bare Zn, resulting in a faster nucleation rate. The Zn||Cu cell assembled with the SA‐coated electrode exhibits an outstanding average CE of 99.8 % over 1,400 cycles. The design is successfully demonstrated in pouch cells, where the SA‐coated Zn exhibits capacity retention of 96.9 % compared to 59.1 % for bare Zn anode, even under the high cathode mass loading (>10 mg/cm2).

Bio-Inspired Polyanionic Electrolytes for Highly Stable Zinc-Ion Batteries.

For zinc-ion batteries (ZIBs), the non-uniform Zn plating/stripping results in a high polarization and low Coulombic efficiency (CE), hindering the large-scale application of ZIBs. Here, inspired by biomass seaweed plants, an anionic polyelectrolyte alginate acid (SA) was used to initiate the in situ formation of the high-performance solid electrolyte interphase (SEI) layer on the Zn anode. Attribute to the anionic groups of -COO- , the affinity of Zn2+ ions to alginate acid induces a well-aligned accelerating channel for uniform plating. This SEI regulates the desolvation structure of Zn2+ and facilitates the formation of compact Zn (002) crystal planes. Even under high depth of discharge conditions (DOD), the SA-coated Zn anode still maintains a stable Zn stripping/plating behavior with a low potential difference (0.114 V). According to the classical nucleation theory, the nucleation energy for SA-coated Zn is 97 % less than that of bare Zn, resulting in a faster nucleation rate. The Zn||Cu cell assembled with the SA-coated electrode exhibits an outstanding average CE of 99.8 % over 1,400 cycles. The design is successfully demonstrated in pouch cells, where the SA-coated Zn exhibits capacity retention of 96.9 % compared to 59.1 % for bare Zn anode, even under the high cathode mass loading (>10 mg/cm2 ).

Insight into the selective oxidation behavior of organic pollutants via Ni-N4-C mediated electron transfer pathway

Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) is a hopeful method for organic pollutants degradation. However, conventional AOPs often suffer from various disturbances in applications, such as organic matter, inorganic ions, pH, etc. Herein, a novel Ni(Ⅱ)-doped g-C3N4 (Ni4.60CN) catalyst with Ni-N4-C structure was prepared, which exhibited outstanding PMS activation ability. The Ni-N4-C active sites facilitated the electron transfer from pollutants to PMS and achieving high selectivity toward pollutant degradation. Then, integrating experimental and theoretical results, the origin of this selectivity was revealed, indicating that organic pollutants with low vertical ionization potential (VIP), high the highest occupied molecular orbital energy (EHOMO), and low potential differences between organics and Ni4.60CN (marked as EPD) are more beneficial to be degraded. This study unravels the electron transfer mechanism induced by Ni-N4-C sites in Ni4.60CN /PMS activation system and provides a comprehensive insight into the selective oxidation behavior of various pollutants.