Manganese (Mn) oxides have attracted considerable attention for their affordability, environmental compatibility, and favorable electrochemical properties, making them promising materials for various environmentally relevant electrochemical applications, such as capacitive deionization and ion-selective electrochemical separations. However, conventional Mn oxide synthesis methods typically involve strong oxidants, external heating, extended synthesis times, or expensive equipment, underscoring the need for a greener, more energy-efficient synthesis approach for Mn oxides with reduced environmental footprints. Inspired by the natural Mn oxidation process driven by sunlight-induced reactive radicals, this study presents a greener and photochemically assisted method for synthesizing Mn oxide solids by optimizing aqueous chemistry conditions to accelerate Mn2+ oxidation. During nitrate photolysis in the presence of a pyrophosphate buffer, Mn2+ was rapidly oxidized to form birnessite, eliminating the need for external heating and significantly reducing energy input. The resulting Mn oxides exhibited high pseudocapacitance performance, achieving a capacitance of 172.4 ± 16.6 F/g, surpassing Mn oxides synthesized via redox oxidation (144.1 ± 4.2 F/g) and those commercially purchased (14.5 ± 0.6 F/g). By integrating enhanced pseudocapacitance with sustainable, energy-efficient synthesis, this study introduces a promising strategy for producing Mn oxides with significant potential for environmentally relevant electrochemical applications.

Struvite (NH4MgPO4·6H2O) mineralization is an effective technique for removing ammonium and phosphate species from wastewater. However, its wider use faces obstacles because of the copresence of various pollutants in wastewater and the additional requirement for magnesium to achieve proper supersaturation conditions. To address these challenges, this study developed novel mineral-hydrogel composites that can remove ammonium and phosphate simultaneously via heterogeneous struvite and calcium phosphate (CaP) mineralization in hydrogel matrices. The composites include in situ formed struvite and CaP mineral seeds, decreasing the nucleation energy barrier of struvite and CaP formation and promoting their heterogeneous nucleation kinetics even under undersaturation conditions in bulk solution. The dual struvite and CaP seeded composites can simultaneously reduce the ammonium and total phosphate concentrations up to 60% (26.3 mg of N/g) and 91% (9.54 mg of P/g), respectively. The average particle sizes in composites were increased from 6.12 to 14.8 nm after wastewater treatment. Moreover, various ions commonly existing in wastewater did not significantly interfere with the removal of ammonium and phosphate. Thus, these new mineral-hydrogel composites can provide an innovative way to lower nutrient levels before discharge to streams. Moreover, encapsulating ammonium and phosphate in mineral-hydrogel composites enables their upcycling in agricultural or biorefinery applications.

Pt-doped VO2(B) thin films were prepared on quartz glass substrates using 500 degrees C RF magnetron sputtering. The study explored the impact of varying Pt concentrations on the microstructure, surface morphology, and thermotropic phase transition properties of the VO2 films. X-ray diffraction analysis revealed that Pt doping altered the phase of the VO2 films from VO2(B) to VO2(M) under identical preparation conditions, with the intensity of the VO2(M) phase diffraction peaks decreasing as the doping concentration increased. Field emission scanning electron microscopy analysis demonstrated that the size of the island-like nuclei particles on the surface of the PtVO2 films increased with higher Pt doping levels. The thermotropic resistance of the Pt-VO2 films varied with temperature, with phase transition temperatures (TM) ranging from 47.1 degrees C to 52.3 degrees C, significantly lower than the 67.5 degrees C observed in the single-crystalline VO2 films. In situ infrared spectroscopy tests conducted on the Pt-3 samples indicated a 12.2 % reduction in the absorptivity at the thermal IR atmospheric window around lambda ti 8.9 mu m, showcasing properties of low IR emissivity while modulating the IR radiation. Overall, Pt-doped VO2 films exhibit thermotropic phase transition properties with significant potential for applications in new energy- efficient smart windows.

High‐bandgap Cu2ZnSnS4 (CZTS) thin film solar cells on transparent electrodes show favorable characteristics for new photovoltaic application scenarios including building‐integrated photovoltaics, vehicle‐integrated photovoltaics, and top cell for tandem structure. However, the efficiency of pure sulfide kesterite CZTS thin film solar cells on transparent substrates lags behind that on traditional Mo substrates. Herein, fabrication of high‐quality CZTS absorber films and efficient solar cells on fluorine‐doped tin oxide substrates from dimethyl sulfoxide solution is reported. The formation of harmful secondary phases in CZTS film is suppressed by simply adjusting the chemical stoichiometry in the precursor solution, leading to the development of 5.88% CZTS solar cells. Sodium (Na) doping further promotes grain growth and suppresses secondary phase, contributing to the reduced interface recombination and improved device performance. A champion device with an efficiency of 8.36% has been achieved with 1% Na doping, underscoring the significance of the solution process in achieving highly efficient kesterite solar cells on transparent electrodes.

Emerging portable energy systems with integrated sustainability and improved safety have garnered growing interest in wearable electronics. Herein, a self-charging zinc-ion battery is successfully developed by integrating a PVDF-ZnO piezoelectric separator immersed in a quasi-solid-state hydrogel electrolyte (prepared using a 3 m Zn(CF3SO3)(2)) solution that is sandwiched between a FeVO4 cathode and a zinc anode. This battery effectively captures energy through controlled tapping, eliminating the need for external charging and enabling sustainable energy storage. This self-charging battery can be charged up to 181.23 mV under continuous tapping for 300 s. Upon the cease of tapping, there is a slight decline in the induced potential, which then stabilizes and maintains a consistent potential. Five self-charging batteries connected in series and tapped simultaneously for 300 s generate a potential of 290 mV, whereas five batteries connected in series and tapped one by one induce a potential of 345 mV. This is the first time that a piezoelectric self-charging zinc-ion battery is reported. This study unveils a transformative strategy for realizing next-generation wearable electronics with a self-charging zinc-ion battery design that prioritizes both sustainability and safety.

In this work, a full flexible metal-free battery is developed using a QSS hydrogel electrolyte sandwiched between a PANI anode and PPy cathode enabling the battery to operate and maintain its performance while bent or twisted.

In this work, a novel self-charging zinc-ion battery is developed using an FeVO4·H2O cathode and zinc anode coupled with a concentrated electrolyte composed of 1 m Zn(CF3SO3)2 and 5.16 m LiTFSI enabling the battery to operate and maintain self-charging capability under cold conditions.

The environmentally friendly elements composed of high bandgap pure sulfide Cu2ZnSnS4 (CZTS) semiconductor has broad prospects for building integrated photovoltaic, double-sided, and semi-transparent solar cells when fabricated on transparent substrates. The key issues limiting the performance of CZTS solar cells are poor absorber quality and unfavorable band energy alignment causing serious charge carrier recombination. Here, thefabrication of CZTS solar cells are reported on fluorine-doped tin oxide (FTO) substrates from dimethyl sulfoxide solution and the effects of the Cd and Ag alloying on device performance. Characterizations show that Cd alloying greatly decreases defect concentration and converts Cliff-type band alignment to favorable Spike-type, leading to greatly improved current density. Further, Ag alloying eliminates near-horizontal grain boundaries and passivates defects in both bulk and heterojunction interface, resulting in a champion device with a power conversion efficiency of 10.3%, the highest efficiency pure sulfide CZTS solar cell on FTO substrate. The results demonstrate the great application potential of pure sulfide kesterite solar cells.

Metal-free batteries present a unique opportunity as sustainable energy storage devices. Herein, we present an all-organic metal-free NH4+ ion full battery that can operate at a low temperature of 0 °C.

Metal-free batteries provide a more sustainable and environmental-friendly alternative to current popular batteries using nonrenewable metals. Alcohols as anti-solvents have been used in the electrolytes in Li-ion batteries (LIBs) and zinc-ion batteries (ZIBs), as they bring new properties with regards to the solvation sheath and water activity to the electrolytes. In this work, we explore the application of methanol (CH3OH) as an antisolvent in the electrolyte in a metal-free ammonium-ion battery (AIB) for operation at low temperature, with polyaniline (PANI) as anode and polypyrrole (PPy) as cathode. The addition of CH3OH alters the solvation sheath of the NH4+ and reduces the activity of H2O by forming hydrogen bonds in the solution, thereby decreasing the freezing point of the electrolyte. Through this strategy, a lower freezing point of the electrolyte is realized without using ultrahigh concentration of salts in aqueous solution. The resulted full metal-free battery using a 4 m ammonium acetate electrolyte is able to operate at -20°C, while long cycling at subzero temperatures has never been reported for ammonium-ion batteries before. Further, the CH3OH-H2O volume ratio can be optimized to 65-35, leading to an ammonium-ion battery that exhibits a capacity of 73.23, 48.32 and 32.88 mAh/g, as well as a capacity retention of 87.79%, 90.12% and 74.33% after 100 cycles at 0.1 A/g, at 25°C, 0°C and -20°C, respectively. In this work, an antisolvent is used in non-metal ammonium-ion batteries for the first time, engendering the battery anti-freezing properties. As such, this study opens the door to the realization of novel metal-free batteries with lower cost and better performance for applications in frigid environments.

The use of non-metal ammonium ions (NH4+) as effective charge carriers in battery systems is receiving wide-spread attention because of their light weight and small hydration shells in water as well as abundancy of the elements. The research concerning NH4+ ion redox chemistry in batteries is still in its infancy, mainly because the large ionic radius of NH4+ would require a host material to have a wider open structure and thus limits the choice of electrode materials. NH4+ ion redox chemistry is dominated by non-ionic chemical bonding such as hydrogen bonding with some covalent bonding in nature which plays a significant role in electrochemical performance of the battery. In this work, an in-situ intercalation technique is utilized to synthesize polyaniline-intercalated vanadium oxide with a nanoflower morphology for increased surface area and enhanced NH4+ ion (de)intercalation kinetics. Through this strategy, an interlayer spacing of 13.99 angstrom between V-O layers is reached, offering large diffusion channels to accommodate NH4+ ions which have an ionic radius of 1.48 angstrom and a hydrated radius of 3.31 angstrom . The diffusion kinetics of the NH4+ ions, influenced by the hydrogen bonds formed between NH4+ ion and O2- in the host structure, are thus effectively enhanced by the unique pi-conjugated structure of PANI, leading to high capacity, improved rate capability and improved cycle life. The as-prepared PANI-intercalated V2O5 (PVO) demonstrates stable, ultrafast NH4+ ion electrochemical storage based on hydrogen bond chemistry as elucidated by X-ray photoelectron spectroscopy and Raman spectroscopy characterizations. Additionally, the composition of the PVO electrode is optimized with respect to the amount of PANI between the V-O layers. The PVO with an optimal composition exhibits the best overall electrochemical performance, delivering a high capacity of 192.5 mA hg(-1) and 39 mA hg(-1) at specific currents of 1 and 20 A g(-1) respectively, as well as a stable cycle life with a capacity retention of 98% at a specific current of 10 and 20 A g(-1). As such, the present work provides critical insights into the design of promising electrode materials for emerging aqueous non-metal batteries with intrinsic safety and reduced cost.

Renewable energy storage systems based on oxygen reduction reaction (ORR) call for high‐performance, durable, and low‐cost electrocatalysts. However, practical applications of ORR catalysts available today are hampered by the inability to load accessible catalytic sites efficiently. Herein, a novel and efficient ORR electrocatalyst (Fe2O3/FeNx@CNF) with atomic FeNx sites and neighboring Fe2O3 nanoparticles embedded in interconnected carbon nanofibers prepared via electrospinning is reported. Detailed material characterizations confirm that the as‐prepared catalysts possess a well‐defined fibrous structure with hierarchical pores, large specific surface area, and uniformly distributed Fe2O3/FeNx active sites. Further, it exhibits excellent ORR performance with high onset potential, half‐wave potential, and current density in both alkaline and acidic media. And these electrocatalysts show excellent long‐term performance and tolerance to methanol, exceeding the properties of commercial platinum catalysts. Additionally, the Fe2O3/FeNx@CNF electrocatalyst prepared in this study exhibits high discharge voltage, excellent power density, and cycling durability in Zn–air batteries. Notably, the detailed analyses demonstrate the co‐existence of Fe2O3 nanoparticles and FeNx active sites boost the ORR catalytic activity of the hybrid catalyst. These new findings, particularly the enhancement of intrinsic activity of FeNx sites brought about by Fe2O3 nanoparticles, provide insights into the rational design of hybrid single‐atom ORR electrocatalysts.

All solid materials are created via nucleation. In this evolutionary process, nuclei form in solution or at interfaces, expand by monomeric growth and oriented attachment, and undergo phase transformation. Nucleation determines the location and size of nuclei, whereas growth controls the size, shape, and aggregation of newly formed nanoparticles. These physical properties of nanoparticles can affect their functionalities, reactivities, and porosities, as well as their fate and transport. Recent advances in nanoscale analytical technologies allow in situ real-time observations, enabling us to uncover the molecular nature of nuclei and the critical controlling factors for nucleation and growth. Although a single theory cannot yet fully explain such evolving processes, we have started to better understand how both classical andnonclassical theories can work together, and we have begun to recognize the importance of connecting these theories. This review discusses the recent convergence of knowledge about the nucleation and growth of nanoparticles.

Batteries using a water-based electrolyte have the potential to be safer, more durable, less prone to thermal runaways, and less costly than current lithium batteries using an organic solvent. Among the possible aqueous battery options, ammonium-ion batteries (AIBs) are very appealing because the base materials are light, safe, inexpensive, and widely available. This review gives a concise and useful survey of recent progress on emerging AIBs, starting with a brief overview of AIBs, followed by cathode materials, anode materials, electrolytes, and various devices based on ammonium-ion storage. Aside from summarizing the most updated electrodes/electrolytes in AIBs, this review highlights fundamental mechanistic studies in AIBs and state-of-the art applications of ammonium-ion storage. The present work reviews various theoretical efforts and the spectrum studies that have been used to explore ionic transport kinetics, electrolyte structure, solvation behavior of ammonium ions, and the intercalation mechanism in the host structure. Furthermore, diverse applications of ammonium-ion storage apart from aqueous AIBs are discussed, including flexible AIBs, AIBs that can operate across a wide temperature range, ammonium-ion supercapacitors, and battery-supercapacitor hybrid devices. Finally, the review is concluded with perspectives of AIBs, challenges remaining in the field, and possible research directions to address these challenges to boost the performance of AIBs for real-world practical applications.

Non-metal ammonium (NH4+) ions have recently been explored as effective charge carriers in battery systems due to their abundancy, light weight, small hydration shells in water. The research concerning the use of NH4+ redox chemistry in batteries, particularly in flexible batteries, is still in its infancy. For the first time, we report a flexible full NH4+ ion battery (AIB) composed of a concentrated hydrogel electrolyte sandwiched between NH4V3O8 . 2.9H(2)O nanobelts cathode and polyaniline (PANI) anode, for enhanced performance. The hydrogel electrolyte is simply synthesized by using ammonium sulfate, xanthan gum and water. As a reference, the AIB based on the liquid aqueous electrolyte is prepared first, which exhibits a capacity of 121 mAh g(-1) and a capacity retention of 95 % after 400 cycles at a specific current of 0.1 A g(-1). On the other hand, the simple synthesis of the hydrogel electrolyte allows us to facilely tune and optimize the salt contents in the electrolyte, to maximize the ionic conductivity, transport kinetics, mechanical characteristics, and consequently the battery performance. It is found that the flexible battery based on the hydrogel electrolyte prepared from 3 M ammonium sulfate solution shows the best electrochemical performance, i. e., a capacity of 60 mAh g(-1) while maintaining a capacity retention of 88 % after 250 cycles at a specific current of 0.1 A g(-1). Moreover, the flexible AIB retains excellent electrochemical performance when bent at different angles, demonstrating remarkable mechanical strength and flexibility. Therefore, this study sheds new light on the utilization of concentrated hydrogel electrolyte in the AIB chemistry, for developments of novel electrochemical energy storage technology with high safety and low cost.

The emerging aqueous zinc-ion rechargeable batteries have attracted much attention, owing to their intrinsic safety and low cost. However, it is not practical to use zinc-ion batteries in frigid environments due to their liquid water-based electrolytes. To alleviate this issue, we have developed a flexible zinc-ion battery consisting of an optimized concentrated hydrogel electrolyte sandwiched between an ultrathin zinc anode and a NH4V3O8 center dot 1 center dot 9H(2)O cathode for enhanced performance at subzero temperature. The hydrogel electrolytes, synthesized by simply mixing xanthan gum and aqueous ZnCl2 solution, are examined via various characterizations, such as thermogravimetric analysis, tensile tests, adhesion tests, and impedance measurements, for understanding their fundamental properties. The contents of the xanthan gum and the zinc salt can be facilely tuned and optimized for maximized battery performance. It is found that when a concentrated hydrogel electrolyte is prepared using 1.2 g xanthan gum mixed in 4 m ZnCl2 solution, the resulted flexible battery delivers the best performance, exhibiting a very high capacity of 201 mAh g(-1) and 83 mAh g(-1) under 0.2 A g(-1) at -20 degrees C and -40 degrees C, respectively. The battery also exhibits re-markable cyclability over 1500 cycles at -20 degrees C. Additionally, the battery shows capacity retention of 92% capacity over 100 cycles while being bent by 90 degrees then 180 degrees at -20 degrees C. As such, this battery demonstrates excellent electrochemical performance and mechanical durability/flexibility as well as anti-freezing property, showing high potential to be used to power wearable electronics in cold environments or where safety is most crucial. (C) 2021 Elsevier Ltd. All rights reserved.

Salinity gradient (SG) energy is a large untapped energy source available worldwide. Here we applied MoS2 with tunable interlayer spacing to a concentration flow cell for efficient SG energy recovery. By expanding the interlayer from 0.63 nm to 0.96 nm, the ion diffusion resistance was significantly reduced and the pseudocapacitance was largely promoted. These enhanced electrochemical properties resulted in a superior performance of the concentration flow cell on SG energy extraction. The cell with interlayer-expanded MoS2 electrodes produced 11 times of the average power density compared with the cell with original MoS2 electrodes when using model seawater and river water solutions. The interlayer-expanded MoS2 was also among the most durable materials for SG energy harvesting as it allowed the cell to run over 120 cycles and work efficiently at varying salinity concentrations. When provided with brine water (300 g L-1 NaCl) and fresh water (1 g L-1 NaCl), the cell yielded a peak power density of 16 W m(-2), an average power density of 1.4 W m(-2), and an energy density of 181 J m(-2). All these evidences support that the interlayer-expanded MoS2 is a prospective material for SG energy recovery in concentration flow cells. (C) 2020 Elsevier Ltd. All rights reserved.

Rechargeable zinc-ion batteries (ZIBs) have shown great potential for grids-level energy storage system. However, the lack of desirable and stable cathode materials remains challenging. Herein, Sn1.5V2O7(OH)(2)center dot 3.3H(2)O, in which pyrovanadate V2O74- group pillared with Sn oxide layer, is developed as an advanced cathode for ZIBs and a hidden reaction mechanism in SnVO cathode through in-situ Raman and ex-situ XANEs, involves the opening of V-O edge bonding and formation of Sn-O-V bonding, which leads to charge screening effect and facilitates the fast diffusion kinetics for zinc ions, as quantitatively verified by kinetic analysis. Additionally, the tetravalent Sn ions bring about stronger ionic bonds, binding to pyrovanadate V2O74- group and leading to good stability in the pyrovanadate framework, which guarantee the cycling stability. As a result, the as-prepared SnVO shows long cycling life as well as excellent rate capability. We demonstrate that, even cycled at high current of 10 A/g, the SnVO cathode can still retain a capacity of 130 mAh/g for over 500 cycles, indicating remarkable high capacity at high rate. Our findings reveal that the tetravalent tin ions have a strong beneficial effect on the battery performance of the layered-structure cathode materials. It is believed that our study would boost further studies in other multi-valent rechargeable batteries.

A paradigm shift in aqueous rechargeable batteries has seen the development of nonmetal ammonium ions (NH4+) as charge carriers. NH4+ ions have a molecular weight of 18 g mol(-1) and hydrated ionic size of 3.31 A, which are smaller than those of metal ions, leading to faster kinetics during charge transfer. Yet few electrode materials have been studied for this type of battery. This work is the first effort to show that polyaniline (PANI) is an excellent material for NH4+ ion storage, and thus further proves that NH4+ ions can be used as effective charge carriers in aqueous ion battery systems. A facile solution method is used to prepare emeraldine salt polyaniline (ES-PANI) on the carbon felts (CFs) as the cathode material. The battery cell based on the ES-PANI cathode material shows a good discharge capacity of 160 mAh g(-1) at a specific current of 1 A g(-1). At 5 A g(-1), it shows a good capacity retention of 82% after 100 cycles and also exhibits excellent rate capability. Furthermore, it is found that the ES-PANI/CFs washed with water deliver higher capacity than those washed with ethanol, because washing with ethanol causes the oligomers to dissolve in the solution and thus decreases the storage capacity of ES-PANI for NH4+ ion storage. The intercalation/deintercalation of NH4+ ion is shown to be highly reversible in the ES-PANI electrode doped with Cl- ions, due to the stable redox properties of nitrogen in ES-PANI polymer chains. As such, this work sheds new insight into the exploration of alternative electrode material for ammonium ion storage, which can lead to new electrochemical energy technology.

High cost platinum (Pt) catalysts limit the application of microbial electrolysis cells (MECs) for hydrogen (H-2) production. Here, inexpensive and efficient Mo2N nanobelt cathodes were prepared using an ethanol method with minimized catalyst and binder loadings. The chronopotentiometry tests demonstrated that the Mo2N nanobelt cathodes had similar catalytic activities for H-2 evolution compared to that of Pt/C (10 wt%). The H-2 production rates (0.39 vs. 0.37 m(3)-H-2/m(3)/d), coulombic efficiencies (90% vs. 77%), and overall hydrogen recovery (74% vs. 70%) of MECs with the Mo2N nanobelt cathodes were also comparable to those with Pt/C cathodes. However, the cost of Mo2N nanobelt catalyst ($ 31/m(2)) was much less than that of Pt/C catalysts ($ 1930/m(2)). Furthermore, the biofilm microbiomes at electrodes were studied using the PacBio sequencing of fulllength 16S rRNA gene. It indicated Stenotrophomonas nitritireducens as a putative electroactive bacterium dominating the anode biofilm microbiomes. The majority of dominant species in the Mo2N and Pt/C cathode communities belonged to Stenotrophomonas nitritireducens, Stenotrophomonas maltophilia, and Comamonas testosterone. The dominant populations in the cathode biofilms were shaped by the cathode materials. This study demonstrated Mo2N nanobelt catalyst as an alternative to Pt catalyst for H-2 production in MECs.