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Abstract Electrochemical CO2 reduction reaction (CO2RR) to produce value‐added multi‐carbon chemicals has been an appealing approach to achieving environmentally friendly carbon neutrality in recent years. Despite extensive research focusing on the use of CO2 to produce high‐value chemicals like high‐energy‐density hydrocarbons, there have been few reports on the production of propane (C3H8), which requires carbon chain elongation and protonation. A rationally designed 0D/2D hybrid Cu2O anchored‐Ti3C2Tx MXene catalyst (Cu2O/MXene) is demonstrated with efficient CO2RR activity in an aqueous electrolyte to produce C3H8. As a result, a significantly high Faradaic efficiency (FE) of 3.3% is achieved for the synthesis of C3H8 via the CO2RR with Cu2O/MXene, which is ≈26 times higher than that of Cu/MXene prepared by the same hydrothermal process without NH4OH solution. Based on in‐situ attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR) and density functional theory (DFT) calculations, it is proposed that the significant electrocatalytic conversion originated from the synergistic behavior of the Cu2O nanoparticles, which bound the *C2 intermediates, and the MXene that bound the *CO coupling to the C3 intermediate. The results disclose that the rationally designed MXene‐based hybrid catalyst facilitates multi‐carbon coupling as well as protonation, thereby manipulating the CO2RR pathway.

Abstract Electrochemical nitrogen reduction reaction (NRR) is a sustainable alternative to the Haber‒Bosch process for ammonia (NH3) production. However, the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions. To overcome this challenge, we designed a vanadium oxide/nitride (V2O3/VN) hybrid electrocatalyst in which V2O3 and VN coexist coherently at the heterogeneous interface. Since single‐phase V2O3 and VN exhibit different surface catalytic kinetics for NRR, the V2O3/VN hybrid electrocatalyst can provide alternating reaction pathways, selecting a lower energy pathway for each material in the serial NRR pathway. As a result, the ammonia yield of the V2O3/VN hybrid electrocatalyst was 219.6 µg h−1 cm−2, and the Faradaic efficiency was 18.9%, which is much higher than that of single‐phase VN, V2O3, and VNxOy solid solution catalysts without heterointerfaces. Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low‐energy reaction pathway through the migration and adsorption of intermediate species. Therefore, the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient electrochemical catalysts that induce steps favorable for the efficient low‐energy progression of NRR.

Abstract The development of a cost‐competitive and efficient electrocatalyst is both attractive and challenging for hydrogen production by hydrogen evolution reaction (HER). Herein, a facile glycol reduction method to construct Ru nanoclusters coupled with hierarchical exfoliated‐MXene/reduced graphene oxide architectures (Ru‐E‐MXene/rGA) is reported. The hierarchical structure, formed by the self‐assembly of graphene oxides, can effectively prohibit the self‐stacking of MXene nanosheets. Meanwhile, the formation of the MXene/rGA interface can strongly trap the Ru3+ ions, resulting in the uniform distribution of Ru nanoclusters within Ru‐E‐MXene/rGA. The boosted catalytic activity and underlying catalytic mechanism during the HER process are proved by density functional theory. Ru‐E‐MXene/rGA exhibits overpotentials of 42 and 62 mV at 10 mA cm−2 in alkaline and acidic electrolytes, respectively. The small Tafel slope and charge transfer resistance (Rct) values elucidate its fast dynamic behavior. The cyclic voltammetry (CV) curves and chronoamperometry test confirm the high stability of Ru‐E‐MXene/rGA. These results demonstrate that coupling Ru nanoclusters with the MXene/rGA heterostructure represents an efficient strategy for constructing MXene‐based catalysts with enhanced HER activity.

Technology advancements in energy storage, photocatalysis, and sensors have generated enormous impedimetric data. Electrochemical impedance spectroscopy (EIS) results play an essential role in analyzing the interfacial properties of materials. Nonetheless, in many situations, the data is misinterpreted due to the complexity of the electrochemical system or the compromise between the experimental result and the theoretical model, resulting in partiality in the interpretation process, especially for the impedimetric results. Typically, the experimenter interprets impedimetric results using a searching approach based on a theoretical model until the best‐fitting model is obtained, which is a time‐consuming process, and errors can occur. To reduce misinterpretation by the experimenter, herein, the machine‐learning strategy is demonstrated for the classification of an EIS circuit model and parameter prediction using a deep neural network (DNN). The DNN model shows a highly accurate classifier for the commonly used EIS circuit with an average area under the receiver operating characteristic curve of more than 0.95. Additionally, the model demonstrates high accuracy in the prediction of EIS parameters on a complex EIS system, with a maximum R2 of 0.999. These reveal that the machine‐learning strategy may open a new room for studying electrochemical systems.

Abstract A rational regulation of the solar water splitting reaction pathway by adjusting the surface composition and phase structure of catalysts is a substantial approach to ameliorate the sluggish reaction kinetics and improve the energy conversion efficiency. In this study, we demonstrate a nanocrystalline iron pyrophosphate (Fe4(P2O7)3, FePy)-regulated hybrid overlayer with amorphous iron phosphate (FePO4, FePi) on the surface of metal oxide nanostructure with boosted photoelectrochemical (PEC) water oxidation. By manipulating the facile electrochemical surface treatment followed by the phosphating process, nanocrystalline FePy is localized in the FePi amorphous overlayer to form a heterogeneous hybrid structure. The FePy-regulated hybrid overlayer (FePy@FePi) results in significantly enhanced PEC performance with long-term durability. Compared with the homogeneous FePi amorphous overlayer, FePy@FePi can improve the charge transfer efficiency more significantly, from 60% of FePi to 79% of FePy@FePi. Our density-functional theory calculations reveal that the coexistence of FePi and FePy phases on the surface of metal oxide results in much better oxygen evolution reaction kinetics, where the FePi was found to have a typical down-hill reaction for the conversion from OH* to O2, while FePy has a low free energy for the formation of OH*. Graphical abstract

Abstract All‐solid‐state battery (ASSB) technology is the focus of considerable interest owing to their safety and the fact that their high energy density meets the requirements of emerging battery applications, such as electric vehicles and energy storage systems (ESSs). In light of this, current research on high‐energy ASSBs harnesses the benefits of solid‐state battery systems by employing anode materials with high energy densities. Owing to the excellent physical safety of solid electrolytes, it is possible to build a battery with high energy density by using high‐energy negative electrode materials and decreasing the amount of electrolyte in the battery system. Sulfide‐based ASSBs with high ionic conductivity and low physical contact resistance is recently receiving considerable attention. This review provides a summary on various anode materials for ASSBs operating under electrochemically reducing conditions from the perspective of electrochemical and physical safety. The electrochemical and physical properties of sulfide electrolytes used for lithium (Li) metal and particle‐type anode materials are presented, as well as strategies for mitigating interfacial failures in solid‐state cells through interlayer and electrode design.

Abstract A versatile use of a sulfur self‐doped biochar derived from Camellia japonica (camellia) flowers is demonstrated as a multifunctional catalyst for overall water splitting and a supercapacitor. The native sulfur content in the camellia flower facilitates in situ self‐doping of sulfur, which highly activates the camellia‐driven biochar (SA‐Came) as a multifunctional catalyst with the enhanced electron‐transfer ability and long‐term durability. For water splitting, an SA‐Came‐based electrode is highly stable and shows reaction activities in both hydrogen and oxygen evolution reactions, with overpotentials of 154 and 362 mV at 10 mA cm−2, respectively. For supercapacitors, SA‐Came achieves a specific capacitance of 125.42 F g−1 at 2 A g−1 and high cyclic stability in a three‐electrode system in a 1 M KOH electrolyte. It demonstrated a high energy density of 34.54 Wh kg−1 at a power density of 1600 W kg−1 as a symmetric hybrid supercapacitor device with a wide working potential range of 0–1.6 V.

Background: Withania somnifera (Solanaceae), generally known as Indian ginseng, is a medicinal plant that is used in Ayurvedic practice for promoting health and longevity. This study aims to identify the bioactive metabolites from Indian ginseng and elucidate their structures. Methods: Withanolides were purified by chromatographic techniques, including HPLC coupled with LC/MS. Chemical structures of isolated withanolides were clarified by analyzing the spectroscopic data from 1D and 2D NMR, and HR-ESIMS experiment. Absolute configurations of the withanolides were established by the application of NMR chemical shifts and ECD calculations. Anti-adipogenic activities of isolates were evaluated using 3T3-L1 preadipocytes with Oil Red O staining and quantitative real-time PCR (qPCR). Results: Phytochemical examination of the roots of Indian ginseng afforded to the isolation of six withanolides (1–6), including three novel withanolides, withasilolides G–I (1–3). All the six compounds inhibited adipogenesis and suppressed the enlargement of lipid droplets, compared to those of the control. Additionally, the mRNA expression levels of Fabp4 and Adipsin, the adipocyte markers decreased noticeably following treatment with 25 μM of 1–6. The active compounds (1–6) also promoted lipid metabolism by upregulating the expression of the lipolytic genes HSL and ATGL and downregulating the expression of the lipogenic gene SREBP1. Conclusion: The results of our experimental studies suggest that the withasilolides identified herein have anti-adipogenic potential and can be considered for the development of therapeutic strategies against adipogenesis in obesity. Our study also provides a mechanistic rationale for using Indian ginseng as a potential therapeutic agent against obesity and related metabolic diseases.

Hydrogen has become an indispensable aspect of sustainable energy resources due to depleting fossil fuels and increasing pollution. Since hydrogen storage and transport is a major hindrance to expanding its applicability, green ammonia produced by electrochemical method is sourced as an efficient hydrogen carrier. Several heterostructured electrocatalysts are designed to achieve significantly higher electrocatalytic nitrogen reduction (NRR) activity for electrochemical ammonia production. In this study, we controlled the nitrogen reduction performances of Mo2C-Mo2N heterostructure electrocatalyst prepared by a simple one pot synthesis method. The prepared Mo2C-Mo2N0.92 heterostructure nanocomposites show clear phase formation for Mo2C and Mo2N0.92, respectively. The prepared Mo2C-Mo2N0.92 electrocatalysts deliver a maximum ammonia yield of about 9.6 μg h-1 cm-2 and a Faradaic efficiency (FE) of about 10.15%. The study reveals the improved nitrogen reduction performances of Mo2C-Mo2N0.92 electrocatalysts due to the combined activity of the Mo2C and Mo2N0.92 phases. In addition, the ammonia production from Mo2C-Mo2N0.92 electrocatalysts is intended by the associative nitrogen reduction mechanism on Mo2C phase and by Mars-van-Krevelen mechanism on Mo2N0.92 phase, respectively. This study suggests the importance of precisely tuning the electrocatalyst by heterostructure strategy to substantially achieve higher nitrogen reduction electrocatalytic activity.

Breast cancer ranks among the most prevalent malignancies affecting women worldwide, and apoptosis-targeting drugs are attractive candidates for the treatment of cancer. In the current study, we investigated the in vitro cytotoxicity of the mushroom Calvatia nipponica in human breast cancer cells (MDA-MB-231), identified potential antitumor compounds through bioactivity-guided isolation, and elucidated the antitumor, pro-apoptotic molecular mechanisms of the identified bioactive compounds. C. nipponica is edible when young, and it has been used as a food source as well as a traditional medicine in wound dressings. However, only a limited number of studies have reported its chemical composition and biological activities. In the screening test, the methanol extract of C. nipponica fruiting bodies exhibited cytotoxicity against MDA-MB-231 cells. Bioactivity-guided fractionation of the methanol (MeOH) extract and chemical investigation of the active fractions resulted in the isolation of fourteen compounds (1–14), including six alkaloids (1–3, 5, 7, and 8), two phenolic compounds (4 and 6), one fatty acid (9), and five steroids (10–14). The structures of the isolated compounds were determined using NMR spectroscopic methods, liquid chromatography–mass spectrometry, and comparison of data with previously reported values. The isolated compounds (1–14) were tested for cytotoxicity against MDA-MB-231 cells, where compound 1, i.e., N,N-dimethyl-anthranilic acid, exhibited the most significant cytotoxicity against MDA-MB-231 cells, with an IC50 value of 90.28 ± 4.23 μM and apoptotic cell death of 56.01% ± 2.64% at 100 μM. Treatment with compound 1 resulted in an upregulation of protein levels, including cleaved caspase-8, cleaved poly (ADP-ribose) polymerase, Bcl-2-associated X protein (Bax), cleaved caspase-3, cleaved caspase-9, Bad, and Cytochrome c, but decreased the levels of B-cell lymphoma 2 (Bcl-2). Overall, these results indicate that N,N-dimethyl-anthranilic acid (1) may have anti-breast cancer activity and is probably involved in the induction of apoptosis mediated by extrinsic and intrinsic signaling pathways.

In this study, high-crystallinity single walled carbon nanotubes (H-SWNTs) were prepared by high-temperature thermal annealing at 1800 °C and a self-heating shape memory polyurethane nanocomposite with excellent self-heating characteristics was developed within a few seconds by irradiation with near-infrared rays. With a simple method (heat treatment), impurities at the surface of H-SWNTs were removed and at the same time the amorphous structure converted into a crystalline structure, improving crystallinity. Therefore, high conductivity (electric, thermal) and interfacial affinity with PU were increased, resulting in improved mechanical, thermal and electric properties. The electrical conductivity of neat polyurethane was enhanced from ~10–11 S/cm to 4.72 × 10−8 S/cm, 1.07 × 10−6 and 4.66 × 10−6 S/cm, while the thermal conductivity was enhanced up to 60% from 0.21 W/mK, 0.265 W/mK and 0.338 W/mK for the composites of 1, 3 and 5 wt%, respectively. Further, to achieve an effective photothermal effect, H-SWNTs were selected as nanofillers to reduce energy loss while increasing light-absorption efficiency. Thereafter, near-infrared rays of 818 nm were directly irradiated onto the nanocomposite film to induce photothermal properties arising from the local surface plasmon resonance effect on the CNT surface. A self-heating shape memory composite material that rapidly heated to 270 °C within 1 min was developed, even when only 3 wt.% of H-SWNTs were added. The results of this study can be used to guide the development of heat-generating coating materials and de-icing materials for the wing and body structures of automobiles or airplanes, depending on the molding method.

Hepatocellular carcinoma (HCC) is the fastest-growing tumor capable of spreading to other organs via blood vessels formed by endothelial cells. Apoptosis and angiogenesis-targeting therapies are attractive for cancer treatment. In this study, we aimed to study the in vitro cytotoxicity of Withania somnifera against human HCC (HepG2) cells, identify potential antitumoral withanolide glycosides from the active fraction, and elucidate cytotoxic molecular mechanisms of identified bioactive compounds. W. somnifera (Solanaceae), well-known as ‘ashwagandha’, is an Ayurvedic medicinal plant used to promote health and longevity, and the MeOH extract of W. somnifera root exhibited cytotoxicity against HepG2 cells during initial screening. Bioactivity-guided fractionation of the MeOH extract and subsequent phytochemical investigation of the active n-BuOH-soluble fraction resulted in the isolation of five withanolide glycosides (1–5), including one new metabolite, withanoside XIII (1), aided by liquid chromatography–mass spectrometry-based analysis. The new compound structure was determined by 1D and 2D nuclear magnetic resonance spectroscopy, high-resolution electrospray ionization mass spectroscopy, electronic circular dichroism, and enzymatic hydrolysis. In addition, withanoside XIIIa (1a) was identified as the new aglycone (1a) of 1. Isolated withanolide glycosides 1–5 and 1a were cytotoxic toward HepG2 cells; withagenin A diglucoside (WAD) (3) exhibited the most potent cytotoxicity against HepG2 cells, with cell viability less than 50% at 100 μM. WAD cytotoxicity was mediated by both extrinsic and intrinsic apoptosis pathways. Treatment with WAD increased protein expression levels of cleaved caspase-8, cleaved caspase-9, cleaved caspase-3, Bcl-2-associated X protein (Bax), and cleaved poly(ADP-ribose) polymerase (cleaved PARP) but decreased expression levels of B-cell lymphoma 2 (Bcl-2). Moreover, WAD inhibited tubular structure formation in human umbilical vein endothelial cells (HUVECs) by inhibiting the protein expression of vascular endothelial growth factor receptor 2 and its downstream pathways, including extracellular signal-regulated kinase (ERK), phosphoinositide 3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR). These effects were also enhanced by co-treatment with ERK and PI3K inhibitors. Overall, these results indicate that WAD (3) induced HepG2 apoptosis and inhibited HUVEC tube formation, suggesting its potential application in treating liver cancers.

Withania somnifera (Solanaceae), commonly known as “ashwagandha”, is an ayurvedic medicinal plant that has been used for promoting good health and longevity. As part of our ongoing natural product research for the discovery of bioactive phytochemicals with novel structures, we conducted a phytochemical analysis of W. somnifera root, commonly used as an herbal medicine part. The phytochemical investigation aided by liquid chromatography-mass spectrometry (LC/MS)-based analysis led to the isolation of four withanolide glycosides (1–4), including one new compound, withanoside XII (1), from the methanol (MeOH) extract of W. somnifera root. The structure of the new compound was determined by nuclear magnetic resonance (NMR) spectroscopic data, high-resolution (HR) electrospray ionization (ESI) mass spectroscopy (MS), and electronic circular dichroism (ECD) data as well as enzymatic hydrolysis followed by LC/MS analysis. In addition, enzymatic hydrolysis of 1 afforded an aglycone (1a) of 1, which was identified as a new compound, withanoside XIIa (1a), by the interpretation of NMR spectroscopic data, HR-ESIMS, and ECD data. To the best of our knowledge, the structure of compound 2 (withagenin A diglucoside) was previously proposed by HRMS and MS/MS spectral data, without NMR experiment, and the physical and spectroscopic data of withagenin A diglucoside (2) are reported in this study for the first time. All the isolated compounds were evaluated for their anti-Helicobacter pylori, anti-oxidant, and anti-inflammatory activities. In the anti-Helicobacter pylori activity assay, compound 2 showed weak anti-H. pylori activity with 7.8% inhibition. All the isolated compounds showed significant ABTS radical scavenging activity. However, all isolates failed to show inhibitory activity against nitric oxide (NO) production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. This study demonstrated the experimental support that the W. somnifera root is rich in withanolides, and it can be a valuable natural resource for bioactive withanolides.

Background and objective The purpose of this study is to analyze the effects of short-term off-season training (competition) on body composition, physical fitness, and isokinetic muscle functions of XC skiers. Materials and Methods Seven XC skiers, including two national team members and five reserve national team members, participated in the study. Short-term off-season XC ski training was conducted for over 4 weeks (August– September). The physical composition, basic physical fitness, and isokinetic muscle function tests were conducted at S hospital in Seoul, South Korea before and after off-season ski training. The training program was conducted in New Zealand at S cross-country ski stadium (altitude 1350 m) in afternoons, and the ground training was conducted at Y area (altitude 300 m) in afternoons. The main training directions were polarized training and core stability. Weight training was not available because of local conditions. Results The short-term off-season XC ski training showed no differences (p>0.05) in body composition, such as weight, muscle mass, and body fat. There were significant differences (p0.05) in the antebrachial, femoral, and crural muscles. Basic physical fitness tests showed no significant differences (p>0.05) in strength, flexibility, agility, and balance. However, the power ratio between the right and left grip strength showed significant difference (p0.05) in both knee extensions before and after training, but, in contrast, there were significant differences (right knee, p0.05) between before and after training measurements. Conclusion Short-term off-season XC ski training (competition) of 4 weeks increased XC skiers’ cross-section area of the chest and brachial muscle. It also improved the isokinetic muscle function of knee joints and the power of lower body. Our research is expected to provide basic information for XC skiers who plan ski training and competition during summer training period. However, further studies on the differences between roller-skating and ski training conducted during summers are needed.

The aim of this study was to explore the protective effects of bioactive compounds from the fruit of the mulberry tree (Morus alba L.) against cisplatin-induced apoptosis in LLC-PK1 pig kidney epithelial cells. Morus alba fruit is a well-known edible fruit commonly used in traditional folk medicine. Chemical investigation of M. alba fruit resulted in the isolation and identification of six phytosterols (1–6). Their structures were determined as 7-ketositosterol (1), stigmast-4-en-3β-ol-6-one (2), (3β,6α)-stigmast-4-ene-3,6-diol (3), stigmast-4-ene-3β,6β-diol (4), 7β-hydroxysitosterol 3-O-β-d-glucoside (5), and 7α-hydroxysitosterol 3-O-β-d-glucoside (6) by analyzing their physical and spectroscopic data as well as liquid chromatography/mass spectrometry data. All compounds displayed protective effects against cisplatin-induced LLC-PK1 cell damage, improving cisplatin-induced cytotoxicity to more than 80% of the control value. Compound 1 displayed the best effect at a relatively low concentration by inhibiting the percentage of apoptotic cells following cisplatin treatment. Its molecular mechanisms were identified using Western blot assays. Treatment of LLC-PK1 cells with compound 1 decreased the upregulated phosphorylation of p38 and c-Jun N-terminal kinase (JNK) following cisplatin treatment. In addition, compound 1 significantly suppressed cleaved caspase-3 in cisplatin-induced LLC-PK1 cells. Taken together, these findings indicated that cisplatin-induced apoptosis was significantly inhibited by compound 1 in LLC-PK1 cells, thereby supporting the potential of 7-ketositosterol (1) as an adjuvant candidate for treating cisplatin-induced nephrotoxicity.

Phaseolus multiflorus var. albus (Leguminosae), commonly known as “white kidney bean”, is a twining perennial vine whose fruit has been used as a popular food worldwide owing to its high nutritional content, in terms of proteins, carbohydrates, fats, and vitamins. As part of our ongoing study to investigate novel bioactive components from various natural resources, a phytochemical investigation of the extract of P. multiflorus var. albus fruits resulted in the isolation of three phenolic compounds (1–3) and one dipeptide (4). The chemical structures of the compounds (1–4) were determined through 1D and 2D nuclear magnetic resonance spectroscopy and high-resolution-liquid chromatography–mass spectrometry; they were identified as denatonium (1), trans-ferulic acid ethyl ester (2), eugenin (3), and α-L-glutamyl-L-Leucine (4). Intriguingly, denatonium (1) is known to be the most bitter chemical compound. To the best of our knowledge, denatonium (1) was identified from natural sources for the first time, and compounds 2–4 were reported for the first time from P. multiflorus var. albus in this study; however, compound 2 turned out to be an artifact produced by an extraction with ethanol. The isolated compounds 1–4 were tested for their regulatory effects on the differentiation between osteogenesis and adipogenesis of mesenchymal stem cells (MSCs). Compound 4 slightly suppressed the adipogenic differentiation of MSCs, and compounds 1 and 4 stimulated osteogenic differentiation, unlike the negative control. These findings provide experimental evidence that compounds 1 and 4 may induce the osteogenesis of MSCs and activate bone formation.

Hippophae rhamnoides L. (Elaeagnaceae), commonly known as “Sea buckthorn” and “Vitamin tree”, is a spiny deciduous shrub whose fruit is known for its nutritional composition, such as vitamin C, and is consumed as a dietary supplement worldwide. As part of our ongoing efforts to identify structurally new and bioactive constituents from natural resources, the phytochemical investigation of the extract of H. rhamnoides fruits led to the isolation of one malate derivative (1), five citrate derivatives (2–6), and one quinate derivative (7). The structures of the isolated compounds were elucidated by analysis of 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data and high-resolution electrospray ionization (HR-ESI) liquid chromatography–mass spectrometry (LC/MS) data. Three of the citrate derivatives were identified as new compounds: (S)-1-butyl-5-methyl citrate (3), (S)-1-butyl-1′-methyl citrate (4), and (S)-1-methyl-1′-butyl citrate (6), which turned out to be isolation artifacts. The absolute configurations of the new compounds were established by quantum chemical electronic circular dichroism (ECD) calculation, which is an informative tool for verifying the absolute configuration of organic acid derivatives. The isolated compounds 1–7 were evaluated for their stimulatory effects on osteogenesis. Compounds 1, 3, 4, 6, and 7 stimulated osteogenic differentiation up to 1.4 fold, compared to the negative control. These findings provide experimental evidence that active compounds 1, 3, 4, 6, and 7 induce the osteogenesis of mesenchymal stem cells and activate bone formation.

Inhibition of the megakaryocyte protein tyrosine phosphatase 2 (PTP-MEG2, also named PTPN9) activity has been shown to be a potential therapeutic strategy for the treatment of type 2 diabetes. Previously, we reported that PTP-MEG2 knockdown enhances adenosine monophosphate activated protein kinase (AMPK) phosphorylation, suggesting that PTP-MEG2 may be a potential antidiabetic target. In this study, we found that phloridzin, isolated from Ulmus davidiana var. japonica, inhibits the catalytic activity of PTP-MEG2 (half-inhibitory concentration, IC50 = 32 ± 1.06 μM) in vitro, indicating that it could be a potential antidiabetic drug candidate. Importantly, phloridzin stimulated glucose uptake by differentiated 3T3-L1 adipocytes and C2C12 muscle cells compared to that by the control cells. Moreover, phloridzin led to the enhanced phosphorylation of AMPK and Akt relevant to increased insulin sensitivity. Importantly, phloridzin attenuated palmitate-induced insulin resistance in C2C12 muscle cells. We also found that phloridzin did not accelerate adipocyte differentiation, suggesting that phloridzin improves insulin sensitivity without significant lipid accumulation. Taken together, our results demonstrate that phloridzin, an inhibitor of PTP-MEG2, stimulates glucose uptake through the activation of both AMPK and Akt signaling pathways. These results strongly suggest that phloridzin could be used as a potential therapeutic candidate for the treatment of type 2 diabetes.

In this study, a solution-processable compact vanadium oxide (V2O5) film with a globular nanoparticulate structure is introduced to the hole transport layer (HTL) of polymer bulk-heterojunction based solar cells comprised of PTB7:PC70BM by using a facile metal-organic decomposition method to replace the conventionally utilized poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). For this, a biocompatible structure-determining agent, polyethylene glycol (PEG, Mn 300), is used as an additive in the precursor to form the nanoparticulate compact V2O5 (hereafter referred to as NP-V2O5) film, which possesses an outstandingly smooth surface morphology. The introduction of NP-V2O5 HTL via the solution process with a neutral pH condition successfully improved the stability by preventing the decomposition of indium tin oxide (ITO) glass and the penetration of heavy-metal components and moisture, which are considered as the crucial drawbacks of using PEDOT:PSS. Over 1440 h (60 days) of the stability test, an organic solar cell (OSC) with NP-V2O5 showed a significant durability, maintaining 82% of its initial power conversion efficiency (PCE), whereas an OSC with PEDOT:PSS maintained 51% of its initial PCE. Furthermore, due to the positive effects of the modified surface properties of NP-V2O5, the PCE was slightly enhanced from 7.47% to 7.89% with a significant improvement in the short-circuit current density and fill factor.

The unique physical and chemical properties of spinels have made them highly suitable electrocatalysts in oxygen evolution reaction and oxygen reduction reaction (OER & ORR). Zinc–air batteries (ZABs), which are safer and more cost-effective power sources than commercial lithium-ion batteries, hinge on ORR and OER. The slow kinetics of the air electrode reduce its high theoretical energy density and specific capacity, which limits its practical applications. Thus, tuning the performance of the electrocatalyst and cathode architecture is vital for improving the performance of ZABs, which calls for exploring spinel, a material that delivers improved performance. However, the structure–activity relationship of spinel is still unclear because there is a lack of extensive information about it. This study was performed to address the promising potential of spinel as the bifunctional electrocatalyst in ZABs based on an in-depth understanding of spinel structure and active sites at the atomic level.

Sustainability is highly desired for human beings due to a rapidly changing global climate and numerous environmental issues. In past decades, state-of-the-art studies have been extensively conducted to achieve sustainable energy conversion and storage. However, the remaining challenges in the commercialization of energy conversion and storage devices are to develop novel materials and advanced manufacturing processes. Furthermore, the engineering of nanostructures and device-architectures is of great importance for the energy conversion and storage flat forms. This Special Issue “Novel Materials for Sustainable Energy Conversion and Storage” aims the state-of-the-art research reports of novel nanomaterials and the engineering of device architectures for divergent energy conversion and storage applications with high sustainability involving solar energy systems, electrochemical cells, artificial photosynthesis or secondary (rechargeable) batteries, as highlighted in this editorial.

Hydrogen-evolution reaction (HER) is a promising technology for renewable energy conversion and storage. Electrochemical HER can provide a cost-effective method for the clean production of hydrogen. In this study, a biomimetic eco-friendly approach to fabricate nitrogen-doped carbon nanosheets, exhibiting a high HER performance, and using a carbonized polydopamine (C-PDA), is described. As a biopolymer, polydopamine (PDA) exhibits high biocompatibility and can be easily obtained by an environmentally benign green synthesis with dopamine. Inspired by the polymerization of dopamine, we have devised the facile synthesis of nitrogen-doped nanocarbons using a carbonized polydopamine for the HER in acidic media. The N-doped nanocarbons exhibit excellent performance for H2 generation. The required overpotential at 5 mA/cm2 is 130 mV, and the Tafel slope is 45 mV/decade. Experimental characterizations confirm that the excellent performance of the N-doped nanocarbons can be attributed to the multisite nitrogen doping, while theoretical computations indicate the promotion effect of tertiary/aromatic nitrogen doping in enhancing the spin density of the doped samples and consequently in forming highly electroactive sites for HER applications.

In this study, simple electrospinning combined with pyrolysis were used to fabricate transition-metal-based-nanoparticle-incorporated carbon nanofiber (CNF) electrocatalysts for a high-efficiency hydrogen evolution reaction (HER) and overall water splitting. Co-CeO2 nanoparticle-incorporated carbon nanofibers (Co-CeO2@CNF) exhibit an outstanding electrocatalytic HER performance with an overpotential and Tafel slope of 92 mV and 54 mV/dec, respectively. For the counterpart, electrolysis, we incorporate the widely used Ni2Fe catalyst with a high oxygen evolution reaction (OER) activity into the carbon nanofiber (Ni2Fe@CNF). To evaluate their electrochemical properties for the overall water splitting, Co-CeO2@CNF and Ni2Fe@CNF were used as the HER and OER electrocatalysts in an alkaline electrolyzer. With the paired Co-CeO2@CNF and Ni2Fe@CNF electrodes, an overall water splitting current density of 10 mA/cm2 was achieved by applying 1.587 V across the electrodes with a remarkably lower overpotential of 257 mV compared to that of an electrolyzer comprised of Pt/C and IrO2 electrodes (400 mV). Owing to the conformal incorporation of nanoparticles into the CNF, the electrocatalysts exhibit significant long-term durability over 70 h of overall water splitting. This study provides rational designs of catalysts with high electrochemical catalytic activity and durability to achieve overall water splitting.

Poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) is typically used for hole transport layers (HTLs), as it exhibits attractive mechanical, electrical properties, and easy processability. However, the intrinsically acidic property can degrade the crystallinity of perovskites, limiting the stability and efficiency of perovskite solar cells (PSCs). In this study, inverted CH3NH3PbI3 photovoltaic cells were fabricated with acidity suppressed HTL. We adjusted PEDOT:PSS via a solution reaction of acidic and neutral PEDOT:PSS. And we compared the various pH-controlled HTLs for PSCs devices. The smoothness of the pH-controlled PEDOT:PSS layer was similar to that of acidic PEDOT:PSS-based devices. These layers induced favorable crystallinity of perovskite compared with acidic PEDOT:PSS layers. Furthermore, the enhanced stability of pH optimized PEDOT:PSS-based devices, including the prevention of degradation by a strong acid, allowed the device to retain its power conversion efficiency (PCE) value by maintaining 80% of PCE for approximately 150 h. As a result, the pH-controlled HTL layer fabricated through the solution reaction maintained the surface morphology of the perovskite layer and contributed to the stable operation of PSCs.

As a p-type metal oxide, nickel oxide (NiO) has been extensively utilized for providing a favorable hole transport pathway in organic solar cells (OSCs). To obtain higher crystallinity, a post-annealing process at high temperature is required for the NiO layer. Therefore, fluorine-doped tin oxide (FTO) glass has been widely used for the substrate of NiO. However, the rough surface of the FTO substrate deteriorates the interfacial properties of the NiO layer, which hinders efficient charge extraction in OSCs. In this study, a facile polyethylene glycol (PEG)-assisted sol-gel synthesis of the compact NiO layer as the hole-selective layer is demonstrated. The compact NiO layer has a significantly uniform and smooth surface morphology, facilitating better interfacial properties for favorable charge transport. The modified interfacial properties outstandingly promote the charge migration and recombination blocking in OSCs. In addition, a hybrid structure with compact NiO and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is designed to form a cascade charge extraction and passivate possible pinholes on the NiO layer. Consequently, the compact NiO layer enhances all the parameters determining the power conversion efficiency, including the open-circuit potential (Voc), short-circuit current density (Jsc), and fill factor (FF).

A conformal titanyl phosphate passivation with the thickness of ca. 5 nm on the surface of TiO2 nanoparticles for enhancing the photocatalytic degradation of organic pollutants and hydrogen production is described. The phosphate anion species bound to the surface of TiO2 promote the favorable kinetics of photocatalytic activity and influence the catalytic reaction pathway. By using a facile surfactant-assisted sol-gel process, the surface defects of TiO2 associated with deep traps was reduced and passivated by the phosphate anion species to form the titanyl phosphate. The strong bonds between the titanyl phosphate shell and TiO2 core provided a long-term photochemical stability in aqueous electrolytes with enhanced photocatalytic activities. The titanyl phosphate contributed to the production and stabilization of hydroxyl radicals on the surface of photocatalyst, which facilitated the efficient photooxidation of the organic pollutants. Further, enhancing the photocatalytic hydrogen production was achieved by the titanyl phosphate modified TiO2 (TP-TiO2). Consequently, the conformal titanyl phosphate passivation enhanced photocatalytic activity of TiO2. Comparing to the bare TiO2 nanoparticles, approximately two-fold higher photocatalytic H2 production rate was achieved by the TP-TiO2.

Traditional challenges of poor cycling stability and low Coulombic efficiency in Zinc (Zn) metal anodes have limited their practical application. To overcome these issues, this work introduces a single metal-atom design featuring atomically dispersed single copper (Cu) atoms on 3D nitrogen (N) and oxygen (O) co-doped porous carbon (CuNOC) as a highly reversible Zn host. The CuNOC structure provides highly active sites for initial Zn nucleation and further promotes uniform Zn deposition. The 3D porous architecture further mitigates the volume changes during the cycle with homogeneous Zn2+ flux. Consequently, CuNOC demonstrates exceptional reversibility in Zn plating/stripping processes over 1000 cycles at 2 and 5 mA cm-2 with a fixed capacity of 1 mAh cm-2, while achieving stable operation and low voltage hysteresis over 700 h at 5 mA cm-2 and 5 mAh cm-2. Furthermore, density functional theory calculations show that co-doping N and O on porous carbon with atomically dispersed single Cu atoms creates an efficient zincophilic site for stable Zn nucleation. A full cell with the CuNOC host anode and high loading V2O5 cathode exhibits outstanding rate-capability up to 5 A g-1 and a stable cycle life over 400 cycles at 0.5 A g-1. [ABSTRACT FROM AUTHOR]